Back in December 2013, the BBC announced some FIFA World Cup fixtures would be changed and played at different times of the day due to extreme weather conditions. But while many coaches have welcomed the changes, few have taken into consideration how it could affect a player’s biology and physiology.
This is because studies show an athlete’s body is programmed to peak at certain times of the day. It’s related to something called their circadian rhythm, a 24-hour cycle of physiological processes where hormones rise and fall based around when we wake up and go to sleep.
Research published in the journal of Sports Science calls this particular school of thought chronobiology and boxers understand this better than most as they adjust their training camp and sleep patterns so they peak on fight night. Talking about this concept of peaking at certain times of the day, Gene Kilroy, who ran Muhammad Ali’s camps, was quoted on the website Inside HBO Boxing saying: “It’s a matter of getting the body acclimated to the change.”
So should players at the World Cup be altering their alarm clocks to gain an athletic advantage, and should coaches be concerned about fixture changes interfering with their players’ circadian rhythm? Or will they peak and play at their optimal level regardless of the time of the day?
Interestingly, studies show this could be more important than we first thought, and any coach who has even a basic understanding of chronobiology could have an athletic advantage this summer.
One person who does understand this is Liverpool Football Club owner John W. Henry. According to The Guardian newspaper, he flew Luis Suarez 16,859 miles on his private jet so he could travel in comfort for his World Cup qualifying game for Uruguay on Wednesday to then play for Liverpool on Saturday. This was all in an effort to avoid jet lag, which is when the body’s internal clock, or circadian rhythm, is disrupted by travelling and changing time zones.
Illustrating its importance, The Guardian also reported Kagisho Dikgacoi of Crystal Palace similarly made a 11,268-mile round trip for South Africa's game with Spain in Johannesburg. However, without the comfort of a private jet caring for his circadian rhythm, he didn’t even make it onto the pitch.
Obviously it’s hoped players won’t be suffering from jet lag, but scientists from the School of Human Sciences at Liverpool John Moores University, in the aforementioned sports journal, believe the circadian rhythm still affects performance even without 16,859 mile flights. They stated:
The majority of components of sports performance, e.g. flexibility, muscle strength, short term high power output, vary with the time of day and peak in the early evening close to the daily maximum in body temperature.
Seeming to support this idea is a study conducted by the Department of Kinesiology at the College of William & Mary in Williamsburg, USA. They took 10 healthy, male subjects and tested the strength of their leg contraction at 8 a.m., 12 p.m., 4 p.m., and 8 p.m. Results revealed muscle performance was better in the evening during the faster movements.
They theorised this was because the activation of fast-twitch muscle fibres, those needed for strong and quick movements, was far better when the body’s core temperature was higher, which tends to be in the evening compared to the morning.
Finally, it's believed a match later in a player’s day would also be hormonally more beneficial. Scientists from the School of Human Movement Studies at Charles Sturt University in Bathurst, Australia found that the body’s testosterone-cortisol ratio is better in the evening compared to the morning.
Put simply, this is more conducive to optimal performance since testosterone is a hormone related to speed, strength, power and aggression while cortisol is related to stress. So when testosterone levels are highest relative to cortisol levels, players are better-equipped hormonally for the full 90 minutes.
Therefore, based on these findings it appears England should be physiologically firing on all cylinders in their first group game against Italy, which has now been moved to 6 p.m. local time, according to The Guardian. But they may need to adjust their alarm clocks and get up earlier for their match against Costa Rica, which is played at 1 p.m. local time.
Lastly, I completely acknowledge that although the theory may support the idea of coaches manipulating their team's circadian rhythm to gain a physiological advantage, implementing such science could prove impractical.
For instance, Roy Hodgson may find it difficult to get Wayne Rooney to sleep and awake on demand to peak his testosterone, body temperature and muscle activation. But chronobiology is an interesting, and often overlooked, aspect of sports science, and if a coach has even a basic understanding of it, it could be the competitive advantage needed.