Mammoth’s Chief Scientific Officer, Dr Jonathan Bloomfield talks about the important role sleep plays in athletic performance.
In recent posts, I’ve been writing about how much we need to take our sleep more seriously. As I have made clear, I’m a big advocate of optimising sleep to improve everyday health. In this article, I wanted to shine a light on one group in society that is already taking sleep seriously – the high performance athletes.
Have you noticed that when athletes and managers talk to the press, they now mention the words “fatigue” and “recovery” more than they may have done in years gone by. This is no surprise when we consider the lengths that professional sports teams and sporting bodies are going to in the pursuit of performance gains.
Understanding fatigue and recovery
There are many factors that contribute to fatigue, including physical, mental, emotional and social elements. Over time, the accumulation of fatigue can have a drastic impact on our health, wellbeing and (critically for athletes) performance. It is the role of scientists like myself to measure and influence the fatigue–recovery balance as much as we can to help high performance individuals and teams achieve performance gains and reduce risks. These risks can include illness, injury, burn-out or simply lack of concentration.
Fatigue specialists like myself have developed systems of monitoring “workload”. We measure how much (volume), how hard (intensity) and how often (frequency) “work” can be undertaken without having a detrimental impact on health. We talk about getting individuals into a state of “readiness” – a state where the athlete has returned to a satisfactory level of wellbeing and performance so that they can go for another effort. If an athlete is not ready for work – perhaps a match or tough training session – then we say that they are in a “state of compromise” that may lead to underperformance or injury. At times, it can be a very fine line.
For example, how often have you seen a Premiership football player’s performance begin to drop midway through a season only to improve after a couple of games off. Squad rotation and managing workload has become an essential part of the professional game. And you might be surprised to see how much work goes on behind the scenes to monitor data, assess player fitness and safeguard against burnout.
When it comes to recovery, you may be aware of sports stars who use unusual and bizarre practices to help them feel refreshed and full of energy. Take Andy Murray’s ice baths at Wimbledon, Michael Phelps’s cupping at the Rio Olympics or Mo Farah’s oxygen tent before London 2012, for instance. While these strange habits may grab the headlines, the most powerful methods of recovery are still widely accepted to be nutrition, hydration and sleep.
Over the past 10 years, sleep has increasingly being regarded (and respected) as a major contributor to athletic development and on-field performance. Much of this can be attributed to the rise in professional staff and trends of sophisticated monitoring procedures at professional clubs. As money has flooded into sport and the world has become more commercially minded, the culture within teams and organisations has visibly changed.
As the bar has been raised, the margins between winning and losing have become finer.
To achieve success, lifestyles have changed and aspects such as poor diet, smoking and alcohol consumption are no longer acceptable at the elite. And neither is poor sleep. Entire teams of support staff have been brought in to implement changes to exercise and recovery plans. Many of the changes are informed by detailed research, such as the landmark studies that have illustrated how quality sleep can benefit athletes.
Cristiano Ronaldo claims he targets nearly 12 hours of sleep per day to be in his best condition and he rates his bedroom as the most important room in his house.
“I spend nearly half a day [in bed], because, you know, to perform good, to be at a good level, you have to rest good. So I’m always resting.”*
A number of research studies have been performed by Stanford University within their athletic population to show that “extended” sleep length plays a significant role in athletic performance. Allowing student athletes to reach up to 10 hours of sleep over a period of 7 weeks produced significant performance improvements across several different sports including:
- 8% improvements in 15m speed
- 20% improvement in reaction time off the block
- 10% turn time efficiency
- 19% increase in kick-strokes
Collegiate Basketball Players
- 9% improvements in free throw shooting accuracy
- 9.2% improvement in 3 point shooting accuracy
- 0.7 sec faster sprint time over 95yards
- Overall improved mood and wellbeing scores
Collegiate Tennis Players
- 1.5 sec faster at tennis sprint drill
- Significant improvement in serving accuracy
- 42% improvement in hitting depth drill
- Overall improved mood and wellbeing scores
Roger Federer is another top athlete who testifies to the importance of sleep for him to be at the top of his game. Reports have suggested that he regularly sleeps 9-10 hours a night (not bad with 2 sets of young twins!) and reports of up to 12hours a night earlier in his career. Considering he recently won his 19th Grand Slam on the brink of turning 36 (becoming the oldest player to win a Men’s Singles major title in the Open era) there is a clear argument for linking sleep and recovery with career longevity and sustainable high performance.
What happens while we sleep?
It’s important to note that while science is taking great steps forward in understanding the process of sleep and the effects of sleep on the body, our knowledge of the night-time hours is still in its infancy. However, there are strong indications that a number of processes take place while we sleep.
Physical and mental repair is thought to take place at night as the hormone surges of the day, such as adrenaline and testosterone, die down and the body rebalances cortisol levels to regulate stress.
Once asleep, the body also typically sees a spike in growth hormone production, which is directed to areas of the body where it is needed most. This contributes to the development of our muscles and bones, and the regulation of our metabolism. We also get an increase in the hormone prolactin, which helps to reduce any inflammation.
During sleep the breathing rate slows and deepens, delivering more oxygen to the bloodstream than when awake and at rest. Our brains and central nervous systems develop to recognise, restore and refine the motor skills we have learnt, as well as the context of when to apply them through experiential learning. To put it a different way, all the things an athlete learns during coaching sessions, competitive matches and analysis meetings is consolidated at night. These skills eventually develop to the point of automation and instinct when athletes are World Class.
Something worth noting is that problems only arise when athletes consistently lose sleep. Athletes can often experience a single bad night of sleep, particularly before a big event, but this short-term loss does not seem to have a major impact on how they will be able to compete the following day. What’s more concerning is when sleep loss is more regular to creates an imbalance in the autonomic nervous system, which controls our body’s essential functions.
How does this present itself?
Brain function and cognitive abilities are often the first thing to suffer, as decision making skills, judgement of distance and speed and reaction time begin to fail. There has also been some evidence produced that shows perceptions worsen around feelings of pain, depression, tension, confusion, fatigue, anger and vigour (which negatively affects mood, motivation and competitiveness) and there is also a higher susceptibility to gain illness due to workloads and immune suppression.
There may be several factors why top athletes (and coaches!) may experience continual sleep loss based on situational, medical and behavioural factors including:
- Scheduling and types of training (e.g. early morning weights)
- Scheduling of competition and congested fixtures (e.g. afternoon/evening kick off)
- Scheduling of travel
- Poor sleep habits and hygiene (e.g. over-arousal)
- Irregular sleep/wake & nap timings,
- Hotel beds & unfamiliar surroundings
- Post-match media and corporate responsibilities
- Light exposure (natural and artificial)
- Jet lag (plus connecting with loved ones at home on a different time zone)
- Chronotype (night owls vs intermediates vs larks)
- Over hydrating leading to increased bathroom visits
- Pain and injury
- Overuse and or ill-timing of caffeine
- Stress, anxiety, depression
- Studying for exams
- Medical sleep disorders (e.g. Insomnia, RLS, Apnea)
In June 2017, a Stony Brook University study published some really interesting findings in the journal SLEEP highlighting that players who sent tweets between 11pm and 7am the night before a game scored on average 1 point less and their shooting accuracy dropped by 1.7% compared to their personal performances which did not follow late-night tweeting. They also took fewer shots, rebounds, steels and blocks and played an average of 2 mins less per game.
Sleep research into sport is still relatively new and is quite a difficult topic and population to have controlled experiments within. Instead, each club should be aiming to learn quickly about the sleep needs and habits of their staff (playing, coaching and support teams) and considering scheduling appropriately and not to contribute further to group sleep loss. Similarly, players should receive adequate, and personal, sleep education with an aim of developing a healthy respect for the role sleep contributes to their development, performance, injury risk and career longevity.
In recent years a study was released predicting career longevity in Major League Baseball. The research tracked the sleep habits of 80 players across 3 seasons to discover that at the end of year 3, 72% of players with normal sleep traits were still playing, 39% of players with poor sleep traits were still playing and only 14% of players with severe sleep issues were left still playing.
There’s also some evidence linking a chronic lack of sleep with increased likelihood of developing an injury. Again, looking at the sleep and injury histories of a teenage student population in 2014 involving 160 athletes, a study revealed that hours of sleep per night and grade at school were the best independent predictors of injury. When these teens slept for an average of less than 8 hours per night, they were 1.7 times more likely to gain an injury over those who had slept for more than 8 hours.
Whether you are an elite athlete or everyday hardworking individual, improving your rest and recovery can help you to reach goals, achieve more and maintain a greater overall level of health and wellbeing.
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