Caffeine is one of the most popular ergogenic aids in the world, but it has the potential to impact sleep quality and recovery time, resulting in lower physical and cognitive function. So how do athletes strike the best balance?

By Dr. James Morehen
Last updated: March 23rd, 2023
6 min read

Original study

Caia, J., Halson, S. L., Holmberg, P. M., & Kelly, V. G. (2021). Does Caffeine Consumption Influence Postcompetition Sleep in Professional Rugby League Athletes? A Case Study. International Journal of Sports Physiology and Performance, 17(1), 126-129.

Click here for abstract

Background & Objective

Caffeine is one of the most popular ergogenic aids in the world. Worldwide consumption is crazy, with many everyday people consuming it daily and athletes using it as a stimulant before training and competition (infographic below). Personally, I have seen athletes consume multiple cans of energy drinks each day without any understanding as to how much caffeine they have consumed.

Caffeine consumption can affect numerous sleep indices, such as sleep onset latency and efficiency, rapid eye movement sleep, total sleep time, insomnia, anxiousness, and activity in athletes. As a result, caffeine has the potential to reduce sleep quality and recovery time, resulting in lower physical and cognitive function, especially when caffeine has been consumed in the evening.
The aim of this study was to (1) explore sleep in rugby league athletes before and after an evening match, and (2) investigate the relationship between changes in salivary caffeine concentration and sleep on the night of competition.

What They Did

Fifteen professional rugby league athletes were recruited – all players were regular caffeine consumers prior to taking part in study.

Prior to and during an evening (7:50 pm kick off) rugby league match, players consumed ad libitum (as much or as often or desired) a commercially-available pre-workout supplement, and/or tablets which contained approximately 175mg and 100mg of caffeine per serving respectively.

Saliva samples were collected from the players using a synthetic swab for 45 seconds, one-hour before and 30 minutes after the game, and then frozen ready for later analysis. High-performance liquid chromatography was used to examine saliva samples for caffeine.

Sleep was evaluated on three occasions: the night before the match, the night of the match, and the night following the match using an activity monitor (Actiwatch 2) worn on the players’ wrists, as well as a self-report sleep diary. This allowed both an objective estimation of sleep and also a subjective self-report of player sleep time.

What They Found

One hour prior to competition, the salivary caffeine concentration of players was 2.1 μg/mL. Compared with pre-competition measures, post-competition salivary caffeine concentration was significantly increased (8.1 μg/mL)
Evening competition caused significant adjustments in sleep-wake cycles, as well as shorter sleep duration: on the night of the match, players slept an average 4 hours 27 minutes, which was significantly less than the night before (where it was 210 mins longer) and after (161 mins longer) the match.

Caffeine supplementation prior to and during competition leads to substantial increases in post competition salivary caffeine concentration. Although not significant, there was a trend for caffeine consumption to reduce sleep duration and increase sleep latency. Additionally, in regard to changes in salivary caffeine concentrations and wake time and time in bed, only minor relationships were found.

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Practical Takeaways

• Although a nice study, it is very difficult to control the habitual caffeine consumption of athletes within elite sporting environments. As such, the variance in post-match salivary caffeine concentration may be a consequence of higher basal levels of salivary caffeine, while the lack of standardisation relating to the type, timing, and dosage of supplementation in the current study should also be highlighted.
• As correlations between caffeine consumption and sleep characteristics were all non-significant, the authors rightly highlight that other factors are likely contributing to poor sleep characteristics for players including: exposure to floodlights, post-match alcohol consumption and sleep environments. I would also add from personal experience with rugby players, adrenaline of the match, muscle soreness and mobile phone use in bed are common issues I see in day-to-day practice.
• Practitioners working with athletes who consume caffeine before evening competition should look to provide educational programs to improve sleep hygiene practices. In practice, I have always seen better uptake of education when things are kept simple and easy to understand. Caffeine consumption timelines are a good idea for example.
• Finally, caffeine can be consumed through many forms including fluids (coffee, energy drinks etc), gum, gels and tablets. Working with your athlete to provide them with individualised strategies may result in a lower intake in the evening and support improved sleep characteristics. For example, if a player currently consumes an energy drink with 200mg of caffeine in, but actually feels they only need 100mg, then they would be better to take on a caffeine gum rather than the energy drink. Be careful with the actual caffeine content of coffee pods! They are not all what they say they are!

James Morehen’s Comments

“I liked reading this paper and it reminds me of many conversations that I have had with rugby players regarding caffeine intake. Of course, the focus on match play is to perform, and this results in many players consuming over 300 or 400mg of caffeine pre-match, about 3-6mg/kg body mass, which is aligned to a recent position stand and article below. It is not surprising that they struggle to sleep post-match.

“What do you do then? Do we ask players to not take caffeine so they can sleep better post-match or should we be allowing them to sleep in the following day and catch up on the sleep this way? This is certainly a strategy that is favoured by players; instead of getting them up early on a recovery day and bringing them into the club, allowing them to completely rest at home and lay in for as long as they want to. Hopefully studies in this area are completed soon to answer this research question.”

Want to learn more?

Then check these out…

Read this article
Read this article
Listen to this podcast
Read this infographic

Want more research reviews like this?

Every coach understands the importance of staying up-to-date with the latest sports performance research like this, but none have the time, energy, or even enjoys spending hours upon hours searching through PubMed and other academic journals. Instead, your precious time is better-spent coaching, programming, and managing all the other more important aspects of your job.

The solution…

The Performance Digest
The Performance Digest is a monthly summary of the latest sports performance research reviewed by our team of hand-selected experts. We sift through the 1,000+ studies published in the realms of sports performance every, single month and review only those which are important to you. Each monthly issues contains 15 research reviews in all of the following disciplines:

• Coaching Science
• Strength & Conditioning
• Technology & Monitoring
• Fatigue & Recovery
• Youth Development
• Nutrition
• Injury Prevention & Rehab

This comprehensive topic base ensures you’re constantly expanding your knowledge and accelerating your career as quickly as humanly possible. The reviews are also hyper-focused, 1-page summaries, meaning there’s no jargon or wasted time. We cut right to the chase and tell you what you need to know so you can get back to coaching.

Join the thousands of other coaches who read it every, single month. Click here to get instant access for free…

Dr. James Morehen

Dr. James Morehen is the Lead Performance Nutritionist for England Rugby and previously also worked as the Performance Nutritionist for Bristol Bears Rugby Union. He is a SENr registered performance nutritionist and works privately with both elite athletes and individuals through his business Morehen Performance Ltd.

More content by James

The post Caffeine and sleep: Does a pre-match coffee impact post-match sleep quality? appeared first on Science for Sport.

Energy availability in athletes is a growing area of focus for sports nutritionists. But how important is the concept of inadequate energy intake for both health and performance?

By Dr. James Morehen
Last updated: December 20th, 2023
6 min read

Original study

Charlton, B. T., Forsyth, S., & Clarke, D. C. (2022). Low Energy Availability and Relative Energy Deficiency in Sport: What Coaches Should Know. International Journal of Sports Science & Coaching, 17479541211054458.

Click here for abstract

Background & Objective

I have worked in professional sport for nine years now and have certainly seen elements of disordered eating and eating disorders with the athletes I have supported in rugby, football and boxing. I’m not convinced many of the athletes knew they had various traits of disordered eating patterns, nonetheless, let’s dive into this area a little deeper.

Since 1992, the term Female Athlete Triad has been used to describe the combination of amenorrhea, osteoporosis, and disordered eating. However, developments have been made and as of 2007, the Triad is now described as a disorder that features menstrual dysfunction, altered bone health and low energy availability (LEA) with or without an eating disorder.

In 2014, the International Olympic committee produced a consensus statement which encompasses the full scope of this symptomology and was given a new term, the Relative Energy Deficiency in Sport (RED-S). Importantly it was highlighted that this new framework includes males and recreational athletes. The video link below is an outstanding listen on this.

The purpose of this review was to synthesise available evidence and provide coaches with the scientific basis underlying the concepts of LEA disorders. An overview of RED-S is provided and importantly nutritional guidelines to help prevent LEA.

What They Did

The authors synthesised evidence from peer-reviewed studies published between 1986 and 2021 that they believe are essential for coaches to know so they can better guide their athletes and prevent LEA.

The review is split into the following sections:

1. The female athlete triad and relative energy deficiency in sport: diagnosis, mechanism, and prevalence
2. Performance and health impairments of LEA and RED-S which is then further broken down to:
   A) Hormonal and metabolic function
   B) Bone health
   C) Cognitive ability and mental health
3. Nutritional practices to help prevent LEA and RED-S
4. Monitoring athletes for risk of LEA
5. Supporting athletes at risk of LEA

What They Found

Practical Takeaways

James Morehen’s Comments

“All athletes are at risk of LEA but is it a problem for everyone? Some of the boxers I work with experience elements of under-fuelling, but this is strategically planned into their overall nutritional strategy to help them make weight. Personally, I think acute bouts of LEA are ok, but if this transitions into chronic periods of time, then that’s when the health and performance problems will arise.

“As nutritionists, we are uniquely positioned to be able to spot the early signs of eating disorders or disordered eating before these manifest into LEA and RED-S. I would encourage other practitioners to quickly get to know their athletes’ habitual eating behaviours at meal times and observe if these change from the norm.”

Want to learn more? Then check these out…

Watch this video
Listen to this podcast
Read this infographic

[optin-monster-shortcode id=”nhpxak0baeqvjdeila6a”]

Want more research reviews like this?

Every coach understands the importance of staying up-to-date with the latest sports performance research like this, but none have the time, energy, or even enjoys spending hours upon hours searching through PubMed and other academic journals. Instead, your precious time is better-spent coaching, programming, and managing all the other more important aspects of your job.

The solution…

The Performance Digest
The Performance Digest is a monthly summary of the latest sports performance research reviewed by our team of hand-selected experts. We sift through the 1,000+ studies published in the realms of sports performance every, single month and review only those which are important to you. Each monthly issues contains 15 research reviews in all of the following disciplines:

This comprehensive topic base ensures you’re constantly expanding your knowledge and accelerating your career as quickly as humanly possible. The reviews are also hyper-focused, 1-page summaries, meaning there’s no jargon or wasted time. We cut right to the chase and tell you what you need to know so you can get back to coaching.

Join the thousands of other coaches who read it every, single month. Click here to get instant access for free…

Dr. James Morehen

Dr. James Morehen is the Lead Performance Nutritionist for England Rugby and previously also worked as the Performance Nutritionist for Bristol Bears Rugby Union. He is a SENr registered performance nutritionist and works privately with both elite athletes and individuals through his business Morehen Performance Ltd.

More content by James

The post Energy availability in athletes: How important is the concept of inadequate energy intake? appeared first on Science for Sport.

There’s no doubt the link between cannabidiol and professional athletes is big and it’s happening right now. But what does the science — and the law — have to say?

By Dr. James Morehen
Last updated: March 1st, 2024
9 min read

Cannabidiol: A brief introduction 

In the sports nutrition world, unless you have been living underneath a rock the last few years, you would have heard about athletes either using or selling cannabidiol (CBD). In the United Kingdom (UK), England rugby players own companies selling it, while high-profile US soccer player Megan Rapinoe uses it in her training regime and promoted her sister’s CBD product company during a Forbes.com interview.

If Forbes.com isn’t big enough, the biggest sporting event of them all, the Olympics in Japan, was labelled by some media outlets as the first ‘CBD Olympics’. There were many stories shared of athletes using CBD in the months leading into the Games – for example, Rapinoe said she used CBD to boost her performance.

There’s no doubt the link between CBD and professional athletes is big and it’s happening right now.

The prevalence of use is large, and work performed here in the UK by a colleague of mine, Andreas Kasper, shows an alarming trend in professional rugby players. In their study published last year, more than 500 professional players were anonymously surveyed on their use of CBD and the reasons why they were turning to it. A quarter had either tried CBD during their playing career or were currently taking it, with almost 40% of players aged above 30 being in this category. Many of the players were getting their information about CBD from either the internet (73%) or a teammate (61%). This wouldn’t be so bad if they were cross-checking this information with the club nutritionist or dietician, however only 16% of players were seeking help with qualified practitioners.

It baffles me why athletes wouldn’t seek the advice of qualified individuals within their club. This is addressed in the paper by Kasper et al., where they explain this might be occurring because athletes do not have complete trust or feel they cannot approach practitioners to ask for advice. Time for us nutritionists and dieticians to build better trust with our athletes, so they feel comfortable enough to approach us in these situations.

Is cannabidiol oil legal?

Evidence suggests CBD use has increased exponentially which is likely due to both its removal from the World Anti-Doping Agency (WADA) prohibited list (WADA, 2018) alongside the evolving legal landscape. Without going too deep into the political side of things, the legal landscape is complicated and varies from country to country, and within the US,  even varies from state to state.

In the UK, CBD is currently legal to be sold as a supplement providing the CBD comes from hemp, that the final product contains < 1 mg of THC, and that no medical claims are made surrounding its use. The UK has also classified CBD as a ‘novel food’, meaning companies wanting to continue to sell CBD were required to have submitted and had their Novel Foods Application validated by March 31, 2021.

What is CBD?

The cannabis plant itself contains more than 140 cannabinoids, with the most notable being tetrahydrocannabinol (commonly referred to as THC) and cannabidiol.

THC has been identified as the main cannabinoid responsible for the psychotropic effect of cannabis. So, if you have ever smoked it and felt a little light-headed, that was the THC! But CBD itself has been cited as a non-intoxicating constituent of the cannabis plant with potential therapeutic value.

The endocannabinoid system (ECS) aims to regulate homeostasis within the body and is vital in modulating the central and peripheral nervous systems, as well as the gastrointestinal tract, the endocrine, immune and reproductive systems. When consumed orally, cannabinoids are metabolised in the liver and trigger some clever little receptors called CB1 and CB2 which then work their magic in activating many kinases and channels.

Recently, Professor Graeme Close has been conducting some interesting studies in this area of research. Graeme is a professor of human physiology from Liverpool John Moores University in England and in his younger years was a professional rugby player. He has become very excited by CBD in the past few years, although in an article he published he admitted the research on how CBD works within the body was still not well understood. Additionally, due to many compounds within the cannabis leaf, there are many potential interactions which may be occurring which we do not know enough about. For example, the perceived pain relief effect reported in products containing CBD might be due to THC being present, rather than CBD alone. But the therapeutic potential of cannabinoids in a sporting context is particularly exciting given the ability to interact with the body’s own endocannabinoid system.

So why are athletes so keen to use CBD?

You only have to Google ’athlete and CBD use’ then hit the news tab to see many articles with current or retired athletes partnering with CBD companies. From basketball players to boxers, it seems one of the attractions for athletes wanting to get involved in this industry is due to its valuation of $US55 billion by 2028.

But why is this such a booming industry? Primarily because there are many claims of CBD helping with pain, sleep, anxiety and even concussion. If you are a nutritionist or even sport scientist, at some point in your career you would have spoken to an athlete regarding one of these areas. With this in mind, let’s see what evidence there is for each one of them.

Pain

Symptoms of exercise induced muscle damage (EIMD) and impact induced muscle damage (IIMD) are common in most sports. For example, runners who spend hours on end pounding the tarmac will experience EIMD from frequent and consistent muscle contractions. Athletes who are involved in physical collisions sports like rugby, American football and ice hockey, will experience EIMD but also IIMD.

Think about this… a typical rugby player weighs about 100kg – this is the same as a commercial fridge. Normally one player will run into two or three defensive opponents trying to tackle him and get the ball. This is 100kg running full steam into 200-300kg of human wall, so a combined impact of 300-400kg. Is it any wonder collision-based players experience pain after competition?
One route to try and support recovery from pain is through nutrition. Protein, amino acids, polyphenols, omega-3 fatty acids, creatine and vitamins C, D and E have all been shown to support recovery from pain, with beneficial supporting literature.

Outside of nutrition, non-steroidal-anti-inflammatory drugs (NSAIDs) are also regularly taken by athletes in an attempt to try support pain management, however if consumed chronically, NSAIDs can upset the stomach, cause headaches and constipation – none of what we want for our athletes! This is where CBD enters the arena as a potential alternative pain-relieving option.

Interestingly however, the majority of studies which have investigated CBD on models of pain have been completed in animal models. Research with humans is limited and at present it is too early to support CBD use as an alternative to standard pain medication in athletes.

Sleep

Sleep disruption (less than seven hours of sleep) appears to be more common in athletes than the general population. Many professionals working with athletes have had countless conversations in regards to their sleep hygiene (i.e., phone use prior to bed, bright lights in the bedroom, caffeine consumption in the evening). Sleep is an obvious area to improve to help athletes recover from their training and competitions.

Although many athletes have shared anecdotal reports of sleep benefits from CBD consumption, in 2018 a placebo-control, double blind cohort study suggests there is no benefit, or even negative effects of CBD on sleep. The summary here then is that before we can be confident of any possible beneficial effects of CBD on sleep, more placebo-controlled studies need to be completed.

If you are interested in improving sleep with your athletes outside of CBD, then check this fantastic article out.

Anxiety

Being a professional athlete is nerve-racking at the best of times, let alone during major competitions or important matches. This in turn can result in athletes being over-aroused, not wanting to eat and losing sleep. Even one of the best tennis players of all time, Roger Federer, gets nervous and anxious!
Like sleep, at present, the literature regarding CBD and anxiety is ambiguous. Outside of CBD use, practitioners may suggest visualisation techniques, rehearsals or athletes participating in more practice to master a skill they may be anxious about. One of the world’s best football players ever, Cristiano Ronaldo, is a big fan of visualisation to improve performance.

Concussion

Imagine being blindsided (great film by the way) by a tackle in rugby or American football. Or crashing your F1 vehicle into a wall at 150kmh. The violent blow to the head or shaking results in dramatic changes in neurochemicals inside the brain, which cause the common side effects of concussion – for example, headaches, dizziness, nausea, and poor balance to name a few.

Unfortunately, although some media outlets claim concussion can be alleviated by CBD use, there has actually only been one study directly assessing the effects of CBD supplementation on the treatment of brain injury. Guess what – the study was conducted in mice! Now although our furry little friends might get a concussion from running into three of their furry little friends, I think you will agree with me that this cannot be translated into the human population just yet. Although the mice study may show reduced inflammation in their little brains, the exact mechanism by which CBD works is still not understood.

Although this is an exciting area of work, much more research needs to be done, particular in human trials.

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Anti-doping rule violation risks

The reason Sha’Carri Richardson was banned for the Tokyo Games was due to her urine sample containing THC levels above the current threshold. According to the World Anti-Doping Association, any analytical finding above 150ng/ml in urine results in a rule violation and subsequent punishment. This is where it can be a bit of a minefield in the industry at the moment.

Although many companies state they have CBD products with 0% THC on the label, there are many other cannabinoids which remain banned by WADA in and out of competition. For the athlete to be completely sure the product is safe to use, it needs to be THC-free and free from all the other cannabinoids that are currently prohibited.

A nice paper last year showed how only 15% of commercially available products in the US were below the < 0.3% THC maximum limit, posing serious risks to athletes in America. Additionally, batch testing of THC-containing products is limited across the globe. Combined, this should be enough to worry athletes and support staff on the risks involved when consuming CBD products via oil, sweets or cream

Dare to try it or wait for more research?

At present there is limited evidence on the proposed positives of CBD use with athletes. Although there is some research regarding the analgesic, antioxidant, sleep, and neuroprotective benefits of CBD consumption, there are still far too many risks involved. For example, the accumulation of CBD storage in tissues from varying products is a big worry as it increases the chances of failing a doping test, alongside the potential for inadvertent doping. Finally, if you are taking a product which hasn’t labeled the dosage of THC correctly then there is a real risk of potential toxicity and side effects.

What is clear is, the use of CBD in sporting circles is only likely to increase. As practitioners we must keep an eye on the research and literature to ensure we are up to date with the evidence. If you are working with aging athletes, they may be the individuals more likely to try CBD in the quest to try and support recovery as they get older.

In terms of scientific research, this is an exciting area moving forward but it does require more human placebo-controlled studies to be conducted. However, given the current highlighted risks and red flags associated with CBD products for professional athletes, it is a product I would suggest staying away from for the next few years!

Dr. James Morehen

Dr. James Morehen is the Lead Performance Nutritionist for England Rugby and previously also worked as the Performance Nutritionist for Bristol Bears Rugby Union. He is a SENr registered performance nutritionist and works privately with both elite athletes and individuals through his business Morehen Performance Ltd.

More content by James

The post Cannabidiol: What is it and why are more athletes using it? appeared first on Science for Sport.

It seems almost all athletes may potentially benefit from caffeine supplementation, with aerobic sports benefiting most.

By Dr. James Morehen
Last updated: February 29th, 2024
12 min read

Caffeine and sports performance: Is it worth the hype?

Your first sip of that Starbucks Grande caramel oat milk latte on the way to work, that bite of Dairy Milk chocolate at lunch, the ice-cold cola drink with dinner, that warm cup of Earl Grey before bed, and even that cold and flu tablet you take to tackle your blocked sinuses and sore throat in the winter … there is one common ingredient hiding within these drinks, food and medication. Caffeine! Caffeine is everywhere.

With records of its consumption dating back to the 16th century, and an estimated two billion cups of coffee drunk worldwide every day, caffeine is arguably the most widely consumed performance-enhancing drug on the planet. After it was removed from the World Anti-Doping Agency banned list in 2004, its use has been steadily growing across a wide variety of sports including aquatics, athletics, boxing, judo, football, and weightlifting, but the sports found to have the highest concentration of urine caffeine concentrations are cycling, athletics, and rowing.

But what does caffeine actually do, and is it really worth the hype?

The best-known source of caffeine is coffee, although it’s also found in a range of other foods and drinks such as black tea, green tea, dark chocolate, yerba maté and of course added to energy drinks and pre-workout supplements. In its purest form, it can also be taken as tablets, in chewing gum, or even nasal sprays (seriously!). No matter which forms it is consumed in, the effects remain broadly the same.

How does caffeine work?

Before we delve into the nitty-gritty, it’s important that you understand what caffeine is and how it works in the body.

Caffeine is a psychoactive drug, meaning it directly affects the brain. Specifically, caffeine is classed as a stimulant since it increases (or stimulates) the activity of the nervous system and brain. This explains the feelings of wakefulness or alertness that most of us associate with caffeine.

The most studied and well-known of these effects is caffeine’s ability to temporarily block a molecule called adenosine. As we exercise, think, and go about our daily lives, the level of adenosine slowly builds up in the brain, binding onto receptor sites. The more adenosine we have bound onto these sites, the more tired and drowsy we feel, and interestingly, the more susceptible to the pain we are. Where does caffeine come into the story? Caffeine has a very similar structure to adenosine, meaning it can bind to those receptor sites and block adenosine. Less adenosine = less mental tiredness, and less pain. Sounds promising, right?

The second effect is directly within the muscle itself. To make a muscle contraction happen, we need calcium to move around in the muscle fibre. Caffeine is able to make that movement happen faster, so in theory that will help increase the force of any given contraction. Research into this particular effect is strong, but the experiments were mostly done using extracted muscle fibres in Petri dishes. Using this method allows a dose of caffeine to be used that is typically much stronger than what is normally consumed by humans in real life. To this end, we need more research before we can say whether this effect is actually useful in practice.

Fat burning is the third supposed effect of caffeine. Caffeine itself can stimulate the breakdown and release of triglycerides (stored fat), to free fatty acids which can be used as a fuel. If the body is able to use more fats as fuel, it uses less glycogen (the stored form of carbohydrate in muscles) meaning we may have more carbohydrates available for later on during the exercise session, delaying the onset of fatigue. Caffeine also increases the production of a group of hormones known as catecholamines, which include adrenaline. These hormones can also break down triglycerides, leading to more free fatty acids available as fuel. Research on whether or not caffeine increases fat burning to any appreciable degree is conflicting, and even more so when it comes to whether or not it is likely to improve performance. It seems to be very person-specific and may be due to genetics. However, even if there is a benefit for some people, the likelihood is that any fat-burning effects are tiny.

Does caffeine enhance athletic performance?

Yes, although there is a very wide variation in results from almost all trials investigating caffeine.

One meta-analysis (a type of review that pools together all the results of several research studies) using data from 56 different time trials found the percentage difference in performance was up to 15.9%. They also found the effect of the caffeine supplementation was better the longer the duration of the time trial. Given we know caffeine acts directly on systems of fatigue and pain in the brain, it would stand to reason that the longer an athlete has been exercising, the more fatigued they would be and the more pain they are likely to experience, so the greater the effect of the caffeine.

Muscular endurance is particularly important for sports such as rowing and swimming. Although caffeine has been shown to have a positive effect ranging from 6-7% on muscular endurance, other studies have shown no benefits. This is likely due to the difference in methods employed in research designs. Personally, I am a huge fan of caffeine for performance and I use it for endurance-based athletes.

Investigations focusing on caffeine and strength are slightly more clear-cut, with three different meta-analyses all reporting an ergogenic effect of 2-7%. This is likely to be applicable to athletes competing in powerlifting and weightlifting, and these athletes are among some of the highest users of caffeine.

So although most sports could potentially see a performance improvement with caffeine supplementation, it’s likely aerobic sports of longer duration benefit most, followed by aerobic sports of shorter duration, with a smaller effect seen in sports with a high explosive strength component.

The lowest effect seems to be seen in repeated sprint bouts, as would be found in most team sports, for example. But when it comes to team sports, there is a huge element of cognitive ability and mental fatigue, not just the purely physical elements we’ve mentioned so far. Most of the data looking at cognitive ability, fatigue, and caffeine comes from military studies – understandable really, since for those guys and girls, it’s not just about performance but also potentially life or death! The main take-home from those studies is that caffeine is likely to help with concentration and alertness during periods of sleep deprivation and stress. Of the available research translating that into team sport performance, passing accuracy and agility might be slightly improved but the general consensus from the International Society of Sport Nutrition on caffeine and exercise performance is that caffeine would not be more effective than having had a good quality sleep. When that hasn’t been possible for whatever reason, caffeine may help slightly.

Caffeine dosage for performance

As can be seen from all of these results, the effect of caffeine on each person is highly individual and is largely mediated by our genes. Specifically, the gene that codes for the CYP1A2 enzyme – I know, catchy name! Essentially that gene means we either break down caffeine really quickly, so we need a higher dose to have an effect, or it takes ages to break the caffeine down so we need a much lower dose for a large effect. This video explains it all really neatly.

Caffeine doses, timing, and how to take it

The doses of caffeine used in these trials all range from 3-6mg per kilo of the athlete’s weight. There doesn’t seem to be any performance benefit of going above 9mgs per kg, but there are potentially quite a few drawbacks including heightened anxiety, gastrointestinal issues and a rapid, potentially irregular heartbeat.

For a 70kg athlete, 3-6mg per kilo of the athlete’s weight would be 210mgs – 420mgs, which equates to roughly 2.5-5 shots of espresso. However, the amount of caffeine in coffee can vary dramatically, even if you get the coffee from the same place and order the same thing each day. Therefore it’s probably not the most reliable source of pre-training caffeine if you want to be precise about it!

Coffee also comes with its own drawbacks, in that it contains a whole load of other compounds besides the caffeine and can potentially be quite irritating to the gut. Combine that with competition day nerves … and an athlete may find themselves more than a little distracted!
Logistically, it can be a bit of a nightmare for athletes to make sure they find and can consume the coffee at the right moment, and as coffee is usually something we have hot, it’s not always great for summer competitions or trying to drink quickly during a warm-up.

More reliable, easier-to-take sources of caffeine include anhydrous tablets, caffeine chewing gum, pre-workout shots, energy drinks, and caffeine in gels and energy bars. Caffeine can also be taken as mouth rinses and nasal sprays, but the jury is still out as to whether they are as effective. However, as with any supplement, it’s the dose that makes the poison, so athletes need to be careful they are getting the right overall dose – especially if they’re combining different sources.

General guidelines for caffeine suggest taking it about 60 minutes before exercise, as it needs to be digested, absorbed, and pass through the liver before it can start to have an effect on the central nervous system. It usually takes about 20-30 minutes before the effects are noticeable, and about 60 minutes before the blood concentration reaches its peak. Chewing gum tends to be absorbed faster, as it doesn’t need to be digested through the stomach and is instead absorbed through the membranes in the mouth, as described in this article.

Which form of caffeine is best for each athlete can vary enormously, and comes down to things like:

• Is it easily available at the competition, or in the country where the athlete is competing?
• Is it easy to travel with? Liquids can get heavy if an athlete is away for several back-to-back competitions.
• If the athlete is travelling with hand luggage only, can it be taken on the plane?
• Does it contain any other ergogenic aids which the athlete may also be taken separately?
• Is it cost-effective?
• When will the athlete have time to take it before the competition in relation to pre-competition commitments?
• Does the athlete have access to their bag 60 minutes before competition, or is it away in a locker room? In which case would they need to have it in a pocket or similar?
• Is it Informed Sport tested?

‘Me-search’ vs. research

What’s important to remember as we start thinking about putting all this into practice is that a lot of the research carried out is under tightly controlled lab conditions. When we’ve got athletes out competing in a variety of different sports, the situation is rarely that controlled; plus all athletes are different, with different personalities – what works for one may not work for another.

This highlights the importance of what I call ‘me-search’, vs. research, which is the importance of using research as a starting point and then having each athlete try it out, test the effects and tweak the protocol until the greatest performance benefit is found for each individual. Essentially, athletes should conduct their own mini-research studies on themselves.

When working with a new athlete, I always start with the research literature as a base guideline, and then through trial and error during training sessions we figure out what dose works best for them, and then once we’ve got that nailed, we think about which form would be best to take it in, bearing in mind all the factors outlined above.

When deciding what starting dose to use, some of the considerations might be whether:

• The athlete is used to drinking coffee or having caffeine regularly already. If not, we’d start with a lower dose.
• They tend to be anxious or are prone to getting nervous before competitions. If this is the case, a lower dose may be required (i.e. 1-2 mg.kg-1)
• The exact nature of the sport; one of the sports I work in is biathlon where the athletes have to do a cross-country ski race, interspersed with target shooting. The caffeine might help a lot with the ski, but for some athletes, it increases their heart rate and anxiety to the point they can’t shoot straight!
• If it’s possible or not to have a top-up during the race or competition.

The second consideration would be the timing of the dose, and whether to split it into several smaller doses during the course of the event. For longer endurance events such as one-day stage cycling races or long-distance triathlons such as Ironman, the best effects are often found when the caffeine is taken during the later stages of the race. Once the athlete has reached the point of fatigue where their heart rate remains largely stable and refuses to rise when a harder effort, such as a hill climb is needed, is when lots of athletes decide to start using caffeine to help them push through to the end. Triathletes are notorious for downing cans of flat cola during the later stages of races.

Team sport athletes may want to consider consuming three-quarters of the dose of caffeine 60 minutes before the match and a top-up right at the beginning of the half-time break. The top-up would then hit peak levels in the blood (for most people) midway through the second half when many players start to feel the decline in performance due to fatigue.

The last, but by no means least important consideration, would be at what time the match/competition is being held. If the event is to be held later in the day, having a high dose of caffeine is likely to disrupt sleep after the competition. Given that one of the key factors in promoting recovery is good quality sleep if an athlete then has to compete again the next day, it is likely the caffeine will have a detrimental effect on the subsequent performance.

Practical examples of using caffeine for sports performance

As examples of how a caffeine strategy for performance might work in practice, here are two examples of cross-country ski athletes who competed in the Beijing Winter Olympics.

Cross-country endurance skier

The first example is a female athlete who weighs 49 kg. She doesn’t usually drink a lot of coffee and tends to be quite anxious, especially before big races. She competed in two events: the first was a shorter distance, full-throttle race where she wasn’t able to top up with either carbs or caffeine during the race. For that race, she would take:

• 100mgs in tablet form one hour before the race
• 80mgs in a carb gel about 30 minutes before the race, during the warm-up.

Her second race was 30kms and usually takes approximately 1 hour and 20 minutes to complete. She was able to take on more carbohydrates and caffeine at two points during the race, which her coach can hand to her as she’s racing. For this race, she would have:

• 100mgs in tablet form 30 minutes before the race.
• 80mgs in a carb gel after 10kms.
• 80mgs in a carb gel diluted in some water after 20kms.

Note: It’s extremely difficult to consume gels or drinks while cross-country skiing (it can get very messy!) so it is unlikely she was able to ingest the full 80mgs each time.

Cross-country sprint skier

The second athlete is a male weighing 76 kg. He is a very regular coffee drinker, habitually consuming up to five cups a day. He’s a super chilled-out guy, although he does get a bit nervous before the qualification round. He competes in the sprint event which comprises the qualification heats, followed by quarter-finals two hours later, semi-finals 30 minutes after that, and the final 20 minutes after the semis. He will cut down his caffeine intake for three days before the race, but not cut it out completely to avoid any withdrawal effects such as headaches, so he can really feel the effect when he does take the caffeine.

His strategy was as follows:

• No caffeine before the qualification round.
• Can of flat Red Bull (80mgs caffeine) + 100mgs caffeine tablets immediately after qualification up to 65 minutes before the quarter-finals.
• 50mgs in chewing gum 30 minutes before the quarter-finals.
• 80mgs in an energy gel 20 minutes before the quarter-finals.
• 80mgs in an energy gel immediately after the semi-finals.

A word of warning before using caffeine for sports performance

Please be aware if you or your athlete are considering the use of caffeine, make sure you safely follow evidence-based guidelines. Even better, work with a professional nutritionist/dietician to support you through the process.

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Dr. James Morehen

Dr. James Morehen is the Lead Performance Nutritionist for England Rugby and previously also worked as the Performance Nutritionist for Bristol Bears Rugby Union. He is a SENr registered performance nutritionist and works privately with both elite athletes and individuals through his business Morehen Performance Ltd.

More content by James

The post Caffeine and sports performance: Pros, cons and considerations appeared first on Science for Sport.

The majority of combat sport athletes will go through a period of short-term weight loss prior to a fight. Why do they endure this, and can it be done safely?

By Dr. James Morehen
Last updated: February 29th, 2024
11 min read

Weight cutting: Why do some athletes endure it?

Following eight weeks of strict, tightly controlled nutritional intake, combined with tens of thousands of pounding steps during the cold morning runs, you find yourself at the start of fight week. This is the week elite fighters should love – the build-up, the electric energy around the city and the media attention ramping up as they come ever closer to strapping their wrists and striding towards the ring with their chosen anthem exploding out of the stadium speakers.

In the ring, every heartbeat grows quicker and louder as the fighters stare across at their opponent – the aim of the next 36 minutes is to hit them with devastating force. This is combat sports!
Although it is the fight that occurs inside the ring that decides who has their hand raised at the final bell, there is a catalogue of considerations, or worse, catastrophes, that each fighter must navigate beforehand to ensure preparedness for battle. The most common of which is weight cutting.

You might find yourself asking: “do combat sport athletes really need to cut weight? Why can’t they just fight at the weight they walk around at every day?” Well, you’d think this is the most sensible approach, yet the majority of combat sport athletes will go through a period of short-term weight loss prior to a fight. Some will even put their body, mind and soul through hell and lose a dangerous 10kg in 24 hours!
Weight cutting done incorrectly can result in serious consequences, and in some devastating situations, even death.  So why do they do it? In my recent Coach Academy mini-course, I discuss this in more detail, but for now, let’s explore some of the main points around weight cutting and explore a couple of strategies to maximise the benefits while minimising associated risks.

Before we really dive in … a warning

Please be aware: if you or your athlete are going to make weight for competition, make sure you safely follow evidence-based guidelines. Even better, work with a professional nutritionist/dietician to support you through the process.

The weight cut, and the 3 Ts of nutrition

In very simple terms, weight cutting is the process of decreasing body weight during an acute period of time. However, prior to any weight cut (the final seven days prior to competition) starting, the manipulation of body composition is best done gradually over time. Essentially, before the final week of training camp and before any acute weight loss occurs, the goal is to reduce fat mass while maintaining or even gaining lean mass (muscle). Basically, if you are carrying extra fat mass, this is the time to get rid of it and ‘lean out’.

For professional boxers, body composition changes substantially over time. Some hot-off-the-press data of mine (see figure 1 below) shows how a boxer’s body composition fluctuates over time, but also how important it is to have a fighter at their ‘optimal’ body composition when entering the final seven days prior to weight cut.

A key concept I discuss throughout the mini-course and in many podcasts is the 3 T’s of nutrition – Timing, Type and Total. Put simply, these refer to the time of day you are eating, the type of food or fluid you are consuming and the total amount of both.  If you and your combat sport athlete can understand how the 3 T’s work together, like three cogs in a very well-oiled machine, then you will be in a great place to safely improve body composition prior to any acute weight cutting. Better still, this 3 T’s model also applies to the training that combat sport athletes perform. So, again, what time of day are you exercising? What type of exercise are you performing? And for what duration?
If you dovetail these two models together, on a practical level, you will be implementing the framework: “fuelling for the work required.” In short, this is when pre-planned nutritional intake is aligned to the training demands of your day to elicit both the correct training adaptations and body composition targets. Even Premier League clubs adopt this framework for professional football players.

Prior to competition, combat sport athletes have their body mass verified at the official ‘weigh in’ to ensure they meet the weight requirements of their competitive division. Within combat sports, this is known as ‘making the weight’. The actual time duration between the weigh-in and stepping into the ring for competition differs between sports. However, a recovery period of at least three and up to 24 hours exists among the Olympic combat sports.

If done correctly, the weight cut should be a planned, prepared and easy process to perform, which results in a well-nourished, well-hydrated and happy athlete in the ring. If implemented poorly, with minimal evidence behind it, or by individuals who are not registered nutritionists/dieticians, the athlete can struggle and experience distress. Essentially, get the recovery from ‘making the weight’ wrong, and it could result in a shocking performance in the ring and an easy fight for your opponent. Even professional boxers get this wrong at times. We just have to turn our attention to Kid Galahad having to take his underwear off to make the weight at his official weigh in for his fight against Eddie Hearns.

FIGURE 1. Body mass, fat mass, fat-free mass, and body fat percentage changes in a professional boxer over time during 11 contests.

What are the benefits of cutting weight for a fight?

Many combat sport athletes believe cutting weight before a fight results in advantages over their opponent when in the ring. Mainly, the ability to rebound in weight, enter the competition heavier than their opponent and use this to their advantage in clinches or up against the ropes. Interestingly, studies exploring how weight manipulation strategies affect competitive outcomes in boxing are inconclusive.

With this in mind, it really does depend on what the fighter prefers to do, what has been practised in training and what works best. Irrespectively, ensuring individual strategies are implemented with each fighter is key, rather than using a cookie-cutter approach for all.

In my experience, making sure your fighter is well-nourished and well-hydrated with plenty of room for an acute weight loss to occur should ensure they enjoy the entire process. They will also enjoy the weight regained, as they will replace fluids lost and increase their energy ready for fight. Always remember, a happy fighter is a dangerous fighter. The opposite of this is a fighter who enters the final week of acute weight loss dehydrated and having under-eaten – they will already be struggling and, in most cases, should not put their body through the extra stress of trying to lose weight. This can be dangerous and should be reconsidered.

How much weight is too much weight to cut?

This is the golden question, and it is very difficult to put a definite figure on it. Firstly, where possible, you should always assess body competition using standardised measurement methods and regularly and correctly collect body weight. This will give you a far greater insight as to how much body weight needs to be lost in the final few days.

In the week prior to weigh-in, the current literature shows fighters commonly lose mass which is either greater than or equal to 10% of their own body weight. For example, some fighters who weigh in at 70kg might lose 7kg in the final week before weigh-in. However, as mentioned, this is very individual-specific, and while there is no single ‘ideal’ acute weight loss target, research suggests that under some conditions, a loss of 5–8% body mass may be possible, with an acceptably small impact on health and performance. Again, the starting point prior to acute weight loss should represent body mass associated with a fully hydrated, well-nourished state, offering plenty of opportunity for meaningful manipulation of gut content and body water.

It is widely accepted within the industry and literature that decreases in body mass greater than 10% in the final few days prior to competition can be dangerous and should not be attempted. For those of you who would like to view what it looks like to make the weight this way, I would draw your attention to these two video clips:
Weight cut: Can I lose 10% of my body weight overnight?
Aspen Ladd struggles to make the weight

Rocky’s Run – a snapshot of a pro

In my recent publication, I present data showing an approximate 5kg decrease in body mass during the final five-day period prior to the official weigh-in (Figure 2).

Figure 2. Changes in body mass during the seven days before the official weigh in, weigh in day and contest day.
This was typical of the way professional boxer Rocky Fielding made weight for the 11 camps that we worked together over the past four to five years.

You can see how Rocky was still above 80kg the day before the weigh-in and lost between 3-4 g in the final 24 hours; this represented about 5% of his total body weight.

READ MORE: THE SEVERE, DETRIMENTAL EFFECTS OF MAKING WEIGHT THE WRONG WAY
In particular, you can see across five contests, his average weight loss achieved via acute weight loss strategies during the final seven days was 3.7kg and represented 4.7% of his body weight (Table 1 below).

How to minimise the risks of cutting weight

There are many ways in which body mass can be reduced during the final few days and hours prior to making the weight. If done correctly, there should not be any real risk involved in the cutting of weight. Indeed, a combination of the following methods can all work together to see a drop of between 1-8% of body weight prior to weigh-in. If you would like to read about this in more detail, then I recommend this fantastic paper by Reid Reale.
Gut content manipulation

Body water change

Sweating methods

Utilising the above methods can aid combat sport athletes to make weight safer, providing they enter the start of fight week in a well-nourished and well-hydrated state. The following strategy is just one way they could be implemented and is highly dependent on the athlete’s body mass at the start of fight week before they begin making weight. The below is a guide based on an athlete who is 3-4kg over the weigh-in weight.

Day 5

Regular fibre intake, regular sodium intake, normal fluid intake, normal carbohydrate intake

Day 4

Regular fibre intake, regular sodium intake, normal fluid intake, normal carbohydrate intake

Day 3

Regular fibre intake, regular sodium intake, normal fluid intake, normal carbohydrate intake

Day 2

Low fibre intake, low sodium intake, normal fluid intake, moderate carbohydrate intake

Day 1

Low fibre intake, low sodium intake, moderate fluid intake during the day, low fluid intake in the evening, low carbohydrate intake

Weigh-in day

Low fibre intake, low sodium intake, low fluid intake, check weight and sweat as needed
Want to know more?
If you want to know in more detail how to implement a correct weight cut during the final few days before a fight and what this looks like with food and fluid examples, then I would recommend you check out my mini-course.

Before we go – stop what you’re doing and get professional advice!

As a general rule of thumb for weight-cutting, ask yourself the question: “Is my athlete well hydrated, well-nourished and has less than 10% body weight to drop in the final 5-7 days?” If the answer is yes, then you are in a good place to enter the final week of acute weight loss and making the weight. If your athlete is already dehydrated and has dropped their energy intake, I would seriously reconsider progressing with the weight cut and would personally advise against it.

If you do have an athlete who is in a great starting position for the weight cut but then experiences headaches, poor sleep, and generally feels unwell, then again, I would stop the weight cut and consider pulling them out of the upcoming fight.

It is important we look after the health and wellbeing of our fighters and are confident they are in a healthy position to go ahead and perform in the ring.

One for the road – key lessons of weight cutting

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Dr. James Morehen

Dr. James Morehen is the Lead Performance Nutritionist for England Rugby and previously also worked as the Performance Nutritionist for Bristol Bears Rugby Union. He is a SENr registered performance nutritionist and works privately with both elite athletes and individuals through his business Morehen Performance Ltd.

More content by James

The post Weight cutting in combat sports: What is it and how can you minimise the risks? appeared first on Science for Sport.

Many people and athletes choose to consume alcohol but what exactly does the science say in terms of its effect on performance, recovery and nutrition?

By Dr. James Morehen
Last updated: February 29th, 2024
8 min read

Alcohol and athletic performance: cheers to that! Or maybe not…

After 120 minutes of fierce competitiveness and palpable tension, the score is tied. The European Cup final will be decided in the tensest possible way – the dreaded penalty shoot-out. To make matters even worse, you’re the goalkeeper. After a rollercoaster of emotion filled with a world-record number of loop-de-loops, it comes down to one final kick. As you bounce up and down on the goaline preparing to make the most important decision of your football career, you gaze into the 19-year-old midfielder’s eyes standing opposite you. You can see the hope of an entire nation weighing heavy on his mind. He’s going right. Within a split second, you’ve lunged to your left and swatted that ball away as if it were a blowfly stunned in mid-air by fly spray. Pure elation ensues. It’s time to crack the beers and pop the champagne to celebrate. Surely a few drinks won’t do any harm after such a historic win, right?
It was pretty evident that the Italians were celebrating with a few beers after their win over England. Beer in hand, Leonardo Bonucci even said in his post-match interview he would “drink everything tonight”. With my background in rugby, I have also seen many players consume a beer or two in the changing room after a normal win on a Friday night. Not to mention weekend drinks outside of team responsibilities.

But, is alcohol bad for athletic performance and recovery?

A brief whistle whetter

In 2006, Ronald Maughan and Susan Shirreffs published a manuscript in the American College of Sports Medicine titled: The Effect of Alcohol on Athletic Performance. Unsurprisingly, they state within the first line of their introduction that: “alcohol is not an essential part of the human diet … although regularly consumed by a large part of the world’s population”. A large chunk of this consumption could have been the 13 million pints (1,000 pints ordered every second) consumed by England fans during the final of the European Championships.

While alcohol is a significant source of energy — providing 7kcal per gram (carbohydrate and protein = 4kcal per gram and fat = 9kcal per gram) — it is not the preferred choice to fuel athletic performance.  Carbohydrates are much better at fuelling the body than alcohol. In fact, alcohol has been shown to impair performance of endurance exercise mainly because of the effects on metabolic, cardiovascular and thermoregulatory function. These are all physical performance variables, but what about the cognitive performance variables of reaction time, fine motor control and levels of arousal and judgment? Yep, you guessed it, all of these are impaired during training and competition as a result of alcohol consumption too.

On the front line, any athlete who needs to perform intense physical activity and make decisions under pressure should not be consuming alcohol pre-competition. Put simply, this will not help performance.

A shot of science

Let’s dive a little bit deeper into the effects of alcohol on human physiology. Alcohol consumption inhibits the role of calcium within skeletal muscle, mainly leading to the impairment of excitation-contraction coupling and decreasing strength output. Additionally, alcohol consumption may compromise the integrity of skeletal muscle cells resulting in a greater rise in creatine kinase, which is a marker of muscle damage. In regard to thermoregulation and hydration, early reports identified alcohol as a potent diuretic, where a 10mL excess urine production was evident following each gram of ethanol consumed. Alcohol can also act as a peripheral vasodilator (these are chemicals that cause your blood vessels to widen, increasing blood flow to the outer parts of your body) resulting in increases in fluid loss through evaporation and causing even further dehydration.

For an athlete who needs to maximise glycogen usage for performance (remember back to biology 101 – glycogen is the fuel for our muscle, like petrol in a car), I’m afraid alcohol isn’t going to do you any favours considering it reduces muscle glycogen uptake and storage. In simple terms, alcohol will reduce your ability to use glycogen as an energy source for performance.

The knock-on effect of alcohol consumption is it is also detrimental for protein synthesis. Protein synthesis is the process of cells making proteins and is super important for muscle growth, adaptation and recovery. In particular, alcohol consumption results in poorer muscle recovery after exercise. The reason for this is because fuel is important for muscle recovery, and so in combination with its direct effect on protein synthesis, alcohol hampers fuel availability resulting in sub-optimal recovery.

Finally, in regard to the neurological effects of alcohol, it is well accepted that it acts as a depressant and reduces central nervous system excitability and activity. For those who do enjoy a drink, you will know what this feels like the day after drinking – you feel sluggish, struggle to make decisions and sometimes feel irritable. Alcohol is also dose dependent, so the more you drink, the worse your balance, reaction time, visual search, recognition, memory and accuracy of fine motor skills become. The next time you are trying to search out and remember the name of the person you met at the bar, think about how alcohol is going to hamper your chance of a successful outcome to this situation. So the next time you have an important training session or game, reconsider your idea of “just having one”.

Impact on athletic performance

When considering how alcohol affects athletic performance, again let’s dive a little deeper.

Interestingly, earlier studies on aerobic performance and 5-mile treadmill time trials found no significant consequence of alcohol on performance. Contrastingly and not surprisingly, literature does show detrimental effects on endurance performance. What has been agreed is that a threshold exists whereby alcohol intoxication of 20mmol/L of ethanol results in performance decrements. To put this into more practical terms, the legal limit for driving is 0.05% of blood alcohol content circulating in the blood. This equates to 11mmol/L which is slightly lower than the threshold mentioned above. So, think about the last time you may have had one pint and then driven your car, but on reflection felt like you shouldn’t have because you felt a little light headed!
In regards to anaerobic performance, there has only actually been one study which has investigated and shown a negative effect of alcohol on sprint performance. The main take home from this study conducted with five sprinters was that alcohol dosage has a detrimental, albeit inconsistent, association with sprint performance. This was only measured over an acute window, though, and did not look at how intoxication may affect performance over a chronic period of time, for example, a two- or three-day hangover. Interestingly, more recent research actually shows no change in strength or power characteristics following acute alcohol ingestion.

Implications for recovery

One of the key areas to think about when it comes to exercise recovery is muscle damage and associated inflammation. This may be from training or competition – either way it’s important to consider.

As mentioned earlier, one of the main markers which have been investigated in the literature is creatine kinase (CK). At present, acute ingestion appears to have very little impact on exercise-mediated muscular damage. CK is highly variable between individuals and may not be the best marker to assess in this situation – better markers to measure are the circulating levels of pro-inflammatory cytokines. Following exercise stress, muscle damage and subsequent inflammation, cytokines are released into the circulation in an attempt to start the muscle recovery process. The inflammatory processes appear to be influenced by both chronic and acute alcohol use – not good news if you are an athlete (or know of athletes) who consumes alcohol frequently. Essentially, routine consumption will promote high circulating levels of pro-inflammatory variables.

Practically, I think there’s a fine line between allowing an athlete to celebrate a good win, and going overboard so much that it then disrupts their recovery from exercise. When I used to work in rugby, it was a simple rule of a bottle of beer in the changing room post-match to celebrate a win.

I really like the way Luke Vella and David Cameron-Smith summarise their thoughts on alcohol, athletic performance and recovery in their 2010 paper. Essentially, they say how both the effects of alcohol on human physiology and the parameters that determine athletic performance are multifactorial and extremely complicated. The literature shows there are many adverse symptoms caused by acute alcohol ingestion. However, the notion that alcohol consumption affects performance has not received enough consistent validation to advance beyond being anecdotal.

Nevertheless, just because the negative influences of alcohol on performance are not well understood, it does not mean that its use prior to, or following, competition is recommended! Something that is pretty interesting to know is the current data demonstrates a severe lack of analysis on the possible detrimental action of alcohol in the recovering athlete. So basically, although as practitioners we know that we shouldn’t really be advising athletes to consume alcohol, we actually don’t know the full effects of it on recovery.

One thing we can be sure of is the available evidence in both cellular and rodent-models. Based on this literature, we can be confident that athletes should remain wary of ingesting alcohol following intense exercise, focusing instead on effective dietary strategies proven to enhance recovery.

My shout…

In regards to dietary strategies for the athlete, it is amazing how many players I have spoken to about the “hidden” calories in alcohol. For example, a rum and coke (185kcal), craft beer (350kcal) and a Pina colada (526kcal) can all be very easily consumed, without consideration for the actual calorie content of each drink. From my experience, many athletes have no problem meeting up with their friends to sink three or four pints (around 1000kcal). Surprising, right? But, when four or five chocolate bars (the name of which is a planet and rhymes with cars) are put in front of them and they’re told to eat them all, they question the instruction and generally mention that it is unhealthy and will not help with their body composition goals. What’s funny about this is that they both have roughly the same calorie content.

My point here is, it is important to understand that calories are also in liquid beverages just as much as they are in food! So, next time you’re out on the town, think about your drinks as multiple chocolate bars and consider how it might affect your energy balance.

…and one for the road

Ps. here is a nice infographic which summarises this blog well.

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Dr. James Morehen

Dr. James Morehen is the Lead Performance Nutritionist for England Rugby and previously also worked as the Performance Nutritionist for Bristol Bears Rugby Union. He is a SENr registered performance nutritionist and works privately with both elite athletes and individuals through his business Morehen Performance Ltd.

More content by James

The post Alcohol and performance: How should athletes approach it? appeared first on Science for Sport.

The ketogenic diet consists of a high fat, adequate protein, and low carbohydrate intake but limited research has been conducted on the impact of this diet in team sport athletes.

By Dr. James Morehen
Last updated: March 3rd, 2023
5 min read

Original study

Antonio Paoli, A., Mancin, L., Caprio, M. et al. Effects of 30 days of ketogenic diet on body composition, muscle strength, muscle area, metabolism, and performance in semi-professional soccer players. J Int Soc Sports Nutr 18, 62 (2021). https://doi.org/10.1186/s12970-021-00459-9. PMID: 34530857
Click here for abstract

OBJECTIVE

The ketogenic diet consists of a high fat, adequate protein, and low carbohydrate intake (<5% of total daily energy intake). Very low intakes of carbohydrates (normally <50g) lead to physiological ketosis in the body. In this process, ketone bodies are released from the liver from the breakdown of fats and converted to acetyl-CoA, which enters the Krebs cycle and is oxidised for energy.

The ketogenic diet has been considered a possible alternative to extreme caloric restriction to tackle increases in body fat by athletes in the off-season. However, research on the ketogenic diet is conflicting. Certain studies report negative effects on performance following the ketogenic diet, whilst others suggest a positive effect, or no difference compared to ‘western’ diets. However, limited research has been conducted on the impact of the ketogenic diet in team sport athletes.

This study investigated the effects of 30 days of a ketogenic diet on body composition, muscle strength, muscle area, metabolism, and performance in semi-professional soccer players.

WHAT THEY DID

Sixteen semi-professional male soccer players participated in this randomised, parallel arm, controlled, prospective study. Participants were randomly assigned to consume a very low carbohydrate ketogenic diet or a western diet for 30 days.

Athletes assigned to the ketogenic diet were provided with nutritional counselling and resources that encouraged the consumption of beef, veal, poultry, fish, raw and cooked vegetables without restriction: protein 1.8g.kg.d-1; carbohydrate: <30g.d-1; fat: 65-70% of total calories. The western diet was composed to ensure constant energy and macronutrient balance: protein: 1.8g.kg.d-1; carbohydrate: 50-55% of total calories; fat: 20-25% of total calories.

Training was strictly controlled so that all participants conducted the same level of physical activity (eight hours per week).

Participants were tested on three different days in the week before and after 30 days of dietary intervention. On day one of testing, participants’ respiratory exchange ratio, resting energy expenditure, body composition using dual-energy X-ray absorptiometry and cross-sectional area of the quadriceps were measured. Following one day of rest, participants performed a counter movement jump test. Following two more days of rest, participants completed a yo-yo intermittent recovery test level 1. Maximal voluntary isometric contraction (strength) of the right quadricep was also assessed.

WHAT THEY FOUND

Total calorie intake was reduced in the ketogenic diet (KD) group (-16%) and western diet (WD) group (-18%), with no significant difference between groups.

Changes in body fat (KD: -1.55kg; WD: -0.92kg), visceral adipose tissue (KD: -63g; WD: -27g), waist circumference (KD: -4.19cm; WD: -1.38cm) and extracellular water (KD: -3.43%; WD: 0.03%) were significantly greater in the ketogenic group than in the western diet group.

Lean tissue mass, quadricep muscle area, maximum strength and resting energy expenditure showed no changes in either group.

Respiratory exchange ratio decreased significantly in the ketogenic group, but no significant changes were observed in the western diet group (KD: -14.18%; WD: -2.85%).

Both groups improved significantly in the Yo-Yo intermittent test (KD: +28.04%; WD: +44.6%2) and countermovement jump (KD: +8.52%; WD: +3.60%), with no significant difference between groups.

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PRACTICAL TAKEAWAYS

JAMES MOREHEN’S COMMENTS

“Adherence plays a central role in the success of athletes following a ketogenic diet. I would question whether eliminating or heavily restricting carbohydrates from the diet is necessary, since safe body composition manipulation can be achieved through a western diet.

“Until more research has been conducted on the ketogenic diet for team sports athletes, practitioners should turn their attention to educating players on strategies to manipulate their current diets to optimise fat loss during the off-season. For example, periodising carbohydrates to fuel for the demands of training, focusing on low-glycaemic foods and increasing protein intake are targets that athletes can adhere to and may be more relevant than a strict ketogenic diet.”

Want to learn more?
Then check these out…

Read this article
Read this article
Listen to this podcast
Watch this video

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Every coach understands the importance of staying up-to-date with the latest sports performance research like this, but none have the time, energy, or even enjoys spending hours upon hours searching through PubMed and other academic journals. Instead, your precious time is better-spent coaching, programming, and managing all the other more important aspects of your job.

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This comprehensive topic base ensures you’re constantly expanding your knowledge and accelerating your career as quickly as humanly possible. The reviews are also hyper-focused, 1-page summaries, meaning there’s no jargon or wasted time. We cut right to the chase and tell you what you need to know so you can get back to coaching.

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Dr. James Morehen

Dr. James Morehen is the Lead Performance Nutritionist for England Rugby and previously also worked as the Performance Nutritionist for Bristol Bears Rugby Union. He is a SENr registered performance nutritionist and works privately with both elite athletes and individuals through his business Morehen Performance Ltd.

More content by James

The post Could the ketogenic diet be beneficial for team sport athletes? appeared first on Science for Sport.

• ACL rehabilitation: The pain and the background
• Why do ACL injuries occur so often?
• The power of positivity during ACL rehabilitation
• ACL rehab: Phase 1, pre-surgery
• ACL rehab: Phase 2, post-surgery
• ACL rehab: Phase 3, home time, and the first 4-6 weeks
• The secret of prepped meals
• ACL rehab, Phase 4: Progression and return to exercise
• Some final food for thought

ACL rehabilitation: The pain and the background

I can still remember the time I ruptured my own anterior cruciate ligament (ACL) in graphic clarity – hearing a sound similar to a gun exploding, feeling a wave of pain coursing through my entire body, and knowing that I faced a lengthy recovery … all those feelings are still vivid two years later. And it’s no surprise – tearing your ACL is one of the worst injuries an athlete can suffer. If you work in sport or with athletes, you will either have witnessed an ACL blowing or know someone who has experienced it – the pain on the person’s face can be unbearable to watch!

The ACL is one of the key ligaments in your knee and is pretty important to help stabilise your knee joint. Put simply, rupturing your ACL is something you would really prefer not to experience.

But ACL injuries are quite common in sport and occur in all levels of play. They are most commonly seen in sports that involve sudden stops, changes of direction, jumping and landing – like football, rugby, basketball, and American football. Previous studies have shown ACL injuries to occur at a rate of 6.5 per 100 ,000 athlete exposures (any time an athlete engages in sporting activity). This might not seem like a lot, but athlete exposures within a single team can add up pretty quickly when you consider how many players there are and how many training sessions and games they participate in.

Unfortunately for female athletes, ACL injuries occur more regularly than men. Each year 20,000-80,000 female high school athletes sustain an ACL injury. In women’s domestic football, the knee is generally the most commonly injured body part, accounting for approximately 22% of all injuries. It’s been reported females are also eight times more likely to suffer an ACL injury than males – a pretty crazy statistic right? This is believed to be as a result of a number of anatomical, hormonal, and neuromuscular differences present in females.

Why do ACL injuries occur so often?

The ACL is clearly a problematic area within the sport and athletic circles, so it’s important to ask the question: Why do ACL injuries occur so often? The British Journal of Sports Medicine released a brilliant top five most played podcast series on this topic to try to explain and understand this in detail. In brief, a sudden twisting change of motion and high-force contact can cause the ligament in the knee to over-stretch, tear, and in some cases rupture completely. A good way to explain this in simple terms is to think of an elastic band. If you pull an elastic band in either direction or twist it with a little bit of force, then it will be okay. It will return to its baseline state of being a relaxed elastic band. However, if you overstretch or pull the elastic band in either direction with excessive force, then you may start to see small tears begin to appear. This tearing is very similar to what happens with the ligaments in the knee. Overstretching or pulling is not something these ligaments like, hence why tears appear – almost as a warning not to overdo it. However, in some cases, the force applied to the elastic band can be so strong and sudden that it completely snaps. The band can’t handle the force, and BOOM, it snaps away in your hand. This is the sound resembling the gunshot I referenced earlier.

Within the knee, it is the ligament that completely ruptures and shifts away from its stable starting position. I think you will agree, this does not sound enjoyable. Professor Keith Baar has to be one of the best researchers in this area and explains the injury mechanism well in these two videos here and here.

For many athletes, this injury signals the start of a lengthy recovery period of either rehabilitation without having surgery or, in most cases, preparing to go under the knife before beginning the rehabilitation process. Either way, it’s an interesting road ahead. To hear what a professional rugby player has made of it all, please read this article where England Rugby star Jack Willis speaks openly about his recovery from knee surgery.

The power of positivity during ACL rehabilitation

All is not doom and gloom, though, and it is important to remain positive during ACL rehabilitation. The recovery process is actually a great time to build resilience, character, and reflect on areas you can improve on once you are fully fit again.

The reason I know this is because I have experienced it myself. I won’t bore you with the details of how I sustained it, but I ruptured my ACL and suffered a significant tear in my meniscus a little while ago and can confirm it was quite painful and swollen! Funnily enough, it took me 10 months to realise I had sustained the injury, and in fact, carried on with my regular strength-based training, running 10km and even enjoyed skiing and snowboarding. Many athletes also continue with controlled and prescribed training before having surgery to repair their knee – the difference is, unlike me, they are generally aware of their injury!

As a performance nutritionist, I wanted to use myself as a mini project for a personal ACL and meniscus recovery case study. I re-read the key literature, listened to countless podcasts, and then applied the evidence and literature to my own personal nutritional strategies to recover from my surgery. Below I will link you to these key resources and explain how I did it.

ACL rehab: Phase 1, pre-surgery

Once I knew my surgery date, I had about four weeks to prepare myself before the surgeon worked their magic. I used this time wisely to reduce my fat mass slightly (increased cardio in the early mornings) and increase muscle mass on both legs. I followed a classic hypertrophy program for back squats and Romanian deadlifts and maintained a solid level of running. Additionally, I followed a high protein (2.5g/kg body mass) moderate carbohydrate (2-3g/kg body mass) nutritional strategy, consuming carbohydrates during and around training and reducing carbohydrate intake in the evening – essentially, fuelling for the work required. I also consumed creatine prior to surgery to support muscle mass growth.

In the final few days before surgery, I increased my creatine intake to 20 g per day for seven days to significantly increase my muscle creatine stores. I did this to try and minimise any muscle wastage that would occur once I had the operation. This was then reduced to 5 g per day post-surgery as a maintenance dose. I also prepared my surgery ‘care package’ before hitting the operating table. This care package contained food and supplements that I took into the hospital with me, ready for when I woke up from the operation (see below).

This care package included:

• Protein bars
• Collagen protein shots
• High omega-3 fish oil and protein drink
• Multivitamins, probiotics, omega-3 tablets
• Chewable vitamin C tablets

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ACL rehab: Phase 2, post-surgery

Although hospital care nowadays is generally very good, I didn’t want to rely on the food provision at the clinic just in case it wasn’t quite as good as I needed it to be. Both the protein bar and repair shot provided me with a good quality source of both whey (~ 20 g) and collagen (~ 15 g) protein. You may think I am mad, but as soon as I woke from the operation, I consumed both supplements to begin the recovery and repair process. Alongside the protein, I swallowed the multivitamin, probiotic, omega-3 and vitamin C tablets. I think my nurse thought I had some kind of problem with the amount of supplements pills I had with me!

Although I habitually eat healthily in terms of lots of fruit and vegetables and try to achieve a rainbow a day of colours, I wanted to supply my body with a good multivitamin to support immune health, having just woken from surgery. The probiotic was to look after my gut, the omega-3 was to help reduce swelling and the vitamin C the same – to act as an antioxidant and reduce soreness and inflammation. I continued to take all four of these for the next six months. Another excellent product I consumed in the first few hours of waking up was an omega-3-enriched protein drink. Once again, this provided me with a good quality source of protein and 1.4 g of quality fish oil to help reduce the inflammation that surrounded my knee and upper thigh.

ACL rehab: Phase 3, home time, and the first 4-6 weeks

There is a lot to be said here about getting into a good routine and sticking to it. Once I was home, I set out a regimented plan of attack regarding specific feeding times and supplement schedules to help reduce the swelling as quickly as possible from a nutritional point of view.

Having previously had many Dual X-ray Absorptiometry (DEXA – body composition assessment) scans as a student, I had access to data which would help me build an individualised nutrition strategy regarding total energy and macronutrient (carbohydrate, fat and protein) intake.

I used the commonly cited Cunningham equation ((lean body mass x 22) + 500) to work out my predicted resting metabolic rate (RMR). However, if you do not know your lean body mass or have access to finding it out, then you can use the following equation:

RMR (kcal.day-1) = 1254 + (9.5 x body mass in kg).

In simple terms, this equation is working out how many calories you normally burn in a 24-hour window. It does this by multiplying 9.5 x your body weight + 1254. so for me this would be 9.5 x 73kg = 693.5, then add 1254, so 693.5 + 1254 = 1947.5. Therefore my RMR is approx. 1947 calories per day.

My RMR is the total amount of calories I would need to maintain normal physiological function in a rested state. For me, this is around 1900-2000 kcal per day. However, considering my body had just come out of an operation, I knew it was going to take more calories than my RMR suggested, to support the fact my body was working overtime to recover, repair, and rebuild the soft tissue around the knee.

This is brilliantly shown in a case study on an English Premier League football player who, following an ACL operation, had a similar total energy expenditure to non-injured, fully active football players. The authors of this study said this similarity was due to the injured player working overtime to help repair and recover his body – pretty cool, huh?

It was therefore important I provided my body with ample calories from good-quality sources of nutrition rather than poor ones. For example, lots of fresh protein (i.e., oily fish, lean white meats, etc.), fruits, and vegetables, rather than sugary, fatty and pro-inflammatory foods.

The increase in calories mainly came from protein, as I tried to maintain a total intake of around 3 g per kg of body weight (approx. 210 g). When I was awake, I maintained protein distribution throughout the day to every 2-3 hours (i.e., 20-30 g of protein, consumed every 2-3 hours), in line with key literature. You may laugh, but for the first few days, I set my alarm for every three hours to remind me to down my next source of protein. After a few days, my internal alarm was set, and I had formed a habit that had stuck well. This habit-forming was born from inspiration from reading Atomic Habits by James Clear – a brilliant book, and I would highly recommend it to anyone reading this blog.

Another supplement I added was vitamin D3. As I had my operation in October (Autumn time in the UK), and I was pretty much immobile, so my access to daily sunlight was limited. I had a good guess I was not going to see much sunlight for a few weeks, and even if I did, the sun was not going to be strong enough to give me a natural dose of vitamin D3. That’s why I opted for the supplement throughout the winter months and took one tablet per day for the next six months.

The secret of prepped meals

Now, anyone who has been on crutches for a period knows how difficult it is to get around the house. More specifically, how hard it is to try and cook in the kitchen whilst hobbling around like Captain Jack Sparrow after one too many rums. I didn’t want to put myself through this struggle, so I decided to invest in a prepped meal company to make it easier for me. I was able to pick specific meals out and if I needed to adjust the macronutrients of each meal, it was as easy as customising my order. Investing in pre-made meals really was a great choice – all I had to do was put them in the microwave for two minutes, and I knew I had a good-quality meal ready to go.

Before we move on, I just wanted to summarise and share in brief my rough nutritional intake day to day. Please see below:

Breakfast

3 eggs with peppers and onion
1 slice of rye bread
1 repair shot
1 Whey protein with creatine and glutamine
1 multivitamin
1 omega 3
1 probiotic
1 vitamin D3

Snack

1 Greek Yoghurt with mixed berries
1 Whey shake

Lunch
1 Prepped meal – 30 g of lean chicken, 40 g of brown rice and fresh vegetables
1 repair shot

Snack

1 Enhance Recovery sports drink
1 piece of whole fruit

Dinner

1 Prepped meal – 30 g of lean turkey, 40 g of brown pasta and fresh vegetables
Pre-bed
1 repair shot
1 Whey protein with creatine and glutamine

ACL rehab, Phase 4: Progression and return to exercise

Following the first few weeks, my knee was feeling great and I was progressing well with exercises. My timeline was pretty much what you would expect for an ACL recovery and meniscus repair (i.e., 1-4 weeks reducing inflammation, 4-8 weeks beginning mobility and light exercise).

I continued with the nutritional strategy outlined above, and on days when my exercise increased, I slightly increased the fuel I consumed too. To be honest, there wasn’t really a period where I shied away from nutritional intake, which I have seen in some athletes. It is not uncommon to hear athletes “not eating enough” or quickly losing weight because they are undereating. I was actually the opposite – I was purposely overeating but with good-quality calories.

My physiotherapist was happy with my progress, and at 13 weeks post-operation, I ran 5km in 26 minutes which is a pretty great time considering what I had been through (a good 5km time is anywhere near 25 minutes). This was a brilliant day – a day where I genuinely felt proud of myself for sticking to a good routine with nutrition. Importantly, this wasn’t just nutrition off the cuff – I was reading the literature and applying it to myself to prove that it works. It is possible –  you can return to exercise in a considerably quick time post-op with the help of nutrition.

Since that day, I have run every week and resumed all my strength training again.

Some final food for thought

Although suffering an ACL injury is harsh for any athlete, it doesn’t have to be a negative experience. I found myself really enjoying the different stages of rehab and experiencing first-hand how important nutrition can be to nail a quick return to exercise. I did not have access to a physio every day as a professional athlete would, but one thing I did have access to was a good-quality nutritional strategy.

I was convinced reading the correct literature and applying it to myself would result in a strong outcome for the project. It made me think about how many athletes who suffer an injury potentially switch off and become demotivated as a result. How many of them think “ah, screw it” and turn to sweets, chocolate, and fast food as a way of comforting themselves for a few days.

I can confidently say I hit 90-95 % of my nutritional strategy consistently day to day. I didn’t consume fast food or snacks, which were going to promote inflammation and delay recovery. Of course, I had the odd low-calorie ice cream or sweet, but really stayed committed to keeping it focused throughout. If you are going to snack on something a little naughty, just make sure it is not a daily occurrence!

My advice for anybody who has either suffered an ACL injury or is about to go into surgery for another soft tissue injury would be to sit down with a registered nutritionist or dietician and work on a bespoke nutritional strategy that is both achievable and enjoyable for you to follow. Although you may not think nutrition plays a pivotal role in the recovery from surgery, I can tell you first-hand that the reason I am running a half-marathon 10 months post-operation is due to a solid evidence-based nutrition strategy.

The post ACL rehabilitation: How a strong nutrition plan can help you recover faster appeared first on Science for Sport.

Your weekly research review

By Dr. James Morehen
Last updated: March 3rd, 2023
1 min read

Photo credit: Tropical Bloom Ltd

Original study

Lachenmeier, D.W.; Diel, P. A Warning against the Negligent Use of Cannabidiol in Professional and Amateur Athletes. Sports 2019, 7, 251.

Click here for abstract

Background & Objective

In 2019, Cannabidiol (CBD) was probably one of the most talked about products within the health, sport, and medicine settings (listen to a related discussion with the podcast below). Widely claimed effects of decreased anxiety, fear, memory extension, and anti-inflammatory properties have resulted in many professional athletes taking this cannabinoid and even some beginning their own companies.

This brief commentary presents a clear and robust warning to both professional and amateur athletes against the use of such products.

What They Did

The authors introduce this commentary by highlighting the fact that cannabis is illegal in many jurisdictions and has also been included on the World Anti-Doping Agency (WADA) list as a substance prohibited in-competition.

Although there are claims of cannabis being helpful for extreme sports (e.g. rock climbing, freestyle skiing, skydiving), as it may improve muscle relaxation and reduce anxiety, there are only a few studies regarding its effectiveness, with previous reviews concluding there is a lack of evidence regarding performance-enhancing effects.

Clearly smoking cannabis is not advisable, but more recently the interest lies with CBD, which is one of the cannabinoid compounds naturally found in Cannabis sativa.

What They Found

CBD is structurally related to the main psychoactive compound tetrahydrocannabinol (THC), which is responsible for the adverse effects of cannabis. Although nonpsychoactive, it may be responsible for some advantageous effects, including anti-inflammatory properties, relief of arthritis, and pain-related behaviours, as well as postexercise recovery. Most of the CBD products worldwide are available as food supplements or compounded foods, with CBD or hemp extract as an ingredient. Such unapproved products normally do not comply with quality standards.

The WADA has excluded CBD from its list of prohibited cannabinoids, however, it is important to note that according to the 2020 WADA prohibited list, cannabinoids in general are still listed in group S8 – substances forbidden to be used in competition. Importantly, most CBD products are sold as so-called full-spectrum products, meaning they also contain other cannabinoids. As such, the use of full-spectrum CBD products is definitely prohibited by WADA.

Studies have detected residual levels of THC in CBD products with 10 out of 28 commercial CBD products from the internet and retail market, and more than a third of all the available products would probably lead to a false positive urine doping test.

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Practical Takeaways

⇒ The CBD market is a highly unregulated and uncontrolled market currently, making it a minefield for any athlete. The easy answer is to simply not purchase.

⇒ Should your athletes choose to consume this substance, it is wise to know that the threshold for a positive THC test has been set by WADA to 150 µg.mL-1 of 11-nor-9-carboxy-THC in urine.

⇒ Many studies of CBD products have detected considerable mislabeling of content, resulting in athletes not really knowing what they are purchasing. If an athlete wishes to purchase a CBD product, they must ask the producer to provide credible analytical proof for the claims about CBD content on the labels.

⇒ Health Span Elite have recently released Levagen + Sport, a tested product that has similar effects to CBD.

Reviewer’s Comments

“CBD received a lot of attention last year and this looks set to continue into 2020, with products now containing CBD as a drink (see video below). Although CBD itself is not banned, it’s the actual content of the commercial products that often contain banned substances, such as THC and other unregulated cannabinoids. For me, this risk alone should deter athletes and also be enough of a point for practitioners to raise with athletes who are considering trying it.

If athletes are seeking assistance with things like sleep, recovery, anxiety, soreness, and inflammation, I believe there are many other proven strategies that would help or improve each area for the athlete. For example, if your athlete is sitting on their phone in bed, this maybe the reason they are struggling with sleep. Advise would be to work on their current sleep hygiene practices. Likewise, if they are struggling with soreness, are they eating enough of the correct nutrients to help muscles recover and repair? Advise would be to increase protein intake and antioxidants.”

Want to learn more?
Then check these out…

Watch this video
Listen to this podcast
Read this infographic

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Want more research reviews like this?

Every coach understands the importance of staying up-to-date with the latest sports performance research like this, but none have the time, energy, or even enjoys spending hours upon hours searching through PubMed and other academic journals. Instead, your precious time is better-spent coaching, programming, and managing all the other more important aspects of your job.

The solution…

The Performance Digest
The Performance Digest is a monthly summary of the latest sports performance research reviewed by our team of hand-selected experts. We sift through the 1,000+ studies published in the realms of sports performance every, single month and review only those which are important to you. Each monthly issues contains 19 research reviews in all of the following disciplines:

This comprehensive topic base ensures you’re constantly expanding your knowledge and accelerating your career as quickly as humanly possible. The reviews are also hyper-focused, 1-page summaries, meaning there’s no jargon or wasted time. We cut right to the chase and tell you what you need to know so you can get back to coaching.

Join the thousands of other coaches who read it every, single month. Click here to get instant access for free…

Dr. James Morehen

Dr. James Morehen is the Lead Performance Nutritionist for England Rugby and previously also worked as the Performance Nutritionist for Bristol Bears Rugby Union. He is a SENr registered performance nutritionist and works privately with both elite athletes and individuals through his business Morehen Performance Ltd.

More content by James

The post Cannabidiol use in professional sport: is it really worth the risk? appeared first on Science for Sport.

Your weekly research review

By Dr. James Morehen
Last updated: March 3rd, 2023
4 min read

Original study

Jovanov, P., Đorđić, V., Obradović, B., Barak, O., Pezo, L., Marić, A., & Sakač, M. (2019). Prevalence, knowledge and attitudes towards using sports supplements among young athletes. Journal of the International Society of Sports Nutrition, 16(1), 27.

Click here for abstract

Background & Objective

Worldwide, most professional athletes use sports supplements either during training and/or performance. With this, many young athletes (15-18 yr) who aspire to be professionals, also now take supplements, but do they really know why they are taking them?
Considering this is one of the fastest growing industries in food and beverage, with many companies paying athletes and offering sponsorship deals for young athletes, the authors of this study wanted to:

1. Determine the prevalence of sports supplements.
2. Determine the source of information regarding supplementation.
3. Assess beliefs and attitudes towards the use of supplements.
4. Estimate the level of knowledge with specifically defined survey questions and the reasons for taking supplements.
5. Identify trends or differences between categories of supplement users.
6. Obtain an insight into young athletes ethical dilemma about the misuse of sports supplements.

What They Did

The survey was conducted between March and November 2018, with the inclusion criteria of athletes being aged 15-18 yr and who have competed at international level. In total 348 athletes from Serbia (39.4%), Germany (23.0%), Japan (20.1%), and Croatia (17.5%) took part in the survey representing 18 different sports. The survey included twenty questions which were split into four parts:
⇒ Simple demographic and personal information.

⇒ Information regarding the usage, importance, source of information, safety, and procurement of sports supplements.

⇒ Test the athletes knowledge about the correct timing, dosage, and reason for use of each sports supplements
⇒ Investigation of athletes’ beliefs and attitudes towards the use of sport supplements and possible anti-doping rules violations.

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What They Found

The survey showed 82.2% of athletes used supplements, of which 60.6% were male. 82.2% of athletes used one-two different supplements at the same time, 62.1% two-three, 35.9% three-four, and 14.7% used four and more supplements, with kayak, swimming, and karate identified as the sports with the highest number.

Whey protein was the most popular supplement, with 54.5% consuming it among ten other supplements. Unfortunately, young athletes appear to lack proper knowledge about the use of creatine (11.1% of athletes responded correctly), beta alanine (20.0%), amino acids (20.0%), nitrate oxide (22.2%), glutamine (37.5%), protein (38.5%), and carbohydrates (48.3%). Yet they seem to have more knowledge about sports drinks (50%), caffeine (61.8%), and vitamins and minerals (71.0%).

The main reasons athletes wanted to take supplements was for an improvement in performance (35.3%), with 72.1% of athletes being aware of a certain health risk, 14.9% thought they were risky, and 12.9% of athletes considering them to be safe. Additionally, the coach appeared to be the main source of information regarding the use of creatine, carbohydrates, amino acids, caffeine, sports drinks, glutamine, nitrite oxide, protein, beta alanine, vitamins, and minerals.

Finally, this study revealed that 55.5% of athletes had access and were familiar with the regulations of the World Anti-Doping Agency (WADA).

Practical Takeaways

⇒ Protein supplements are widespread among young athletes, and so education around the correct timing type and total amount should be provided to athletes.

⇒ The coach seems to be the main source of information about supplementation practices and, therefore, highlights the importance of us as practitioners knowing the right information
⇒ The enhancement of athletic performance is the main reason young athletes use supplements.

⇒ Young athletes show inadequate level of knowledge about the proper and intended use of sports supplements, thus highlighting how important it is to implement education strategies for our athletes.

⇒ Ongoing education to all coaches and athletes about sports supplements is necessary for improving performance and minimising the risk of positive doping results. This will result in a much safer environment when athletes take supplements.

⇒ Insufficient knowledge causes ethical dilemma about the misuse of sports supplements.

Reviewer’s Comments

“Although this study utilised a survey, rather than implementing an intervention or mechanistic procedure, I really like it as it highlights some very important points for practitioners working with young athletes. Whether you like it or not, young athletes are taking supplements (which is discussed in the podcast below), and worryingly with not many of them knowing the complete reason why or how to take them properly.

In my own practice, I try to follow a – where possible – food first approach with all the athletes I work with, but inevitably with time constraints, world-wide travel, and ease of access, the results of this study have once again highlighted to me how important it is to educate those that will probably end up taking them anyway. In particular, it appears that the younger the athlete is, the more likely they are to listen to the guidance of the coach, which therefore underlines how important it is for us, as coaches, to know why and how to take each supplement. Follow the International Olympic Committee decision tree info-graphic for guidance (see below).

Finally, although this study was only performed across four countries and not in the UK, I do think we would see similar results in the UK to that which has previously been shown in UK junior national track and field athletes in the article below.”

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Want to learn more?
Then check these out…

Read this article
Read this infographic
Listen to this podcast

Dr. James Morehen

Dr. James Morehen is the Lead Performance Nutritionist for England Rugby and previously also worked as the Performance Nutritionist for Bristol Bears Rugby Union. He is a SENr registered performance nutritionist and works privately with both elite athletes and individuals through his business Morehen Performance Ltd.

More content by James

The post Do your athletes know why they are taking supplements? appeared first on Science for Sport.

Your weekly research review

By Dr. James Morehen
Last updated: March 3rd, 2023
5 min read

Background & Objective

Heavy exercise from training and competition combined with life stress such as travelling, emotional status, and pressures to succeed can all have an effect on the innate and acquired immunity in athletes. In this review article, Neil Walsh provides new insights and evidence-based recommendations for coping with the various challenges that athletes encounter on immune health, including: heavy exercise, life stress, sleep disruption, environmental extremes, and nutritional deficits.

What They Did

Neil provides the background and overview of stress-immune interactions, identifying particular key factors that can lower immunity in athletes. Importantly, the common pathways for the immune response to physical and psychological challenges are highlighted, which result in the release of Catecholomines and Glucocorticoids. The innate, mucosal, and acquired immunity are overviewed with both counts and functional aspects related to the influence of prolonged exercise (>90 min); which is a duration many athletes will be exposed to in either training or competition. Additionally, Neil displays values of particular nutritional supplements for reducing the common ‘cold’ and maintaining immunity in various scenarios.

What They Found

In a simple and clear manner, Neil provides some succinct recommendations in relation to how athletes and support practitioners can modify training and recovery activities, optimise psychological well-being, improve sleep strategies, mitigate negative outcomes from those encountering extreme environments, and lastly, how nutritional aids can maintain health in athletes.

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Practical Takeaways

Modifying training and recovery activities to maintain immune health in athletes
Manipulate training volume and/or intensity to manage training load; keep the size of increments in volume and intensity to 5–10% per week (particularly during winter); increase the frequency of shorter, so-called “spike” training sessions, rather than enduring fewer but longer sessions; implement recovery activities immediately after the most intensive training sessions; undertake easy-moderate training sessions after each high-intensity session; plan an easier recovery/adaptation week every second or third week of the training cycle; permit athletes at heightened risk of illness several weeks of active recovery after the completion of a season or major competition.

Optimise psychological well-being and maintain immune health in athletes
Keep unnecessary life stress to a minimum; monitor and manage all forms of stress (psychosocial and physical); monitor life demands (e.g. using the DALDA questionnaire); monitor mood, stress, and anxiety; implement stress management interventions where necessary.

Sleep recommendations to maintain immune health in athletes
Aim for 7+ hours of sleep each night; avoid restricting sleep over many days and “catching-up”; monitor morning freshness and vigour; consider monitoring sleep duration and efficiency using a wearable device; daytime naps may be beneficial; optimise sleep hygiene routine in the hour before bedtime (e.g. reduce psychological strain, go “screen-free”, and ensure darkness at bedtime: see attached infographic).

Maintain immune health in athletes encountering extreme environments
Carefully manage training load and recovery when training with additional heat and/ or hypoxia; acclimation to heat and/or hypoxia may limit the influence of environmental extremes on immune health; take extra precautions to avoid prolonged periods of breathing large volumes of cold, dry air (e.g. when training and competing in the winter); personal hygiene, sleep hygiene, proper nutrition, and reducing unnecessary stress become increasingly important during long-haul travel to training camps and competition; short-lasting exposure to environmental extremes may enhance immunity and reduce sickness (e.g. 30-secs hot-to-cold showers).

Nutritional recommendations to maintain immune health in athletes
Match energy intake to expenditure; avoid crash dieting; eat a well-balanced diet; consume >50% daily energy intake as carbohydrate; ensure adequate protein intake (1.2−1.6 g/kg body mass/day); consider 1000 IU/day vitamin D3 from autumn to spring to maintain sufficiency; at the onset of a cold, take zinc acetate lozenges (75 mg/day); consider probiotics (≥1010 live bacteria/day) for illness prone/travelling athlete.

Reviewer’s Comments

“Irrespective of athlete’s playing level, this review touches on many areas that can affect training, competition, and ultimately, the health in those partaking in heavy training periods and competitions. It is important to consider that recommendations should be applied on an individual basis rather than a blanket approach. Indeed, many of them will hold true and important with most athletes, but maybe the biggest wins would come from understanding which areas your athletes already do very well, and therefore, which areas need the most work on to gain the biggest improvements. Lastly, it is important to remember that any supplement being purchased should be from a company that can provide the ‘batch certificate’ with it; this ensures the products/ supplements are clean and contain no WADA banned substances.”

Want to learn more?
Then check these out…

Watch this video
Read this article
Listen to this podcast
Read this infographic

The full study can be read here.

Want more research reviews like this?

Every coach understands the importance of staying up-to-date with the latest sports performance research like this, but none have the time, energy, or even enjoys spending hours upon hours searching through PubMed and other academic journals. Instead, your precious time is better-spent coaching, programming, and managing all the other more important aspects of your job.

The solution…

The Performance Digest
The Performance Digest is a monthly summary of the latest sports performance research reviewed by our team of hand-selected experts. We sift through the 1,000+ studies published in the realms of sports performance every, single month and review only those which are important to you. Each monthly issues contains 19 research reviews in all of the following disciplines:

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Dr. James Morehen

Dr. James Morehen is the Lead Performance Nutritionist for England Rugby and previously also worked as the Performance Nutritionist for Bristol Bears Rugby Union. He is a SENr registered performance nutritionist and works privately with both elite athletes and individuals through his business Morehen Performance Ltd.

More content by James

The post How to maintain immune health and prevent illness in athletes appeared first on Science for Sport.

Your weekly research review

By Dr. James Morehen
Last updated: July 1st, 2023
4 min read

Background & Objective

Weight making-sports require athletes to reach a certain body mass on a scale before they can qualify to then compete in the respective weight category. The pressure to reach certain weights to gain a competitive advantage over opponents is reaching new extremes, so much so that certain weight-making strategies are resulting in athlete deaths and is discussed by one of the authors of this case study in the podcast below.

With this in mind, the weight-making research group at Liverpool John Moores University aimed to describe the strategies of an individual male athlete as he made weight before competition and quantify the physiological and metabolic impact of the extreme weight cut.

What They Did

The athlete presented was a 22-year-old professional male MMA fighter, with the contest under investigation for the case study being the defence of his featherweight championship. At the beginning of the camp, he weighed 80.2 kg and was required to make weight at 65.7 kg over an 8-week period.

They assessed the athlete at regular periods before and after the contest for body composition using dual energy X-ray absorptiometry (DEXA) and skinfolds, resting metabolic rate, and peak oxygen uptake with blood samples taken and analysed at a local hospital.

The protocol of the 8-week weight-making period included the following phases:

1) 7-week energy restriction period.

2) 6-day water loading period.

3) An acute weight-cut strategy.

4) Rehydration and refuel strategy

5) Ad libitum recovery period following the fight.

What They Found

During phase 1, the athlete lost 4.4 kg. During the “cut”, the athlete exhibited clear symptoms of the relative energy deficiency in sport syndrome, reductions in resting metabolic rate, the inability to complete the maximal oxygen uptake test and perturbations to endocrine status and hypercholesterolemia (high cholesterol).

In phase 3 during the cut to make weight (weight loss of 7.3 kg), the athlete experienced a significant stress response:

⇒ 3-fold increase in plasma cortisol
⇒ Evaluations in serum proteins
⇒ Elevations in plasma osmolality
⇒ Elevations in plasma sodium concentrations

The plasma sodium observed (148 mmol.L-1) was near severe levels of hypernatremia (>150 mmol.L-1) where mortality may occur. Similarly, the relative and absolute changes in serum creatinine levels during the final phase of the weight cut are consistent with acute kidney injury.

Finally, following the 32-h rehydration and refuelling strategy, the athlete gained 10.6 kg in absolute mass and 2 weeks after the competition, resting metabolic rate, markers of endocrine status, lipid profile, hydrations status and kidney function had all returned towards normative ranges.

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Practical Takeaways

For practitioners and coaches working with athletes that are required to make weight for competition, this case study provides clear data showing the potentially harmful effects of making weight poorly (specific to this individual). The athlete showed clear signs of relative energy deficiency, evidenced by:

⇒ Reduced metabolic rate.

⇒ Inability to complete performance tests.

⇒ Alterations to endocrine hormones.

⇒ High cholesterol.

⇒ Dehydration-induced hypernatremia.

⇒ Acute kidney injury.

Although based on one individual, this case study shows the harmful (and potentially fatal) effects of extreme weight cutting in MMA athletes and represents a call for action to governing bodies to safeguard the welfare of MMA athletes. Similar habits of making weight are reported elsewhere (refer to the article below).

Practically, athletes and coaches should seek help and advice from qualified dieticians and sport nutritionists before attempting to make weight.

Reviewer’s Comments

“Personally, working with professional boxers and Olympic-level Judo athletes, I know how important it is for them to make weight safely and allow them to perform to the best of their ability. For me, the data presented by this research group is alarming and shows just how close the athlete was to potentially fatal outcomes, in particular to acute kidney damage.

Although more and more research is now being performed on these athletes who are required to make weight for competition, it worries me that the people who can control the rules and regulations of such weigh-ins are not willing to listen and thus change the rules around weight categories for the better. Will we see another fatal outcome this year like the one mentioned above?”

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Want to learn more?

Then check these out…

Read this article
Read this article
Listen to this podcast

The full study can be read here.

Dr. James Morehen

Dr. James Morehen is the Lead Performance Nutritionist for England Rugby and previously also worked as the Performance Nutritionist for Bristol Bears Rugby Union. He is a SENr registered performance nutritionist and works privately with both elite athletes and individuals through his business Morehen Performance Ltd.

More content by James

Do you work in weight category sports? Let us know how you ensure healthy weight loss below…

The post The severely detrimental effects of making weight the wrong way appeared first on Science for Sport.