• Liverpool’s 6-minute run fitness test
• What is the most effective caffeine dosage for improving time trial performance in cycling?
• The benefits of foam rolling and dynamic stretching for golf swing performance

Liverpool’s 6-minute run fitness test

Following the conclusion of the European Championships, attention has shifted back to club football. Recently, Liverpool F.C. released a YouTube video documenting their first day of the pre-season, which garnered a remarkable one million views within three days of its publication. Notably, a particular segment of the video featuring a fitness test sparked significant discussion within the sports science community.

The fitness test, visible at the 12-minute mark of the video, involved Liverpool players running at maximum intensity around a square grid for six minutes. Some individuals have contended that the test’s simplicity is outdated, especially considering the advanced technology available in the sports science industry. While others believed a more intermittent test, like the Yo-Yo Intermittent Test, is more specific to football.

Contrarily, a post on LinkedIn by acclaimed sports scientist Gareth Sandford provided insight into the rationale behind the test. Sandford argued that “6 minutes is approximately the duration one can maintain running at VO₂ max intensity”. Consequently, he suggests that the pace sustainable for this duration could confidently determine one’s Maximum Aerobic Speed (MAS). So according to Sandford, the 6-minute run test can accurately measure aerobic fitness levels. Additionally, Christopher Hernandez Robinson also posted on LinkedIn in support of Sandford. His post discusses a scientific study showing a strong link between the 6-minute run test and VO₂ max.

Given this context, it prompts the question: was Liverpool F.C.’s six-minute run an appropriate choice for conducting an aerobic test on their first day back? Alternatively, would another aerobic test have been more suitable? We encourage you to check out the video and both Sandford’s and Robinson’s LinkedIn posts, where a thought-provoking debate has ensued within the comments section. Be sure to let us know your thoughts on the matter!

If you are interested in this subject, we have a free MAS Calculator available to download here and excellent courses on Maximal Aerobic Speed and Aerobic Conditioning for Football

What is the most effective caffeine dosage for improving time trial performance in cycling?

A recent systematic review and meta-analysis aimed to investigate the impact of caffeine on cycling time trial performance, addressing a gap in current research. The analysis encompassed 15 studies that explored the influence of caffeine on time trial performance, with performance gauged by completion time or mean power output during the trial.

The results of the analysis revealed that the ingestion of 4–6 mg/kg of caffeine significantly enhanced time trial performance. This moderate dose provided evidence that caffeine’s efficacy does not rely on high doses. The research cautioned against high doses of caffeine, which may lead to adverse effects such as gastrointestinal discomfort and reduced concentration. Interestingly, low doses of caffeine (1–3 mg/kg) were found to be ineffective in improving time trial performance.

The researchers indicated that a moderate dose of caffeine led to an approximate 2% improvement in time trial performance. They drew attention to the significance of this enhancement by illustrating that a 2% improvement in time trial cycling could have resulted in the 8th place finisher in the Tokyo Olympics securing a bronze medal by finishing 3rd.

While acknowledging certain limitations, such as the failure to differentiate between genders and consider other concurrent supplements consumed by cyclists, the research offers valuable insights for time trial cyclists. Future research in this area may also need to include the evaluation of psychological and physiological performance factors rather than just completion time and mean power output. Nonetheless, this research serves as a useful reference for determining an effective caffeine dosage for time trial cyclists.

The benefits of foam rolling and dynamic stretching for golf swing performance

A recent study has underscored the significance of an efficient warm-up in enhancing sport-specific skill execution. The study compared golf swing performance following two interventions: foam rolling and dynamic stretching of the lead hip, and repetitive golf swing practice.

The study revealed that foam rolling and dynamic stretching significantly enhanced the internal range of motion and internal rotation strength of the lead hip. Furthermore, a notable improvement in golf swing flight distance was observed when using foam rolling and dynamic stretching.

This study thus emphasises the importance of a well-executed warm-up in optimising golf swing performance. If you’re working with golfers and you notice them warming up by practising their golf swing, grab the foam roller and don’t forget to give that lead hip a good dynamic stretch!

From us this week:

>> New course: Investigating S&C Practices
>> New podcast: Elite Energy: Nutrition Strategies For Winning
>> New infographic: Beetroot Juice
>> New article: TeamBuildr: Everything You Need To Know

Access to a growing library of sports science courses

SFS Academy is an all-access membership to premium sports science education.

With SFS Academy, you’ll learn from some of the best coaches around the world as they teach you how to apply the latest research and practice with your athletes.

The post Liverpool’s Pre-season Fitness Test! appeared first on Science for Sport.

• Is zone two cardio training effective?
• Mouth rinsing may improve RDL performance
• New sports are competing for a spot in the Olympics

Is zone two cardio training effective?

In a recent YouTube video, Matt Casturo provided an insightful and instructive analysis of zone two cardio training, a topic that is often misunderstood. Zone two, which falls on the lower end of the five heart rate zones, is commonly referred to as “base training”. Casturo explains that zone two is characterised by heart rates that range between 60% and 70% of an individual’s maximum heart rate. To determine one’s maximum heart rate, Casturo recommends utilising the Bruce protocol, although he recognizes that using the formula 220 minus one’s age is simpler, albeit less precise.

Casturo acknowledges and addresses several misconceptions and challenges associated with zone two training. One significant problem with zone two training is that it can be difficult to run at a slow enough pace to maintain a heart rate within zone two. To address this issue, Casturo recommends incorporating walking periods into training routines, which can prevent the heart rate from exceeding zone two.

Another common misconception about zone two cardio training is that it is ineffective to train at such a low heart rate. However, Casturo discusses compelling research comparing Boston Marathon qualifiers and non-qualifiers. The findings suggest that qualifiers trained at low intensity for 77% to 84% of their overall training runs, while non-qualifiers trained at low intensity for only 36% to 43% of their training runs. Training at lower intensities allowed qualifiers to accumulate more training volume than non-qualifiers. Specifically, qualifiers ran an average of 40 to 46 miles per week, while non-qualifiers ran significantly fewer miles per week (23 to 35 miles).

Casturo concludes his video by guiding how to program zone two training and offering three program examples. For those interested in enhancing their aerobic conditioning or seeking to learn more about zone two cardio training, Casturo’s video is highly recommended.

Mouth rinsing may improve RDL performance

The topic of mouth rinsing for endurance performance has long been a subject of debate in the scientific community. Recently, however, there has been a substantial online discussion regarding the effectiveness of mouth rinsing for strength and power performance. The present debate was sparked by a study that found mouth rinsing to improve the performance of the Romanian Deadlift (RDL).

The study involved participants performing five sets of six reps of RDLs after mouth rinsing with a 6.6% maltodextrin carbohydrate solution and a placebo solution containing no carbohydrates. The results indicated that when participants rinsed their mouths with the carbohydrate solution, it subsequently improved the concentric and eccentric peak power of their RDLs.

While this research is promising and opens up a new potential avenue for mouth rinsing, the study had one significant limitation. The researchers failed to measure the amount of mouth rinse solution that was spat out. As a result, participants may have ingested some carbohydrates from the solution instead of merely rinsing their mouths. However, any potentially swallowed amounts should only have negligible effects on the study results.

While the results appear promising, much more research is needed before we start mouth rinsing before our RDLs in the gym!

New sports are competing for a spot in the Olympics

BBC Sport recently published an informative article regarding the inclusion of new sports in the Olympic Games. The piece provided a comprehensive overview of the logistics involved in the rigorous application process and highlighted the rapid rise in popularity of these sports. The article acknowledged the successful inclusion of new sports such as skateboarding and sport climbing in the Tokyo Olympics.

Flying disc disciplines such as disc golf and Ultimate have garnered a significant following, with an estimated 10 million players worldwide. The Chinese Flying Disc Administrative Committee reported that the new Chinese Ultimate League attracted an incredible TV audience of 1.6 billion in 2023. Teqball, a sport that combines table tennis and foot volleyball, was first showcased in 2016, and famous footballers such as Ronaldinho have participated in Teqball competitions. Dodgeball, with an estimated 67 million players globally, is another sport aspiring to be included in the Olympics.

While it may take several years for a sport to be accepted as part of the Olympics, the article highlights the emergence of new sports that could challenge and potentially replace traditional sports. As such, strength and conditioning coaches, sports nutritionists, physiotherapists, and sports psychologists must be aware of the emerging popularity of these new sports. Who knows a lot of professionals may end up working in these sports in the coming decades!

I highly recommend checking out this article which gives a glimpse into what the future Olympic games may look like. It’s a fascinating read!

From us this week:

>> New course: Hydrotherapy
>> New podcast: How Just 100g Of Resistance Can Change The Sprinting World
>> New infographic: How Fast Should You Perform The Eccentric When Jumping
>> New article: These Are The Best Open & Closed Trap Bars In 2024

Access to a growing library of sports science courses

SFS Academy is an all-access membership to premium sports science education.

With SFS Academy, you’ll learn from some of the best coaches around the world as they teach you how to apply the latest research and practice with your athletes.

The post Zone Two Cardio: THE TRUTH! appeared first on Science for Sport.

• Medvedev survives severe weather conditions at the US Open
• Offset walks: a fantastic exercise for spinal stabilization and core priming
• Dan Plexman’s incredible feel-good story

Medvedev survives severe weather conditions at the US Open

US Open finalist Daniil Medvedev expressed concerns over the extremely hot and humid weather conditions he played in at Flushing Meadows. He believes the weather conditions he experienced in his quarter-final victory over Andrey Rublev, would cause a player to “die”.

During his quarter-final match last Wednesday, the temperature rose to 35°C. Both players implemented various strategies to cope with the heat and humidity. They took lengthy toilet breaks to change their sweat-drenched clothes, hosed themselves down with cold water and used iced towels. Despite their strategies, Medvedev believed he played on “sensation” and couldn’t actually “see the ball”. Medvedev also likened the conditions to the Tokyo Olympics in 2021.

Interestingly we have a fantastic blog: Heat training: Tips from the Tokyo Olympics on how to exercise in high temperatures | Science for Sport. This blog is more relevant now than ever with the recent heatwaves across the globe. It discusses the dangers of exercising in extreme heat. In fact, Medvedev is right! Extreme heat can lead to conditions like dehydration which can be life threatening. This blog is a must read and gives great advice on how to be ‘comfortable in the discomfortable’, when exercising in the heat.

Offset walks: a fantastic exercise for spinal stabilization and priming the core

Dr Aaron Horschig of Squat University released an excellent short video clip on offset walk exercises. Offset walks are exercises performed with a barbell that has more weight on one side of the bar. Because the weight is unevenly distributed on the barbell, it creates an unstable environment. It is best to hang a weight plate from the barbell with a resistance band, which results in a “shaking” or “bouncing” weight. Using the shaking or bouncing weight creates even more instability.

While the Earthquake bar creates more instability by having a flexible bar, hanging bands off a budget barbell also works.

The aim of the offset walks is to enhance the body’s awareness and activate deep spine and core muscles. Therefore, offset walks are a fantastic exercise to help stabilize the spine and prime the core prior to compound exercises such as squats. When performing the exercise, the video suggests taking three to five steps backwards and forward for two to three sets on each side. This is worth checking out and trying!

Dan Plexman’s incredible feel-good story

There have been quite a lot of negative bulletins on sports recently. However, I came across this amazing feel-good story. This story displays why sport is beautiful and how it can positively impact people’s lives.

So, in 2008, Dan Plexman suffered a workplace accident causing third to sixth-degree burns to over 60% of his body. He was placed in a coma for 11 days and only given a 13% chance of survival. Luckily Plexman survived and he joined the Thunder Bay arm wrestling club. He hoped arm wrestling would help restore function to his badly damaged arms from the accident and offer a social outlet for him.

What Plexman would go on to achieve was nothing short of phenomenal. In 2022, Plexman won both left and right arm events at the 2022 World Championships in the disabled category. This year he placed 3^rd in his weight category at the able-bodied at the Canadian national championships. Such an awe-inspiring story!

From us this week:

>> New course: The Demands of Women’s Football
>> New podcast: The Force System – What You Need For Athletic Success
>> New infographic: Virtual Reality for Sports Training
>> New article: Needs Analysis

Access to a growing library of sports science courses

SFS Academy is an all-access membership to premium sports science education.

With SFS Academy, you’ll learn from some of the best coaches around the world as they teach you how to apply the latest research and practice with your athletes.

Get instant access when you join today on a 7-day free trial.

I hope you enjoyed this week’s roundup of the hottest sports science news, and as always, we’ll be back next week with more to keep you at the forefront of the industry.

The post Someone is going to “DIE” in a tennis match appeared first on Science for Sport.

Long journeys and jet lag are a concern for many athletes, but what exactly is the impact of long flights on performance, and what strategies are available to counteract these effects?

By Dr. Tom Brownlee
Last updated: March 1st, 2024
7 min read

Jet lag: How can athletes minimise its impact?

When I wrote this article, we were sitting in the time between the Olympic and Paralympic Games in Tokyo. Having previously written about the difficulties of the heat during the Games, I thought I’d consider another issue that was brought up frequently over the past few weeks. As with any Olympics — where people have travelled from far and wide — long journeys and jet lag are a concern for many athletes during the build-up to what could be the biggest few days of their life.

Today I’ll examine the impact of long flights and jet lag on performance. I will look at the underpinning science and strategies we might want to use to limit the effect on our next family holiday, business meeting or gold medal race.

Flying: Jet lag vs. travel fatigue

Firstly, we need to differentiate between two potential issues that may be at play when we consider long-haul travel. If we go on a long journey, let’s say a flight from London to Cape Town, this will mean a 12-hour flight crossing one time zone (during British summer time). The result of this would be travel fatigue. We would be tired from the event but would have different experiences from a 12-hour flight east, say from London to Tokyo, where we would pass through eight time zones. This second trip would be more likely to trigger the infamous jet lag that we heard so much about from British, American and many other athletes at the Tokyo Games.

We’ll start with a little explanation of the physiological difference between the two before diving deeper into the details of avoiding them.

What is actually happening to us up in the air?

Way back in 1997, the Godfather of sports chronobiology (the study of biological rhythms), Professor Tom Reilly, acknowledged the difference between travel fatigue and jet lag. He and colleagues summarised that travel fatigue, achieved via long trips (typically within three time zones of your origin), could be tackled with relative ease. They suggested this state was an acute accelerated tiredness and recommended simple amendments to training schedules and short periods of rest to allow individuals to return to normal following such trips.

They went on to acknowledge that once travelers exceeded three time zones,  experiences were much more noticeable, especially when travelling east. The exact reason for this east/west difference isn’t known, but it likely has something to do with the fact that advancing your body clock is trickier to deal with than delaying it. The general reason for our body struggling following time zone differences is that our internal body clocks become out of sync. Our brain gets confused when trying to determine the difference between where we are and where we think we are. This can also be exaggerated by novel issues such as a change in temperature, altitude, humidity, pollution etc., which has certainly been the case in Tokyo.

Beyond these factors, the key variable messing with our internal clocks is light. This is perhaps no surprise, and it is logical that if your body thinks it’s the middle of the day, but it’s pitch black outside, you may find it harder to go to sleep.

But beyond the annoyance experienced by anyone who’s ever had jet lag, from an athletic performance standpoint is it something we should be concerned with?

Jet lag and athletes: What’s the go?

It’s worth a quick glance at the science here to see what the impact of travel fatigue and jet lag might be on athletic performance. If, for example, our brains feel upside down, but we are still able to optimally perform, then maybe this would be less of an issue.

Starting with travel fatigue, it seems there is limited evidence that it might directly impact performance (assessed via counter-movement jump, yoyo test and technical/tactical performance). However, despite the potentially limited impact on physical markers, it was considered to negatively impact perceptual measures such as alertness, motivation, and mood, which would likely be a concern for athletes and coaches.

When we more specifically look at jet lag, it seems that crossing time zones increases resultant fatigue sufficiently such that performance markers including sprint and jump ability are negatively affected. It’s also suggested your chronotype (whether you’re a night owl who naturally likes a late bedtime, or a morning lark who prefers waking up early) may impact how affected you are, with larks appearing to adapt to eastbound travel more quickly.

Key strategies to reduce the impact of jet lag

Having established that, for long trips, especially when crossing multiple time zones, there are likely negative performance consequences, the big question is, what can we do about it? Below we will consider some pre-, during and post-travel strategies to help shake that funk as best we can.

Prior to travel
Firstly, it is important to try to embark on your journey in as fresh a state as possible. So, attempt to get a good night’s sleep leading up to your journey. It has also been recommended it may be useful to begin to adjust your sleep and waking time by one hour each day in the two or three days leading up to travel (especially when flying east). Greater adjustment than this is likely to be disadvantageous, with periods longer than two to three days likely to be too disruptive to an individual’s days before travel.

During travel
Once on the plane, it is recommended travellers attempt to make themselves as comfortable as possible. Many sports science departments are now taking this very seriously. During the Olympics, we saw special pillows on planes to aid rest, which you can even pick up yourself through the Team GB mattress sponsor. Incidentally, it was recently found that business class travel led to better sleep quality and quantity as well as reducing some jet lag effects – something to keep in mind if you’re looking to barter with the boss!
It has also been recommended athletes change their watches to the time at destination upon travel to aid the mindset shift. Sleep should then ideally take place during the ‘new’ night-time. Specifically, in the hour prior to attempting to sleep, it is advised to restrict computer, TV, and phone use. Loose fitting clothing, an emphasis on hydration and refraining from alcohol and caffeine have also been recommended. These interventions are based on evidence that exposure to light and noise can reduce sleep quality – aim to increase comfort and induce the physiological state required for sleep onset without pharmacological aids.

Upon arrival when having travelled west
Once you arrive at your accommodation, it has been suggested a short nap may be useful. This is aimed at suppressing the desire to go to sleep that can creep in when we extend our days by flying west. It is important, though, to keep this nap short (around 20 mins seems a good estimate) and seek some form of activity in the daytime once you’re up and about. This can lead to greater exposure to daylight, which can also aid the reduction of some jet lag symptoms.

You may also feel like going to bed 1 to 2 hours earlier than usual, subsequently waking earlier too. Don’t fret, though – this should pass after spending a few days in your new time zone.

Upon arrival when having travelled east
Things are a little trickier when we’ve flown east. This is because frustratingly, the time you feel most tired coincides with night-time in your origin time-zone, which is far from ideal if you’ve arrived into glorious sunshine at your destination. The key to cracking this and resynchronising your body clock is through manipulation of light after flying eastwards.

This comes through making the most of the positive effects of natural light at the right time. The problem with crossing many time-zones (e.g., six to nine hours) to the east is that a morning arrival worsens this issue. In such instances, the use of light shades on the plane and dark glasses en route to the immediate accommodation can minimise light exposure and allow the traveller to retire to bed until late morning if necessary after arriving. Subsequently, light exposure in the ‘new’ afternoon is beneficial.

It would also be beneficial to avoid training the first few mornings and train in the late afternoon instead.

Dreaming of gold: Take home points to maximise your performance

Generally, athletes, practitioners and us mere mortals are advised to firstly get the basics right when it comes to combatting jet lag.

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Dr. Tom Brownlee

Tom is an assistant professor in applied sports sciences and has worked with elite sports for over 10 years. Previous roles include working as a sports scientist at Liverpool F.C., where he completed his Ph.D., and working across a number of other sports. He is passionate about physiology, coach communication, and high-performance strategy and systems.

Tom graduated with a BSc in 2011 before undertaking an MSc at Loughborough University. He has published 25 academic papers on strength and conditioning, nutrition, and youth development in Sports Medicine, the Journal of Strength & Conditioning Research, and others. Tom also now supervises a number of his own Ph.D. students around the world embedded within sporting organisations.

More content by Tom

References

The post Jet lag: The impact and management of flying on athletic performance 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.

Many gym-goers wear trainers or sneakers, but some wear special weightlifting shoes with a built-up heel. And some may have no shoes at all. What is this witchcraft?

By Dr. Tom Brownlee
Last updated: March 1st, 2024
7 min read

What are weightlifting shoes?

There is generally somewhat of a timeline you work through when you first join a gym. You’ve likely found yourself there in the first place as you want to make some kind of a change – you want to be healthier, fitter, stronger … the list goes on. So, you enter.

For many, that timeline begins with the use of cardio equipment or some weight machines. They’re relatively simple to navigate and you may have even used them before. From there, you may catch a glimpse of the free weights section. You may have been told of the benefits or simply have a desire to go over there and give it a shot. And you should, it’s awesome – but that’s for a different blog. This blog will discuss one of the things you might see when you get there.

Often, you’ll see plenty of accessories on the inhabitants of the free weights section that you may not have seen before. Some lifters may have weightlifting belts, or even belts where you add weight to make pull-ups or dips more taxing. You may see chains hanging from the ends of the bars, or straps around the lifters’ wrists to strengthen their grip. But that really is just the start.

Today, we’re going to discuss what happens south of the ankle. What do these guys and girls have on their feet? Some will have the same as you, likely trainers or sneakers. But some may have special weightlifting shoes with a built-up heel. And some may have no shoes at all. What is this witchcraft? Is this the secret of the weights room that’s been shielded from the cross trainers and rowing machines for so long?
Well, we are going to have a look through the science to help us understand the pros and cons of these approaches and figure out which might be the best one for you to get the most out of your sessions.

A brief weightlifting intro

Allow me first to address something that I’m a bit of a stickler for. Weightlifting and weight lifting are different. Weightlifting is what you see in the Olympic Games. It’s the snatch and the clean and jerk. Weight lifting is anything where you pick something heavy up for some kind of athletic reason, often in the gym – confusingly, this can also include weightlifting! The reason for this pedantry is to clarify  what I’m talking about throughout the rest of  this blog.

What do weightlifting shoes do?

Firstly, it’s important to point out that no non-weightlifter needs weightlifting shoes. If they aren’t in your budget right now, then don’t worry – you can still master solid techniques without them. In fact, some coaches actually recommend not using them at first, so you don’t become overly reliant on their benefits. But what are those benefits and why do people wear weightlifting shoes?
We mentioned earlier that weightlifting shoes have a built-up heel – this is the secret to their benefit. If you’ve ever performed a squat, you may have struggled to get as low as you were aiming. This is often a result of having poor mobility at the ankle. It’s something that can be improved over time but certainly isn’t something that will change overnight. A raised heel helps with this by increasing the tibial (shin) angle, meaning that for the same bend at the ankle, you’re able to get down lower. In fact, when wearing weightlifting shoes, you actually bend your ankle less and compensate by bending more at the knee and hip than when wearing normal trainers.

This can also lead to helping more experienced lifters to maintain a more upright torso during some lifts – something that can be really advantageous as it keeps the centre of mass towards the middle of our base of support (basically, directly above and in the middle of our feet). This is especially important as the load increases because it prevents us from losing balance and dropping the weight in front or behind us. It also makes the lift a little easier too.

These changes in position are not to come at the expense of improved mobility and technique, though. In fact, this trunk position benefit has not been shown in less trained back squatters wearing weightlifting shoes. However, considering all we’ve discussed, it seems weightlifting shoes would be advantageous in either of the Olympic lifts as well as other similar movements, including squat and leg press variants.

Beyond the change in shin angle provided by the heel, the wedge itself is very firm. So, unlike a cushioned trainer, when you push down hard during a lift, none of that force is absorbed into the shoe. This is really effective when you get to your heavier loads as you can utilise all produced force in the lift and not lose any through the compression of your shoe heel. It’s the same principle that led to some very quick sprint times at the recent Olympics. In Tokyo, it was the track track that was firm, meaning all force the athletes produced was rebounded back by the springy soles of their shoes, keeping them moving quickly.

Having said that, it’s important to highlight that weightlifting shoes are not essential. Similarly, it’s also important to point out that you don’t need to be an advanced lifter to want to own a pair either. If you’re enjoying lifting and would like some of the benefits, then go for it.

What about lifting barefoot?

We mentioned at the start of this blog that you may have spotted some people lifting in the gym with no shoes on at all. That seems fairly counter-intuitive, keeping in mind what we’ve just said about the benefits of a weightlifting shoe. However, again, this is all about putting you into a better position during the exercise you’re doing. If you’re deadlifting for example, you don’t want to be too far from the floor (as you would be with an elevated heel) because it’d be much harder to get low enough to pick the weight up. In this case, you want to be as low as possible, so you have to move the weight over as small a distance as possible.

This is why many opt for barefoot lifting or wearing very thin-soled shoes, like Converse. Beyond these positional benefits of lifting barefoot, some also suggest it can lead to greater increases in strength. This may be a result of having to work harder when lifting like this, as it requires you to constantly stabilise yourself (a job typically made easier by your shoes), which may be beneficial depending on your goals.

As hopefully you know by now, these blogs are based around science, so let’s have a quick skim around the research to see how that influences our decisions around barefoot lifting. It does indeed appear there are benefits to deadlifting barefoot for the reasons previously stated. The need to lift weight over a greater distance when wearing shoes does lead to an increased force requirement, whereas lifting barefoot makes shifting the same load easier by decreasing that distance, hence, the force required. Having said that, these small differences are likely only of value when lifters are very close to their personal bests. Interestingly, some individuals also prefer squatting barefoot despite the evidence above for a heel raise helping such movements. This may be a preference of some, but it seems that there is no biomechanical advantage obtained in doing so.

While we’re on barefoot lifting, it’s worth a quick public safety announcement to say to be careful when doing so – accidents in the gym do happen!

Some other options

If you’re interested in weightlifting shoes and their benefits but aren’t totally sure about buying some just yet, you might be wondering whether there are any other other options. Well, one quick fix is to use an external wedge under your heel to bring about some of the same advantages. You may have seen this in the gym too, and not really know why people were doing it. The easiest way is to use a small (1.25 or 2.5kg) weight plate under each heel. This has been shown to provide a beneficial position, especially if you’re new to moves such as squatting. This gives the benefit of a more advantageous ankle position before you’ve acquired your new pair of shoes. 

How should weightlifting shoes fit?

If you are interested in purchasing a pair of weightlifting shoes, then ideally, you want to try some out to see how they fit and feel. Brands such as Nike, Inov-8, Risto, Reebok, and Adidas are good places to start. A good retailer will let you try them on and even go through a few unweighted moves to give you the best chance of bagging a pair that feels comfortable and works for you.

Take homes

Weightlifting shoes can offer a real benefit in some of the big lifts in the gym. They can also help if you have mobility issues, though shouldn’t be used at the expense of working on any mobility deficiencies. You shouldn’t feel limited without them or compelled to get a pair, though. Plenty of exercises are not aided by them, and there are even alternatives, such as using an external heel raise if you’d prefer. Barefoot lifting also has some benefits – just be careful not to drop anything on your feet! 
If you are interested in investing in a pair, it is best to try on a few different brands to see how well they fit you and how they feel when you go through the key movements. If you do end up wearing a pair in your local gym, just remember one thing: It doesn’t mean you no longer have to re-rack your weights, no matter what anyone tells you!

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Dr. Tom Brownlee

Tom is an assistant professor in applied sports sciences and has worked with elite sports for over 10 years. Previous roles include working as a sports scientist at Liverpool F.C., where he completed his Ph.D., and working across a number of other sports. He is passionate about physiology, coach communication, and high-performance strategy and systems.

Tom graduated with a BSc in 2011 before undertaking an MSc at Loughborough University. He has published 25 academic papers on strength and conditioning, nutrition, and youth development in Sports Medicine, the Journal of Strength & Conditioning Research, and others. Tom also now supervises a number of his own Ph.D. students around the world embedded within sporting organisations.

More content by Tom

The post Weightlifting shoes: Are they really needed (and what about going bare feet)? appeared first on Science for Sport.

Paralympic athletes can teach able-bodied athletes key lessons about the training process, including how to use injuries as a time to make massive physical gains, how to adjust exercises to suit individuals, and how to work together with coaches to get the most out of training.

By Matt Solomon
Last updated: March 1st, 2024
8 min read

What can we learn from Paralympic athletes?

Paralympians take superhuman to the next level. What is more elite than being able to outrun the world on blades? …. I’ll wait.

Last year’s Tokyo Paralympics brought us a feast of unbelievable sporting feats, from dramatic comebacks to mind-blowing world records, but what can the everyday athlete learn from the world’s best Paralympians?
As a strength and conditioning coach for the Dutch Olympic team, specialising in Paralympic sport, I am fortunate to have worked with a few of the world’s best, and I think there are three key lessons any athlete can learn from these world-beaters, and no, it’s not perseverance or motivation. If you are interested in the latter, check out episode 81 of the Science for Sport Podcast.
Firstly, it’s important to state that although the way Paralympians train might seem a world apart from the way most able-bodied athletes do, it’s not. They are getting up early, lifting weights, going to practice, getting their conditioning in, eating well, and might even be studying on the side. So if they are so similar, where specifically can you learn from their example?

1. Never regret an injury

When you get injured, which you will (sorry to be the bearer of bad news), you need to know how to keep your fitness levels up. In fact, top athletes will be using the time during an injury to work on aspects of physical fitness they normally wouldn’t be able to train.

This idea becomes clear when we look at Paralympians. Most Paralympians won’t be able to train in the same way as their able-bodied counterparts, which means some areas of their fitness training need to be adjusted or even stopped altogether.

This adjustment means there are opportunities in other areas. Let’s say a Paralympian is unable to use their lower body – this gives the athlete far more time and energy to invest in training their upper body, and this can lead to some amazing adaptations. For reference, check out the physiques of some of the world’s top wheelchair basketball athletes, or you can listen to how they train in episode 73 of the Science for Sport Podcast with Mariska ‘The Beast’ Beijer.

Using this same logic, able-bodied athletes who are injured could be investing their precious time and energy into improving other areas of their fitness, which they wouldn’t otherwise have been able to train. An example might be a football player (or ‘soccer player’ to anyone who thinks a World Series can be held in only one nation) who has an injury. Instead of sitting on the sofa watching Netflix and moaning that their teammates are out there having fun and working hard at training, the footballer could be working on increasing muscle mass, strength, or aerobic capacity, all of which are tough to train optimally when you’re rammed full with games.

So, lesson one is to make the most out of your injured periods, and see opportunity in even the most frustrating situations. But Matt, I hear you cry – I got injured and I can’t train properly. Don’t worry, I’ve got you covered, you just need to adjust your exercises.

2. Always pick the best exercises

Have you ever been performing an exercise and thought ‘this doesn’t feel right for me’? Well the chances are there is a much better option out there for you, but society tells you that, for example, you need to squat and deadlift, so you carry on.

One of the biggest lessons you can learn from adaptive athletes is there are always alternative exercise options which will still get you great results. You shouldn’t be married to one exercise or one method – if you or your coach are, it’s a red flag.

Paralympians will often need adjusted exercises, whether that’s because they have a prosthetic leg and can’t do a bilateral back squat, or they are unable to use their hand to grab a dumbbell. Adjusting the exercise to suit the person is crucial to get the necessary adaptation.

Taking the example of an athlete with a single leg amputation – they might be better served by splitting their leg exercises into two unilateral (single sided) variations, as opposed to one bilateral (both sided) version. This means each leg individually gets the stimulus which it needs to progress.

Taking this philosophy and applying it to an able-bodied athlete could be quite simple. Let’s take a 210cm basketball player who hates bilateral back squats. Most likely this is a combination of poor ankle mobility and comically long upper legs. There is no police force coming to arrest you if you chose a different squat, so using a unilateral version instead might make things easier, as you no longer have to rely on ankle mobility to hit depth. The result is the athlete can squat more comfortably, and still get the required adaptation.

Another example might be an athlete who has an injured hand – they may still be able to load the arm, but at the wrist. In this instance, they may want to attach a cable at the wrist to perform any number of shoulder or elbow-based exercises.

 

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The list of exercise adaptations is endless, but the key thing to remember is there is always a way to get the adaptation you want – sometimes it just means a different exercise or setup.

But Matt, I again hear you cry, this is difficult, and I could probably use some help thinking of the exercises I need to adjust. Read on dear friend, I’ve still got you.

3. Teamwork makes the dream work

This is the biggest lesson – no matter who you are or how you are training, working together with your coaches will help you to take your performance to the next level.

Making the time to speak directly with your coach will help them to understand you better, and also help you contribute to your program, which can be highly motivational. It allows you to take ownership and responsibility, and ultimately this can lead to better results.

When working with Paralympians, it’s safe to say most of the time they know their bodies better than their coaches. This means, when it comes to making a program for them, working together is essential if you want the best outcome.

You could be in the same boat – ultimately you know your body better than anyone else. Your coach needs to ask you the right questions so they provide you with the best possible training plan.

You may also have important knowledge that your coach doesn’t yet know. For example, some exercises might always cause you pain or irritation – this is important to share with the coach who can make the necessary adjustments.

 

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In practice, this means sitting together and discussing the goals of the athlete and the coach, before getting into the nitty-gritty of exercise selection and adjustment. During the discussion, the athlete might describe preferred exercises, or methods they’ve tried before and how they perceive their training. The coach is then able to match this to the physical adaptation they are looking to achieve, and together you can make a training program where the sum is greater than the individual parts.

This works particularly well with increasingly experienced athletes, who have a good perception of their body and their training. With experienced athletes, these planning sessions can become more of a negotiation than anything else. This was particularly clear during our preparations for the Tokyo 2020 Paralympics. In this instance, I sat with some athletes to negotiate the volume, load, and exercises in the sessions. The athletes wanted to do more, and it was my job to hit the sweet spot between optimal physical and optimal mental preparation.

With time, these discussions allow the athlete to get skilled-up and educated enough to have more and more influence on their program; ultimately the coach becomes a consultant, and both athlete and coach work together as a team to achieve their shared goals.

So if you want to get the best out of yourself, you’ll need to get the best out of your coach too – it’s likely that together you will make a far more effective program than as individuals.

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Putting knowledge into action

Paralympians can teach able-bodied athletes a tonne of great lessons – the list is far longer than just these three. However, if you want to get the most out of your training, these three lessons can be a fantastic starting place.

The general theme of these lessons is to make the training sessions, where you invest all your time and effort, as individual as necessary to reach your true potential. Note, I am not saying every exercise needs to be individualised to the athlete. However, it is often the case with more advanced athletes that increasingly specific stimuli are necessary to optimise their performance.

For coaches, this means creating an environment where this level of attention to detail is possible – for example by setting aside time to sit one-on-one with your athletes, or by creating training systems to speed up the training prescription process.

For athletes, it means asking for enough of your coach’s time to get the results you need, getting to know your body as well as possible, and staying critical when it comes to the training methods you undertake. Of course for athletes with fewer resources, this may mean you have to do a lot of the hard work yourself – athletes at all levels can keep asking the questions ‘why am I doing this?’ and ‘is it making me better?’ – whether you ask these to yourself or a coach may depend on the level of sport you are playing.

If you don’t have access to a crack team of sport scientists or strength & conditioning coaches, you might want to consider taking some simple steps. It would be good to develop a big list of exercises in your locker – practicing more exercises means that when you need to adjust, you’ll have a quick alternative.

For those without a large exercise library stashed away in their brains, you can ask yourself an easy question: ‘could I hold this differently’? This can be applied to pretty much any exercise which uses equipment like a barbell, dumbbell, or cable. One example might be for an athlete who is unable to press overhead (like a dumbbell shoulder press), due to pain or lack of mobility – replacing this with a landmine press could allow the athlete to keep developing their shoulders, without pain or discomfort.

As you can see, exploring your movement options by questioning whether you can achieve a similar result while using a different method, could be a game-changer when you need to adjust your training.

Some final thoughts

Paralympic athletes can teach able-bodied athletes key lessons about the training process, including how to use injuries as a time to make massive physical gains, how to adjust exercises to suit the individual athlete, and how to work together with coaches to get the most out of your training.

The application of these lessons can help any athlete reach their maximum potential.

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Matt Solomon

Matt is a strength and conditioning coach at Team NL (Dutch Olympic Team). He was also the Lead Academy Sports Scientist/Strength and Conditioning coach at Al Shabab Al Arabi FC. For Science for Sport, Matt works as the group manager for the Coaches Club and is the host of the Science for Sport Podcast.

More content by Matt

The post Three key lessons that able-bodied athletes can learn from the Paralympics appeared first on Science for Sport.

Once the Olympic flame has been extinguished and the world moves on, what comes next for athletes who struggle to adapt?

By Dr. Will Vickery
Last updated: March 1st, 2024
6 min read

How does an Olympic athlete cope in a post-Olympics world?

For two weeks every four years – if you discount the year just gone – we get swept up in the magic of the Olympics, glued to our screens and forever chatting about the moments that were and those that could have been. But for those competing, an Olympic cycle can cover several years and be over in a flash.

For an athlete, the lifecycle of an Olympics campaign goes well beyond what we see in those two weeks. We hear so many stories about the monstrous number of hours spent on the track or in the pool as athletes ply their trade, the sacrifices to their personal and social lives, and their ability to overcome injury or adversity. Years of planning, training, and refining have gone into making sure that an athlete is in the best possible position to perform on the world’s biggest stage.

But once the flame has been distinguished and the world pushes the Olympics to the back of its proverbial mind, what comes next for the athletes? And importantly, how do they navigate this sudden change?

Beyond Tokyo: What happens next?
For us common folk, after all is said and done, the Olympics seamlessly fades into a collage of fond memories, and we all resume our regular work and sleep schedules. But despite most performing to the best of their ability, the reality is, most athletes aren’t boarding the plane home with a medal – and this can really be a tough pill to swallow for some.

Quite often, an athlete’s sense of identity is linked with their athletic ability, and “underachieving” is something that they might struggle with. Interestingly, Andrew Bennie and his colleagues recently found many athletes have a negative post-Olympic experience. In fact, those who failed to meet their perceived performance expectations (whether winning gold or hitting a PB), or were generally dissatisfied with their performance overall, experienced long-term psychological distress as a result.

The rise and fall of the “Olympic celebrity” is something which athletes often have to navigate, particularly on their arrival home. Following the 2016 Olympics in Rio de Janeiro, Howells & Lucassen reported that those who did not medal were often met with a sense of unaccomplishment from the general public (as perceived by the athletes). As you can imagine, thinking that you are not worth someone’s time just because you didn’t place in the top three would really start to play with your head.

For those who are not fortunate enough to simply continue their athlete careers (e.g. soccer players heading straight back into their national leagues), another factor they have to contend with is getting on with their pre-Olympic lives. At the end of the day, an athlete is no different to the rest of us, but having to go back to work or completing mundane, everyday tasks just isn’t exciting. Again, Howells & Lucassen highlighted how after the 2016 Olympic Games, a number of the athletes they spoke to felt completely unmotivated or genuinely disinterested in their “normal” lives.

It’s not all doom and gloom
I should clarify that in most cases, the Olympics, for both those competing and those watching from the sidelines, is a really positive experience. You’ve only to see the joy on the faces of the athletes after winning gold or when they make their way through the stadium at the opening or closing ceremony to realise this. Feeling a sense of pride and honour at being able to represent their country is also something athletes often quote about their Olympic experience, alongside achieving their childhood dreams of being an Olympian.

Referring back to the study of Bennie, opposed to their “underachieving” counterparts, athletes who were satisfied with their performance, regardless of the outcome, seemed to manage their wellbeing and were generally quite positive about their post-Olympic experiences.

Depending on the success and popularity of an athlete, there is sometimes a significant financial outcome after the Games in the form of prize money. For example, Singaporean gold medallists at this year’s Tokyo games will receive an astonishing US$1,000,000. Some athletes even manage to gain sponsorship deals after they have finished competing, think Michael Phelps and Reese’s. Something new for these Tokyo games is the impact of social media and athletes acting as influencers. A change to the IOC’s Rule 40 means athletes can now engage with fans whilst advertising for their personal sponsors to further help them financially.

Being an Olympian, particularly these days, really does have some perks.

What can be done to improve the wellbeing of athletes after the Olympics?
There are no finite rules to how an athlete should manage their wellbeing since, as we all know, everyone is different and likely to respond differently to the same stimulus. In most cases, though, the responsibility of managing and guiding an athlete’s wellbeing and ensuring they are in a positive state of mind falls to their coach. Bennie and colleagues offer a few recommendations on how the coach of an Olympic athlete can help foster a positive mindset post-Olympics:

To the athletes (and coaches) of the future…
If you find yourself donning your country’s colours on the world stage, make sure you set some time aside during your preparations, and even during your Olympic campaign, to think about and plan for what comes next. You need to be aware that the spotlight is not always going to shine on you, and being able to manage this effectively will go a long way in helping you to maintain a positive outlook on things.

As for coaches, an athlete’s wellbeing is their responsibility, before, during, and especially after the games (or any big event for that matter). So, making sure that athletes understand what comes next is imperative to achieving a positive state of mind and a successful transition back into life following the closing ceremony.

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Dr. Will Vickery

Will is a Lecturer of Sport Coaching at Deakin University, Australia. Prior to this he has worked with Cricket NSW and Cricket Australia in an array of roles ranging from a sport scientist, development coach and a strength and conditioning coach. He completed his PhD at the University of Newcastle, Australia within the area of practice design.

More content by Will

References

The post Olympic letdown? How does an elite athlete cope in a post-Olympics world? appeared first on Science for Sport.

What is the science behind exercising in high temperatures, and what can be done about it?

By Dr. Tom Brownlee
Last updated: March 1st, 2024
1 min read

Heat training: How to cope when the going gets hot

 
To say the Tokyo Olympics has encountered some bumps in the road would be somewhat of an understatement. The biggest of these obviously being Covid-19, which sees the Games unfolding with many compromises in place. Early in the Games though another issue was cited as a potential problem for many of the athletes. I’m not referring to the collapsible cardboard beds designed to ‘deter multiple occupancy…’, but the stifling Tokyo summer weather.

At times, the temperatures have risen above the typical July highs of 30°C (86°F), which many have already found difficult to cope with – Norway’s Kristian Blummenfelt, who took gold in the men’s triathlon, though impressively stated that he was disappointed that the race wasn’t hot enough.

But let’s look at why high temperatures can be an issue during exercise, what Blummenfelt and others have done to combat such potential pitfalls and what tips you can take for your own training and competition.

The heat is on

When we exercise in normal conditions our core temperature increases. This increase can quickly reach up to 2°C, which may not sound like much but causes some significant changes in the body. During exercise in warmer environments, our cooling mechanism (sweating) increases. Though this system can be beneficial, it can leave you open to dehydration if you don’t take the right precautions.

Potential dehydration occurs because of two things that happen when we sweat.

1. We lose water from our body – this causes our blood to get slightly thicker, which means our heart must work harder to keep it pumping (think of trying to squeeze a pump full of honey compared to water for an extreme example). This makes exercise more difficult.
2. We also lose salt that is found in our sweat – this will impact how well our muscles are able to function (and is one of the reasons we get cramp more quickly in the heat).

There are a few things we can do to combat any downturn in performance though.

A balancing act

Firstly, and perhaps most obviously, we need to drink to replace what is lost through sweat. Not only does this maintain our blood volume but it also keeps our sweating, and therefore cooling system, efficient. Initially, make sure you’re hydrated when you start. This is most easily done by making sure your urine is the colour of pale straw.

Then while you’re exercising aim to drink when thirsty. A combination of water, electrolytes (salt) and carbohydrate (sugar) has been shown to be best at maximising fluid uptake. Most sports drinks will provide a balance of these, though lower sugar versions may be better when doing shorter activity where additional energy isn’t required (though that’s a blog for another day!).

Make sure you drink it though. A friend once told me of an elite marathon runner who picked up his bespoke formulation while racing and promptly poured it over his head. I’m confident the bees enjoyed it more than he did!

Comfort in discomfort

One training technique employed by athletes who are soon to compete in hot environments is to train in similar conditions during the build-up. This can come from exercising somewhere warmer or by experiencing it artificially using things like heat chambers. Physiologically, this trains our body to sweat more, which aids cooling. It also leads to increased blood volume to allow the heart to cope better once sweat rate increases.

This links back to Blummenfelt’s bold statement about Japan not being hot enough. Being from Norway, his team knew they needed to address the heat and opted for training in Yokohama in the build-up to the race to reduce the shock he experienced during the big day. GB Hockey have also cited use of heat chambers as one of their secret weapons in being prepared for the heat. They’ve in fact said they feel so well prepared that they no longer see the weather as an issue.

Put it on ice

Finally, having considered how we can adjust our physiology during the lead-up to competition, the next step is to keep that rising core temperature at bay when we compete. Drinking more to replace sweat and improving our sweating ability is great in dry heat. But in the 80+% humidity of Tokyo, the evaporation of sweat, which is the bit that actually keeps us cool, can be difficult.

The science here tells us that we want to reduce our temperature as much as possible before we start, this allows us greater room for our internal thermometers to increase once we start working. GB Rowing are reported to be using ice vest and bracelet technology to create this gap in temperature.

Research review: Does aerobic fitness help beat the heat? 
For us this can be as simple as placing our hands into cold water before we compete. Our hands have a very high surface area so make them perfect for rapid cooling using a technique like this. Similarly, cooling strategies during our events as we saw in the triathlon where athletes were sprayed with cold water and given cold bags to put on their pulse points can help.

Take homes

Admittedly, most don’t have the luxury of moving their training or competition venue to cooler climates as they’ve done with the race walking and marathon – although it’s still 28°C (82°F)! Nor are they able to move events to a 6:30am start time as they did in the triathlon (difficult to convince your Sunday league manager potentially).

But by following some of the key messages above from the pros, you can increase your tolerance to heat, reduce drops in performance and increase your internal temperature gap over the competition.

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Dr. Tom Brownlee

Tom is an assistant professor in applied sports sciences and has worked with elite sports for over 10 years. Previous roles include working as a sports scientist at Liverpool F.C., where he completed his Ph.D., and working across a number of other sports. He is passionate about physiology, coach communication, and high-performance strategy and systems.

Tom graduated with a BSc in 2011 before undertaking an MSc at Loughborough University. He has published 25 academic papers on strength and conditioning, nutrition, and youth development in Sports Medicine, the Journal of Strength & Conditioning Research, and others. Tom also now supervises a number of his own Ph.D. students around the world embedded within sporting organisations.

More content by Tom

The post Heat training: Tips from the Tokyo Olympics on how to exercise in high temperatures appeared first on Science for Sport.

By James de Lacey
Last updated: April 20th, 2024
15 min read

Contents

1. Introduction
2. Should Transgender Athletes Compete In Female Sports?
3. Argument 1 – Sport Is Unfair
4. Argument 2 – There Are No Differences Between Genders
5. Argument 3 – The Power of Testosterone: Does reducing it really make it fair?
6. Argument 4 – Advantages Don’t Mean Medals
7. Are There Any Real Solutions?

Introduction

It’s one of the hottest topics in sport – the debate on whether transgender females should compete in cisgender female sport. With the recent qualification of Olympic weightlifter Laurel Hubbard for the Tokyo 2021 games, this argument has been reignited and doesn’t seem to be getting any less controversial.

Rarely grounded in science, the debate is often fuelled by a mixture of emotion and political correctness, with added concerns of inclusivity and fairness. Arguments based on emotion or personal views tend to lead to incorrect facts and misinterpreted science. That’s why this topic so complicated.

Now, I am all for having the right to do what you want with your body, and have no problem with anyone who wants to transition from male to female or vice versa. The problem comes when physicality and competition are involved. But before we get into it, I want to preface this piece by clarifying that I will solely be referring to male-to-female transgender athletes. (Author’s viewpoints are their own).

Should Transgender Athletes Compete in Female Sports?

Find any news article shared on social media about a transgender athlete competing in a cisgender female sport, and it’ll be littered with comments expressing opposing views. Some believe transgender female athletes should be able to compete in cisgender female sports, while others believe they should have their own category, or not compete at all. Here are the common reasons why many believe they should be allowed to compete in female categories:

• Sport is unfair by nature. We allow bigger, stronger cisgender females to already compete, so why can’t transgender females also compete?
• Gender is a social construct, so there is no difference between males and females. So, anyone should be able to freely compete in any division.
• Transgender females need to undergo hormone therapy for at least one year to reduce their testosterone levels to be under those identified by the IOC or IAAF. This should render any advantages they may have null or even a disadvantage. Alternatively, some believe that testosterone isn’t the reason for performance differences in the first place.
• Certain transgender females aren’t even going to win, so why does it matter?

These are the four most common arguments in favour of transgender females competing in cisgender female sports. I’m going to break down each point and illustrate why they go against conventional science. To quote my favourite science educator Neil deGrasse Tyson: “The good thing about science is that it’s true, whether or not you believe in it.”

Argument 1 – Sport Is Unfair

One of the top reasons many believe transgender females should be allowed to compete in cisgender female sports is fairness. The IOC guidelines state their stance for transgender athletes to compete against cisgender females is to “guarantee fair competition” (1).

Sport is already inherently unfair. Athletes with access to better coaching, facilities, and resources have an advantage over those without. Also, some athletes are naturally gifted with talent or physical attributes that others will never possess, even with years of training. This means shorter athletes may lose out to taller athletes in basketball, and smaller athletes may lose out to larger athletes in rugby.

These examples of unfairness in sport can be considered “tolerable unfairness” (2). Tolerable unfairness is grounded in the idea that athletes begin from roughly the same starting point but ultimately end up at different levels due to uncontrollable factors (2). There are some instances where tolerable unfairness is controlled to ensure it is more tolerable and doesn’t overshadow more important aspects of performance, such as skill.

While the “skill thesis” has issues, the initial premise is sound. It suggests that if sport was to be decided based purely on skill, any genetic advantages would need to be mitigated through handicap systems or luck scales. After all, that is the purpose of competitive sport – to identify the most skilful (3). This is the very reason that combat sports have weight classes – if a heavyweight matched up with a lightweight in any combat sport, the heavyweight is likely to win purely because of their size advantage – it would be difficult to determine who was the most skilful.

If a transgender female has a performance advantage over a cisgender female athlete, there’s a chance that she also might win a contest without being the most skilful (2). So, any advantage they may have should ideally be considered as tolerable unfairness, or have some controlling factor introduced to lessen its effect. This isn’t necessarily possible though, because the performance advantages that transgender females may have are not only because of their size but because of what caused them to grow in the first place – more on this later.

While gender is a social construct where all can be viewed as equal, sex is biological. So is there really no difference between males and females?

Argument 2 – There Are No Differences Between Genders

Let’s start at the top – the elite of the elite. Below is a graph showing the clear performance gap between males and females at the elite sporting level (4). With female performance set to 100%, we can see that endurance-based sports have a performance gap of around 10-13 % in best performances, whereas strength and power-based activities have differences up to 50 %. It seems there is a trend where the more upper body that is involved in the activity, the greater the performance gap. Previous research suggests males are more often than not bigger, faster, and stronger than their female counterparts (5). This has been found in several sports including handball (6) and weightlifting (4) where performance differences range between 31-3 7% across all weight classes. Females who are 60 % heavier than males still don’t make up this performance gap difference.

Figure 1. The male performance advantage over females across various selected sporting disciplines (4).

These are the elite performers. But does this performance gap exist in amateur athletes? In young adults, VO₂max in males was 56 % higher than females (7), with two separate studies finding males possess 89 % one-rep maximum(1RM) strength, 57 % greater muscle size, 109 % greater isometric strength (8), and 162 % greater power than females (9).

We can go even further with performance differences between males and females pre-puberty before any hormonal changes.

Nine-year-old males are 10 % faster over short sprints (10), 16 % faster over 1-mile, jump 10 % further, do 33 % more push-ups, and have a 14 % stronger grip than 9-year-old females. Performance differences are even seen in children as young as six-years-old where males can perform 16% more shuttle runs and jump 10% further (11).

With all of these performance differences from young children ranging to elite athletes, what would happen if male and female divisions were abolished and anyone could compete against anyone? Well, we would likely see the end of females competing in some high-level sports. For example, the world record 100 m sprint time for females is 10.49 seconds. The 100 m sprint record in the U18 men’s category is 10.06 seconds – set by a 16-year-old boy.

So, it seems there are clear differences between males and females when it comes to physical performance and physical attributes. But what is it that is causing this large performance gap?

Argument 3 – The Power of Testosterone: Does reducing it really make it fair?

There is one hormone that influences these dramatic performance differences between males and females, and that is testosterone. Testosterone is a sex hormone considered highly beneficial in all sports for enhancing many physical attributes. As the IAAF stated in their 2019 eligibility regulations, “To the best of our knowledge, there is no other genetic or biological trait encountered in female athletics that confers such a huge performance advantage [than testosterone].”
The average male testosterone level sits between 7.7-29.4 nmol/L. The average female ranges from 0-1.7 nmol/L (12). Raising testosterone outside of a normal female range is so potent that even at levels just below the lowest male range of 7.3 nmol/L, we see 4.4 % increases in lean muscle mass, 12-14 % increases in lower body strength and power, and a 26 % increase in upper body power (12). This testosterone level is 156 % greater than the female average.

In fact, when males hit puberty, their testosterone levels increase 20x whereas female’s testosterone levels remain steady, resulting in males having a 15x higher testosterone than females (12).

These data suggest that testosterone through puberty is primarily responsible for these large performance gaps between males and females. Even at the early to middle stages of puberty, males exhibit testosterone levels of approximately 6.9 nmol/L which is far greater than the average female (12).

As this movement of inclusivity in sport grows, there are more and more people trying to discredit testosterone as a powerful performance-enhancing hormone.

However, scientific research suggests otherwise. The simplest way of discerning the effects of testosterone on performance is to study the effect of exogenous testosterone (i.e. supplementing extra testosterone) in males and females.

Let’s start with muscle mass and strength.

Figure 2. the strong dose-response relationships of muscle mass shown as (A) “lean” or “fat-free” mass or volume of (D) thigh and (E) quadriceps muscle and (C) of leg muscle strength with increasing testosterone dose (12).

Figure 2 represents increasing doses of testosterone in males and its effect on muscle mass, leg press strength, thigh muscle volume, and quadriceps muscle volume (12). We can see a clear dose/ response relationship between testosterone and body composition, strength, and muscle mass, meaning the more testosterone is used, the greater the gains that are made.

But what about females? Do they show the same response?

Figure 3. Dose-response effects on lean (muscle) mass and three measures of muscle strength as a result of increasing doses of weekly testosterone enanthate injections in women (12). 

As demonstrated in Figure 3, the same dose-response relationship is evident in females as in males; increases in muscle mass, leg press strength, chest press power, and lower body power.

So, what exactly does more testosterone do to the human body? Well, testosterone has a strong effect on bone density where males exhibit 10% greater bone surface area compared to females (2). Greater bone surface area allows more muscle to be supported which is one reason why males are generally bigger and stronger than females on average.

Additionally, males on average are 7-8 % taller than females with longer, denser, and stronger bones that allow greater leverage in sports that involve jumping, throwing, and explosive activities (12). Further, females suffer more lower body stress fractures compared to males due to the difference in bone density.

While many believe that testosterone only improves muscle mass and strength, it also has a large positive impact on aerobic capabilities. Males have a diaphragm that sits lower than females allowing for greater lung capacity. During puberty, increases in testosterone increase the quantity of alveoli (small air sacs) in the lungs allowing more oxygen to travel from the lungs into the bloodstream.

Males also have a larger heart, increasing stroke volume. Females will pump 33% less blood per heartbeat compared to males.

Finally, males display greater haemoglobin concentrations improving the ability to carry oxygen to the working muscles during exercise. All of these attributes are influenced by testosterone (2).

With all of these positive impacts related to testosterone, what is the limit for a transgender female to compete? The current IOC guidelines for transgender female athletes are as follows:

1. They have to declare their gender for sporting purposes to be female for at least four years.
2. Their testosterone must be under 10 nmol/L for at least 12 months before competing.

The IAAF guidelines have since lowered the required testosterone level to 5 nmol/L which they state is to “ensure a level playing field for athletes” (19). If you remember, the average female testosterone is 0-1.7 nmol/L. And levels approaching the lower range for males is enough to significantly enhance performance and body composition in females.

But what about the belief that transgender females are at a disadvantage because they have to suppress their hormones? There is a strong body of research investigating male-to-female transitions and the effect of hormone therapy on various performance markers. Unfortunately, it seems that reducing testosterone in transgender females doesn’t reverse all of the adaptations cisgender males undergo during growth.

After 24 months of hormone therapy, transgender females retain their bone density and, in some cases, may even be preserved over 12 and a half years (13, 4). After 12 months of hormone therapy, no increases in bone fracture rates were found to support retaining bone density (14).

The largest reduction in muscle mass seen in male-to-female transitions is 12% after 3 years of hormone treatment (21). When looking at a 1-year timeline, as per the IOC guidelines, we see an approximate 3-5% loss in muscle mass (15).

The fact that cisgender males on average have 40% greater muscle mass than cisgender females, suggests that transgender females have large advantages in this department over their cisgender female counterparts (4).

After eight years of hormone therapy, muscle mass is only reduced by 17% placing them in the 90th percentile for women and grip strength is reduced by 25% placing them 25% higher than cisgender female values (4). Further, when testosterone is reduced to within the normal cisgender female range after 12 months of hormone therapy, grip strength is only reduced by approximately 4% (18).

Let’s take the hot topic and use Hubbard as an example. Her previous records before transitioning in 1998 were a 135 kg snatch and 170 kg clean & jerk, for a total of 300 kg.

21 years later in 2019, she hit a 131 kg snatch, and 154 kg clean & jerk in competition for a total of 285 kg. That is a 5% decline in performance. When there is a 30 % strength difference between males and females in Olympic weightlifting, that doesn’t bring her much closer.

While no research to date has measured the effects of male-to-female transitioning with hormone therapy on endurance performance, the research suggests that transgender females retain most of the lean muscle mass, strength, and bone density even up to and past eight years in some instances.

Even with all these advantages, some transgender females still don’t have a chance of winning elite competition.

Argument 4 – Advantages Don’t Mean Medals

This is often a viewpoint parroted on social media, and there is some truth behind it. Not every transgender female competing at the elite level is going to surpass all cisgender female athletes. There are a lot of factors that make up a truly elite athlete, from skill level to genetic background.

But there are many reasons why, regardless of whether they win or not, allowing transgender females to compete with cisgender females is a slippery slope.

Firstly, there’s the matter of fairness. A cisgender female could potentially lose her spot for selection because of the advantages a transgender female has. The cisgender female athlete is not allowed to supplement with exogenous testosterone to match the transgender athlete. Further, cisgender females haven’t gone through the surge in testosterone that occurs during puberty, leaving them even further behind.

But it’s not just the elite level that suffers. It’s the amateur level, too. For example, Gabrielle Ludwig, the 6’6”, 230 lb transgender female played college basketball (21). And Hannah Mouncey, the Australian Rules football player playing in the VFLW who previously represented Australia in men’s handball at 6’2” (22). Most recently, France has allowed transgender females to play women’s rugby in France (23). As it becomes more acceptable for transgender females to compete at the elite level, it will continue to trickle down to the amateur game.

While transgender females may not medal at the elite level, at the amateur level, the average male who transitions can potentially compete at a much higher level than they could as a cisgender male. This creates a small butterfly effect – their advantage may allow them to reach the representative level or win local events, which means a cisgender female athlete at that level doesn’t get scouted or selected. This can mean a lack of scholarship or sponsorship, potentially leading to the athlete leaving the sport altogether.

Are There Any Real Solutions?

Many believe if males transition before puberty, the effects of testosterone will be negated as they wouldn’t have been exposed to high levels of testosterone. However, as previously discussed, children as young as six show a large performance gap favouring males. Consideration also needs to be given to the teens undergoing female-to-male transition. Mack Beggs, the American high school wrestler won the Texas State girls’ wrestling championship with a combined 89-0 record throughout both seasons whilst using steroid therapy treatment whilst transitioning from female to male. Texan public high schools require students to compete under the sex assigned at birth, though Beggs stated, “[Texas policymakers] should change the laws and then watch me wrestle the boys. Because I’m a guy. It just makes more sense.” (24).

It seems that suppressing testosterone to the cisgender female range still isn’t enough to mitigate the performance advantages transgender females have. UK Athletics has called for an open category allowing transgender athletes to compete with men, protecting the female division. However, this has been contested by the UK government highlighting that the Equality Act 2010 does not allow the exclusion of transgender athletes on grounds of fairness (25).

However, at this point, there aren’t enough transgender females to warrant this (perhaps a case of ‘build it and they will come’?). The evidence isn’t yet comprehensive enough to provide a clear answer, and until the research is conducted, there is unlikely to be an immediate consensus.

James de Lacey

James was the Head Strength & Conditioning Coach for the Romanian Rugby Union. He has previously worked in America’s professional rugby competition Major League Rugby with Austin Elite and the NZ Women’s National Rugby League Team. He is a published author and has completed a MSc in Sport & Exercise Science from AUT, Auckland, NZ.

More content by James

The post The Laurel Hubbard debate: The science behind transgender athletes appeared first on Science for Sport.

1. Summary
2. Why is hydration important for athletes?
3. What is hydration testing?
4. Why is hydration testing important?
5. How is hydration measured?
6. Are there any issues with hydration testing?
7. Is future research needed with hydration testing?
8. Conclusion
9. References
10. About the Author

Summary

The practice of hydration testing has been implemented for the past couple of decades, with new and more advanced technology capable of detecting smaller changes in an athlete’s hydration status becoming available in more recent years. Hydration status can influence a range of physiological functions in the human body relating to both performance and health, therefore, regular testing is advised.

Many forms of hydration testing exist, most of which are discussed in this article. For any practitioner, it is essential to fully understand the validity or reliability of the testing method, and how this can be compromised in different situations.

Why is hydration important for athletes?

Staying hydrated each day is crucial for many reasons: to regulate body temperature, keep joints lubricated, prevent infections, deliver nutrients to cells, and keep organs functioning properly. Being properly hydrated also improves sleep quality, cognition, and mood. In addition to this, dehydration also impairs sports performance. Ensuring athletes are properly hydrated is therefore very important.

Exercise or physical activity takes place in many different environmental conditions, for example, in climates which vary greatly in terms of temperature and humidity. This, in conjunction with a range of other factors, such as fitness level and metabolic rate, can cause an increase in core body temperature and effectively increase perspiration (i.e. sweating) (1). In humans, the primary method of heat loss is sweating (2), and this can be substantial during vigorous exercise, especially in warm and humid environments.

Sweat not only contains water but also electrolytes which are important for the optimal function of the human body (3). Loss of these important molecules can not only have a detrimental effect on performance, but also on health (4), and as such, it is useful to implement protocols capable of detecting these changes in hydration status. Hydration testing can take many forms depending on the available resources and how much time the practitioner is willing to dedicate to it.

This article will summarise the three main methods often used to assess hydration status in athletes, as well as common issues associated with these methods. It is important to note there is not one particular method which suits everybody in every scenario, instead, the practitioner must carefully consider which method is right for them and their athlete(s).

What is hydration testing?

Hydration testing is a protocol used to determine an athlete’s body fluid balance. An athlete with a normal body fluid balance is said to be euhydrated (5). This euhydrated status is not a specific point, but rather a state of normal body water. Disturbances to an athlete’s body fluid balance can cause severe performance and health defects (3, 4) hence why hydration testing can be a useful component of athletic programmes. When the athlete is in their euhydrated state, they are more likely to be able to perform at their full capacity than if they are dehydrated (6).

Many hydration testing methods have been developed and implemented, the most common of which include:

• Body Weight Changes
• Bioelectrical Impedance Analysis
• Urine Specific Gravity
• Urinary indices
• Blood Indices

Whilst there are numerous methods for assessing the hydration status of athletes, each of them have varying levels of validity, reliability and practicality.

Why is hydration testing important?

It is important to maintain the body’s state of homeostasis as much as possible before, during and after exercise, as this helps to ensure the athlete can perform at their very best and recover adequately.

In terms of fluid balance, the goal prior to exercise is to have the body in its euhydrated state (7). Pre-performance (e.g. training or competition) hydration testing can, therefore, determine if the athlete is in a sufficient state of hydration, and thus ready to participate at their absolute optimum.

Dehydration and Performance
During exercise, a 2% or higher reduction in an athlete’s body weight has been shown to decrease both aerobic and cognitive performance (8, 9).

There is evidence to suggest that an increase in an athlete’s core temperature can decrease their motor-neural output during exercise. This can have a negative effect on their exercise tolerance time and their drive to exercise in the heat due to serotonergic mechanisms (10).

As mentioned before, dehydration can affect aerobic performance. This is because body water deficits can result in an increase in cardiovascular strain due to an increased heart rate and decreased stroke volume; ultimately resulting in a decrease in cardiac output. Dehydration can also lower cardiac filling due to a reduction in blood volume, this is often accompanied by a rise in skin blood flow and skin compliance (8).

There have been mixed results when reporting the relationship between dehydration and muscular strength and power. Whilst there have been reports that dehydration does affect muscular function (11, 12), there are also contradicting results (13, 14). This suggests that this is an area for future research in order to determine if there is a relationship between dehydration and muscle functioning.

Dehydration and Injury
The previous section explained how dehydration can affect the central nervous system, effectively causing fatigue. However, there are other health risks that dehydration poses to an athlete, such as cramps, hyponatraemia and heat stroke (this will be covered in the next section).

Despite the extremely high prevalence of exercise-associated muscle cramps (EAMC), the aetiology of this condition is not well understood (15). There are three hypotheses to determine the aetiology of EAMC:

• Dehydration hypothesis
• Electrolyte depletion hypothesis
• Altered neuromuscular hypothesis

Whilst there is not an overwhelming amount of scientific evidence for either of the three (15), it seems as though the altered neuromuscular hypothesis has the more likely pathophysiological mechanism for EAMC. Basically, exercise will cause muscle fatigue which will, in turn, increase excitatory afferent activity and decrease inhibitory afferent activity. This leads to altered neuromuscular control which then affects alpha motor neuron activity leading to EAMC. Although, it is important to recognise the number of factors that will determine the severity (e.g. exercise intensity, duration, conditioning level) (15).

Prolonged exercise (> 5 hrs) can cause hyponatraemia, which is defined as having a diluted blood sodium concentration in the body (7). Hyponatraemia is caused when an individual consumes fluids low in sodium or sodium-free water and does not replace the necessary electrolytes lost (16). As a result, marathon runners seem to be prone to hyponatraemia when they do not implement effective hydration strategies (17).

There also seems to be a relationship between the severity of the symptoms (e.g. nausea, headache, confusion and fatigue) and the amount by which blood sodium concentration have fallen (18).

Dehydration and Death
As previously touched upon, there can be serious health risks for individuals who exercise whilst dehydrated. In some extreme cases, there have even been several reports of death due to heat stroke, with dehydration said to be a contributing factor (19).

Heat stroke is diagnosed when the following criteria are met (16):

• Body temperature reaches 40.5 °C or greater
• Presence of cognitive function impairment
• Anidrosis (absence of sweating)

To prevent this from occurring, there are natural neurophysiological processes in place to maintain homeostasis. Thermoregulation is the process in which heat is dissipated from the body in order to maintain an optimal core temperature (37 °C) (20). A rise of just 1° can activate the body’s thermoregulatory centre, which can then act to reduce the body temperature through several mechanisms (20), one of which being perspiration (i.e. sweating).

It is proposed that dehydration reduces cardiovascular function, which, therefore leads to a decrease in skin blood flow and the inability to lose heat via sweat (8, 21, 22).

To summarise, given the impact hydration can have not only on performance but also on health, this firmly demonstrates the importance of having some form of hydration strategy in place to ensure athletes are well-informed and monitored.

How is hydration measured?

There are a number of different ways to measure an athlete’s hydration status, each with its own levels of validity, reliability and practicality.

Urine Specific Gravity (USG)
Urine Specific Gravity (USG) is the density of a urine sample compared to the density of water (6). The density of the sample is determined by its osmolality, as well as the concentration of a number of molecules such as urea, protein and glucose. There are three main methods of testing an individual’s USG (6).

1. Hydrometry: The density of the sample can be tested using a weighted glass float (6). This method is considered to be inaccurate and impractical due to daily calibration being needed, a large urine sample, and also because it is temperature sensitive (6, 23).
2. Refractometry: This involves a light being passed through the sample and measuring how much the beam has refracted (23). In contrast to hydrometry, it requires a smaller sample and internally corrects for the temperature; making it a more practical and inexpensive option for measuring hydration.
3. Reagent Strips: These strips offer a more simple approach than refractometry and hydrometry. The strips react to the number of hydrogen ions released in the sample, which ultimately affects the pH and is detected by the Bromthymol blue contained in the strip (23). As the pH decreases (indicating an increase in H+ ions), the strip changes colour to a more yellow-green. A colour kit can then be used to estimate the sample’s USG.

Bioelectrical Impedance Analysis (BIA)
Bioelectrical Impedance Analysis testing can take the form of many types, these include:

• Single Frequency BIA
• Multi-Frequency BIA
• Bioelectrical spectroscopy (BIS)
• Segmental BIA
• Localized BIA
• Bioelectrical impedance vector analysis (BIVA).

This article will mainly focus on SF-BIA because it is of relatively low cost, portability and practicality (24). Whilst it has been criticised for its poor accuracy in subjects that have significantly altered hydration levels (e.g. in clinical settings), it can still be used to estimate total body water (TBW) in subjects that are normally hydrated; such as athletes (24).

The science behind this approach is quite simple: it involves an alternating current passing through the body (50 kHz) and the resistance to the current is measured (6). There are a number of ways that this can done, such as using gel electrodes that are placed on both wrists and ankles or using a stand-on platform with hand-held devices (6). The data received depends on the model of equipment used, some devices provide an estimation of total body water stores, whereas others provide raw data and calculations must be used to further predict the athlete’s body composition (6).

This method is seen to be safe, rapid and easy to administer, however, the machine used to calculate the estimations can be quite costly. The positive side of that is that there is minimal technical skill required to work the machine. The accuracy and precision of results can be affected by a number of factors (25) such as:

• Food, drink and alcohol: fasting for > 8 hr is recommended
• Generator: correct calibration
• Electrode position: clean with alcohol first, with minimum of 5 cm between electrodes
• Physical exercise: no exercise for > 8 hr prior
• Subjects: height and weight need to be correctly calibrated using a stadiometer and scales closest to the nearest 0.5 cm and 0.1 kg respectively.

Body Weight Changes
Body weight changes have been used in the past to measure acute changes in hydration status (26). This method’s popularity with sporting clubs can be accredited to the fact that it is a simple, non-expensive and non-invasive tool that can provide a quick estimate of an athlete’s so-called hydration status.

The principle behind measuring an athlete’s body weight before and after exercise to estimate hydration status is relatively simple. It is assumed that 1 ml of sweat represents 1 g of mass lost (2). The mass loss can then be used to express the post-training BW as a percentage of pre-training BW through the following equation:

Mass Loss (%) = [BW (post) / BW (pre)] x 100

For example, if an athlete weighed in at 78 kg before training and weighed out at 76.8 kg after training, the equation would read [76.8 kg / 78 kg] x 100 = 98.5 %, meaning a mass loss of 1.5 %.

However, it is important to note that there are many factors that could limit the reliability and validity of the results. Using this method assumes that all mass lost during exercise is only due to sweat, but many other factors can contribute towards mass loss (26). Some of these include:

• Respiration
• Substrate oxidation
• Urination and excrement

From a practical perspective, this method uses minimal equipment, is quick to conduct, is cost-effective, and can provide a quick estimation of an athlete’s hydration status immediately after exercise. However, it is important to understand the different variables that can affect the reliability of the results.

Urinary Indices
Hydration status can be measured by monitoring characteristics such as volume, colour conductance and osmolality (6). Under normal conditions, the amount of urinary volume excreted can range from 1.5-2.5 L/day, with the colour a pale to light yellow and an osmolality of < 500 mOsm/L (27). When exercise commences, water conservation mechanisms are activated in the kidneys to ensure that both plasma volume and intracellular water are maintained, this has an effect on the aforementioned urinary characteristics.

Measuring the athlete’s urinary volume quantitatively (i.e. how much the athlete has urinated that day) requires a large amount of compliance and cooperation from the athlete; however, a more qualitative method can be used, such as asking the athlete the frequency of urination during the day (6). Both approaches require a degree of athlete education to ensure that the data collected is accurate.

Measuring urine osmolality involves the collection of urine and using a freezing point osmometer to determine the number of solutes (e.g. NaCl) per kg of solution (6). This requires a trained technician and also expensive equipment, though there is an alternative. The use of a Sparta 5 Conductance Metre has been validated in previous research (28). This method uses a 5-point scale to provide feedback regarding the conductance of a person’s urine and provides immediate feedback which is simple to use.

A 6-point Likert Scale can be used to estimate hydration status through urinary colour (29). Copies of the scale can be distributed between athletes. This is non-invasive, non-expensive and simple to use, however, the athlete must be educated to ensure that they use to scale correctly and must take note of the results.

These methods to estimate hydration status through urinary indices may prove invalid if there are large acute ingestions of fluid after exercise (30, 31). This may produce diluted urine and mask their true hydration status (6). Methods must be put in place to ensure that hydration testing is completed as soon as possible after exercise so that the data collected is as accurate and precise as possible.

Blood Indices
It is thought that a number of blood-borne indices can be used to test the dehydration status of an athlete. Hypertonic dehydration (e.g. from profuse sweating) can be detected through changes in plasma osmolality and plasma sodium (30, 32), whilst hypotonic or isotonic dehydration can be detected through serial haematocrit or haemoglobin measurements (33).

This method requires a properly trained professional to ensure that safe and sterile measurements are taken with the appropriate laboratory equipment. Examples of which are outlined below:

• Freezing point osmometer (Plasma osmolality)
• Ion selective electrode (Plasma sodium)
• Centrifuge and capillary tubes (Haematocrit)
• Spectrometer (Haemoglobin)

This method of hydration testing can be costly, invasive and labour-intensive (6). Due to the fact that it requires blood sampling, there will always be a risk of infection, bruising and vein damage.

There have been studies that clearly show that a loss of > 3 % BW during exercise results in an increase in plasma osmolality (30, 32). However, there is contradicting research regarding the sensitivity of blood osmolality when < 3 % BW has been lost (34). From this study, they concluded that urinary measures may be more accurate during conditions of mild dehydration; which other research supports (29). This could be due to the fact that urine is more concentrated to maintain normal blood chemistry during exercise (6). Adding further contradiction and complexity, one study even demonstrated that plasma osmolality was highly responsive to a reduction in BW by < 1 % (30).

Plasma sodium has been found to increase under conditions of dehydration (32). This study aimed to investigate the use of plasma sodium as a marker of dehydration during exercise in heat. It involved 2 hours of cycling (3.7 % BW lost) and a further 21 additional hours of fluid retention. Results show an increase in plasma sodium from baseline measurements, and an extra 20 minutes of cycling (1.5 % BW lost) showed a further increase in plasma sodium.

One study compared haematocrit and haemoglobin levels to levels of total body water both before and after an exercise intervention lasting 14 days (33). It showed that blood indices correlated with total body water throughout the study, suggesting that these may be useful for situations of hypotonic and isotonic dehydration.

Whilst plasma osmolality, blood sodium, haematocrit and haemoglobin may provide accurate information regarding hydration status, the limitations outlined earlier seem to outweigh the benefits at this point in time. Further research and engineering are needed to provide a more practical approach when using these measurements.

Are there any issues with hydration testing?

Limitations regarding hydration testing primarily appear to be related to its practicality in the field. For example, it would be impractical to have an entire AFL or Rugby League team use BIA after every training session or to use USG to estimate hydration level. Unfortunately, due to the current technology, to implement a method that is appropriate/practical (e.g. BW changes), measurement accuracy will, most likely, be sacrificed. Coaches, fitness and medical staff must communicate what they feel is the most appropriate method for their particular sport.

A further issue with hydration testing can be the priority that this measurement takes in the eyes of the fitness and medical staff. Coaches outside of an elite environment may not have the time or resources to hydration test their athletes, potentially putting their performance and health at risk.

Is future research needed with hydration testing?

Future research in the area of hydration testing should focus on determining if current methods can be altered so that they can provide an even more valid and reliable measurement as well as addressing the following issues:

• The effects of acute rehydration after exercise as net weight gain is not an acceptable method of rehydration assessment as it fails to monitor fluid replacement in both the extracellular and intracellular compartments of the body (6). This is where measures of urinary and blood parameters can play a part in determining an individual’s hydration status both before and after exercise.
• Indices such as potassium, sodium and protein may be appropriate hydration tests (6), but no methods are currently available which are simple, quick and low-cost.

Conclusion

Hydration testing is a very important part of any athletic programme and can prevent serious performance and health deficiencies. There are methods available which are valid, inexpensive and non-time-consuming, but the confounding variables that may affect results must be addressed. The method that best suits the practitioner/coach and their environment will depend on several factors; such as the resources available and the time-cost.

Future research is required to assess whether urinary and blood indices can be used as hydration tests in a practical sense.

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