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.

Beyond the well-documented health benefits of Omega-3s, they can also play an important role in muscle strength, endurance, recovery, and injury prevention for athletes.

By Brittany Johnson
Last updated: March 1st, 2024
4 min read

Omega-3s – why fats shouldn’t be feared

You’ve likely heard about Omega-3 fatty acids, but do you know why they are the talk of the town in nutrition circles? Omega-3s are groups of fatty acids (fat) found in our food and are the true ‘alphas’ of fat for performance. Why? Let’s find out …

Fat is an important macronutrient for athletes to meet calorie demands, prevent using protein for energy, and help with recovery. Fats in our food are either saturated or unsaturated based on the structure of the fatty acid – an easy rule to remember is saturated fat is found primarily in animal-based foods, with the exception of palm and coconut oil, and unsaturated fat is found primarily in plant-based foods, with the exception of fatty fish (e.g., salmon).

There are many types of unsaturated fats, but two commonly known are Omega-3 and Omega-6 fatty acids. Most people get plenty of Omega-6 in their diet but not nearly enough Omega-3. Foods rich in Omega-6 include mostly vegetable oils, commonly found in highly processed foods. Omega-3 rich foods include fatty fish, olive oil, walnuts, chia seeds, and flax seeds but they are typically inadequate in most daily diets, especially if consuming fatty fish is not part of your weekly intake.

There are three types of Omega-3 fatty acids found in food: Alpha Linolenic Acids (ALA), Eicosapentaenoic Acid (EPA), and Docosahexaenoic Acid (DHA). ALA is an essential fatty acid (meaning our bodies do not make it) but the research showing Omega-3s as the true alphas of health benefits and performance focuses on EPA and DHA. So, let’s talk about those performance benefits…

Potential benefits of Omega-3 for athletic performance

Beyond the well-documented health benefits of Omega-3s — including heart health, weight management, and blood sugar control — Omega-3s play an important role in muscle strength, endurance, recovery, and injury prevention for athletes.

OMEGA-3 FOR STRENGTH
Studies have shown Omega-3s boost muscle protein synthesis, which increases muscle mass and strength. The research suggests Omega-3s, specifically EPA, improves protein metabolism. Further, recent research demonstrates Omega-3s prevent the loss of muscle mass, meaning if you’ve sustained an injury and want to maintain muscle mass, adding Omega-3s could be a dietary tool to help maintain your body composition during healing.

Improving muscular strength requires a higher load of training and additional caloric intake to gain muscle mass, and Omega-3s contribute to this by adding daily calories to replenish your training calorie deficits. Fats contain nine calories per gram compared to four calories per gram in carbohydrates and protein. Therefore, fat is more calorically dense, allowing athletes to fuel up and meet higher caloric requirements to build muscle.

OMEGA-3 FOR ENDURANCE
Few studies have examined how Omega-3s improve endurance, however, some evidence suggests ingestion of Omega-3s can improve endurance capacity. Omega-3s act as a vasodilator, increasing oxygen flow during exercise, which increases endurance. Other studies show higher Omega-3 consumption reduces fatigue. While there are limited studies on endurance training, there is some evidence that supports Omega-3s’ potential for improving endurance.

OMEGA-3 FOR RECOVERY
Omega-3s contain anti-inflammatory properties which aid in muscle recovery and injury prevention. Consuming higher Omega-3s improves the integrity of your cells and cellular function, ultimately reducing muscular damage. Just seven days of supplementation can decrease post-exercise muscle damage and soreness.  Additionally, Omega-3s have been shown to improve sleep, which is a vital piece of the puzzle for performance recovery .

In conclusion, it appears Omega-3s can help athletic performance by improving muscle strength, endurance, and reducing recovery time.

Omega-3 rich foods to include in your diet

ALA is found in plant-based nuts, seeds, and oils. EPA and DHA are found in fatty fish and marine algae. Therefore, it’s recommended to consume two servings per week of low-mercury fatty fish such as salmon, sardines or herring to meet 500mg per day of EPA and DHA. Generally, smaller fish have lower mercury content than larger fish, and wild fish have more Omega-3s than farm-raised fish.

What about Omega-3 supplements? 

If needed, supplements can be taken, since most people do not consume two servings per week. When looking for supplementation, consider the level of Omega-3s you are currently consuming and dose accordingly. The National Academy of Medicine suggests a daily consumption of 1.6 g for males (ages 19-50), and 1.1 g for females (ages 19-50). Find a USP-approved label, which means a third party tested the accuracy of the product.

These supplements are found in many grocery stores at reasonable prices, yet be cautious of buying the cheapest brand. Check the label for the level of EPA and DHA- the most important Omega-3 fatty acids.

Omega-3s: Key Takeaways

1. Omega-3s can improve athletic performance by increasing muscle strength, endurance, and recovery
2. Choose Omega-3 fats for health and performance benefits by incorporating more olive oil, walnuts, chia seeds, and flaxseeds
3. Aim to consume at least two servings of fatty fish per week
4. Consider supplementation as needed to reach the recommended levels, as per the above National Academy of Medicine recommendations.

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Brittany Johnson

Brittany is a Scientific Affairs Manager at GNC (General Nutrition Centers), reviewing scientific evidence supporting sport nutrition supplements. As a certified specialist in sports dietetics, Johnson’s primary focus is understanding how to best fuel athletes for optimising health and enhancing performance.

More content by Brittany

The post Omega-3s: Why they are the real Alphas of fat for athletic performance 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.

Having a basic understanding of how carbohydrates are used during exercise can take your training and performance to the next level, and carb loading is a piece of the puzzle

By Brittany Johnson
Last updated: February 29th, 2024
6 min read

Carbohydrates – to load or not to load?

Back in high school, my water polo team hosted spaghetti nights, where the team would load up on carbohydrates the night before a big game. Maybe you’ve had spaghetti nights of your own, or perhaps heard of carbohydrate loading somewhere along the way, but is it still the best practice?
Having a basic understanding of how carbohydrates are used during exercise can take your training and performance to the next level, and carb loading is a piece of the puzzle. Let’s start by defining carbohydrates, then discuss how the body uses carbohydrates during exercise and explore what the research says about carb loading for performance.

Types of Carbohydrates

Carbohydrates are found in grains (e.g., oatmeal, farro, barley, quinoa), fruit (e.g., whole fruits and fruit juice), milk, beans, starchy vegetables (e.g., potatoes, peas, and corn), sweets (e.g., cakes, cookies, candy), and sugary beverages.

There are two main types of carbohydrates when we think practically: simple and complex. Simple carbohydrates are foods lacking fibre, such as fruit juice and sweets. Complex carbohydrates contain fibre, such as oatmeal and whole fruit. Carbohydrates are rated on a scale called the glycemic index (GI), which represents how quickly a carbohydrate-containing food increases blood sugar levels after ingestion. Low glycemic foods include green vegetables, most fruits, beans and whole grains. High glycemic foods include white rice, white breads, and white potatoes. For health benefits, such as reducing the risk of Type 2 Diabetes, our diets should contain mostly complex/low GI carbohydrates. However, in some cases, such as playing sports or exercising, choosing simple carbohydrates/high GI foods is more optimal. We will discuss that in the next section.

What’s the science on carb loading (aka – eating that plate of pasta)?

The concept of carb loading aims to increase the stored muscle glycogen in an effort to prolong endurance and/or improve performance. Low glycogen training has been shown to negatively impact exercise intensity in both anaerobic (doesn’t need oxygen to produce energy, e.g. resistance training) and aerobic (needs oxygen to produce energy, e.g. endurance training) exercise. Maximising glycogen stores can reduce fatigue during both anaerobic and aerobic exercise. However, most of the promising research shows results in aerobic, endurance-based activities.

Carb loading for short-duration activity
Very few studies have investigated the impact of carb loading on short-duration anaerobic performance. A study in male basketball players found no difference in peak power after seven days of carb loading following a four-week low carbohydrate diet. While carbohydrate loading didn’t produce higher peak power, the results from the study have implications for the importance of adequate glucose availability. After following the four-week low carbohydrate diet, the players’ performance decreased. However, after seven days of carbohydrate loading and replenishing glycogen storage, peak power returned to baseline. This means carbohydrate loading following a four-week low carb diet is effective at recovering baseline anaerobic power, emphasising the importance of glucose availability for optimal performance. Another research study looked at the impact of carb loading on jump squat power and found no improvement. So, we can conclude carb loading is not necessary for anaerobic, short-duration exercise but the amount of glucose available at the start of an activity is an important factor.

Carb loading for long-duration activity
The effects of carbohydrate loading on long-duration endurance exercise have garnered much more attention in the research world. However, the results differ depending on the event distance/duration and population studied. It’s been found that after an 80-minute rugby game, glycogen stores are no different in players who carb-load for 36-hours before the game to players who don’t. In other research based on individual running race times, carbohydrate loading failed to improve times for 10km and 25km treadmill runs. However, carbohydrate loading prior to a 30km cross-country run and a 30km treadmill run limited fatigue in well-trained athletes. Therefore, carbohydrate loading extends the time to glycogen depletion in running events longer than 30 km, ultimately allowing athletes to maintain race speed for a longer duration and improve race times. It appears endurance activities greater than 90 minutes support the practice of carbohydrate loading as an effective strategy to improve performance and exercise capacity.

Gender differences
There appears to be some discrepancies between women and men using glycogen stores during activity. Women tend to have lower resting muscle glycogen concentrations, which can impact the benefits of carbohydrate loading. Research has shown large differences in these benefits when comparing males and females. When both sexes followed a high carbohydrate diet (~75% of calories from carbohydrate foods), cycling performance increased by 45% in males and only 5% in females. Further, males managed to increase their glycogen stores by 41%, while there were no changes among females.

Knowing this, it may be beneficial for women to increase total calorie and carbohydrate ingestion during the loading phase to maximise glycogen stores.

Other considerations

An important factor to consider for carbohydrate utilisation during endurance exercise is the glycogen availability beforehand. Skeletal muscle has the ability to increase the amount of glycogen stores through training and diet. However, this does not happen overnight and needs 24-48 hours of high carbohydrate intake to occur.

While carb loading tends to favour performance benefits for endurance events greater than 90 minutes, it is just one dietary manipulation method in the tool kit for athletes. Athletes should plan their carbohydrate intake based on sport-specific and goal-specific outcomes. Overall carbohydrate intake is important pre-, post-, and possibly during (events lasting longer than 60 minutes) physical activity.

Another benefit of adequate glycogen availability for endurance exercise is improved skeletal muscle repair and recovery. Higher glycogen stores improve post-exercise muscle recovery. So, not only will that extra serving of spaghetti help you tick off that bucket list item of running a marathon, but it will aid in your recovery afterward, too – and you’ll need all the help you can get!

Summing up the pros and cons of carbs

The current research doesn’t have a clear answer, but promising results appear to benefit endurance exercise greater than 30km distances. Different results are likely contributed to small sample sizes, sport-specification, and population (e.g. highly trained athletes/males). Further, protocols for carbohydrate loading differ in research and practice. In most practices from our sport teams growing up, carb loading took place one night before the event, whereas research protocols vary, with seven days of carb loading and tapering training sessions (gradually reducing the amount of training) for 24-48 hours leading up to the event. Maybe we should have a week of spaghetti nights instead of one night before to increase glycogen concentrations more effectively! More seriously, conclusions drawn from the research imply carb loading is only one piece of the dietary puzzle that can advance performance for endurance athletes.

So, what are the practical applications for increasing glycogen storage?
The recommended dose for higher carbohydrate intake is 8-12 grams per kilogram of body weight. For example, an athlete who weighs 85kg should consume around 680-850 grams of carbohydrates. Consuming high GI foods appears to promote an increase in glycogen stores in athletes. The most important factor for carbohydrate loading is meeting the overall daily individual carbohydrate needs.

Carb loading timing strategies to increase the amount of glycogen stores include:

1.     Exercise resulting in exhaustion followed by several days of high carbohydrate intake
2.     An exercise taper combined with several days of increased carbohydrate intake
3.     A 24-48-hour high carbohydrate intake for trained athletes

While carb loading can be an effective strategy to improve your endurance performance, a holistic approach to carbohydrate availability is most important.

Key takeaways

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Brittany Johnson

Brittany is a Scientific Affairs Manager at GNC (General Nutrition Centers), reviewing scientific evidence supporting sport nutrition supplements. As a certified specialist in sports dietetics, Johnson’s primary focus is understanding how to best fuel athletes for optimising health and enhancing performance.

More content by Brittany

The post Carbohydrate loading for endurance – still a good practice? appeared first on Science for Sport.

From powder-based proteins and creatine, to gel- and gummy-based caffeine and carbohydrates, performance supplements are sold to professional athletes and weekend warriors alike. But what exactly are the advantages and risks?

By Jarred Marsh
Last updated: February 29th, 2024
6 min read

Benefits and risks of supplement usage in sports

Sports supplements have been used for decades to improve the performance of athletes from multiple sporting codes. Labeled as ‘ergogenic aids’ due to their ability to give athletes a physical or psychological boost during training and competition, performance supplements are produced in a number of different formats. From powder-based proteins and creatine, to gel- and gummy-based caffeine and carbohydrates, performance supplements are sold across the globe to professional athletes and weekend warriors alike.

But what exactly are the advantages of taking supplements? Some of these benefits include: increased resistance to fatigue, increased technical and sprint performance, improved muscular power and strength, greater sprint repeatability, and improved reaction time.

However, although these products have been shown to improve performance, the question is: are they safe for athletes to consume? The World Anti-Doping Agency (WADA) was established in 1999 and aims to assess professional athletes from all professional sporting codes and determine whether any banned substances have been used to enhance their performances. WADA releases a list of banned substances (which is updated regularly), and supplement manufacturers are responsible for reviewing this list regularly to ensure their products do not contain any of the listed prohibited substances.

Should an athlete test positive for a banned substance through WADA’s anti-doping processes, they may face up to four years on the sidelines (some may even face lifelong bans for severe infringements on the WADA code).

Growth of the supplement industry

A report published in 2021 estimated the global dietary supplement market to be valued at $US272.4 billion by 2028. The report, using data to forecast the industry’s growth to 2028, highlighted the growing demand for dietary supplements across the globe. From proteins and amino acids, to carbohydrates and omega fatty acids, the need for easily accessible products has grown rapidly across all major continents. Most recently, the COVID-19 pandemic has resulted in the demand for vitamins to skyrocket and fuel the demand for dietary supplements even further.

However, as mentioned above, not all supplements are safe for athletes to consume. Using a product that may contain banned substances can have serious consequences on both the health of the athlete and their future in the sport. There is a major risk in buying over-the-counter products without proper consultation or direction from trained professionals, and many athletes have fallen prey to this mistake, including Samir Nasri, Mamadou Sakho, “Fred” Rodrigues de Paula Santos, and even Pep Guardiola.

While the industry continues to boom, the risk of uncontrolled products increases proportionally. Most supplements are manufactured in major facilities, and therefore these products can sometimes contain traces of other ingredients not listed on the product’s container (think of a food item that lists ‘may contain nuts’ on their packaging). So while the product says it only contains certain ingredients, this is not always true.

For this reason, third-party product testing agencies were established to test products for traces of banned substances. This led to the creation of the Informed Sport certification program in 2008 to tackle this issue and protect consumers.

Informed Sport and Informed Choice Protection

Informed Sport provides confidence to athletes on more than 3,000 supplements that are tested for contamination. Through the LCG (or Laboratory of the Government Chemist), each tested batch of products from the respective supplement company’s range is screened and stamped with the Informed Sport’s logo (shown below) to assure consumers it is safe for use. However, this process comes at a cost to the supplement company.

There are other forms of certification, namely Informed Choice, Informed Ingredient and Informed Manufacturer. These programs are geared to improve on Informed Sport’s process by doing monthly retail testing on completed products, and certifying raw ingredients and production sites before the manufacturing process begins. It is important to remember that even with these checks in place, there is still no guarantee products do not contain banned substances. However, there is no process that is more rigorous to ensure contamination of products is minimised and risk is reduced.

Barriers to safe supplement use

1. Player and staff education

Although there are extensive testing and certification processes in place, there are still barriers to athletes being able to use safe products. Lack of nutrition education among staff and players can be a major stumbling block when it comes to knowing the benefits or risks of using sports supplements and knowing which products or brands are most appropriate to use (as can be seen from our list of players above). Generally, athletes will rely on the knowledge and experience of the staff in their club or association to guide them in a number of areas.

When it comes to nutrition and sports supplements, if staff and players do not possess adequate knowledge on the topic, they may be less inclined to use supplements, or they may be at risk of making poor purchases. It is therefore vital to encourage education on nutrition and sports supplements in coaching staff so they understand safe product programs (like Informed Sport), and also transfer that knowledge to their players. In this way, athletes may then understand that although many sports supplements can aid their performances, only those with the Informed Sport quality certification should be used.

Practical Tip – There are a number of product types out there that state they can help improve your performance as an athlete. However, it’s important to access information that is structured and shared by experts in the nutrition field. Some of the best open-access examples of this are the IOC consensus statement on dietary supplements and the high performance athlete, and recommended dietary supplements which are recommended for footballers, which is found on the Barcelona Innovation Hub.

2. Access to batch-tested products

Another barrier staff and athletes may encounter is access to batch-tested products. Depending on where you are in the world, you may or may not have access to an extensive range of sport supplements brands. In some areas, the number of certified tested brands may be limited – either due to supplement brands not following testing and certification processes, or lack of supply of imported tested products. Due to the lack of availability, athletes may be inclined to consume the ‘next best thing’. This is a common mistake, as someone who doesn’t understand the associated risks will assume that one non-certified protein product from a manufacturer is just as good as their certified protein-product. However, this will place the athlete at a major risk, and these situations should be avoided.

While there may be a desire for players to utilise sports supplements to help improve their performance or recovery, it is not worth the risk of facing a lengthy ban. If you cannot gain access to a safe and tested product, it is advisable to wait until you can rather than take the risk of using a non-certified one.

Future support for clubs and athletes

With the access to information around both banned substances and tested products, it is important to create an educational program for athletes and coaches to subscribe to. Through education on what makes a sports supplement safe for consumption and what makes a sports supplement risky, staff and players will be able to make informed decisions around whether to use sports supplements or not.

With the number of new sports supplement brands growing each year, and the WADA banned substances list being updated regularly, staying abreast of the changes to the landscape is vital – ultimately, you are responsible for your own health and safety.

If you’re a concerned parent, athlete or coach and you’re interested in learning more about anti-doping education and how to keep sport clean, you can register on the WADA ADEL platform to take their free short interactive courses via their Academy page.

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Jarred Marsh

Jarred has an MSc in Exercise Science from the University of Cape Town, and is currently the Head of Sport Science at Kaizer Chiefs Football Club. Jarred has experience with both men’s and women’s international football teams and has a keen interest in football conditioning and rehabilitation, as well as esport performance.

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