Olympic medals are easier to win in the afternoon: Peak physical performance is around 5pm and body clock can make the difference between a good run and a world record
- Researchers studied 144 swimmers who competed at four Olympic Games
- All swam in the heats, semis and finals which were scheduled for various times
- Data shows body clock leads to a maximum increase in performance of 0.32%
- This was the difference between first and second place in 40% of the finals
- Experts say a person can give themselves the best chance of success by altering the peak of their body clock to align with the start of the race
The time of day that a race takes place can have a deciding impact on just how spectacular the finish times turn out to be, researchers claim.
Scientists looked at swimming events at the Athens 2004, Beijing 2008, London 2012 and Rio 2016 Games and compared the heats, semis and finals by start time.
They discovered the fastest times come in the late afternoon, just after 5pm, whereas the early morning and late evening often leads to the slowest times.
Scientists studied swimming events at the Athens 2004, Beijing 2008, London 2012 and Rio 2016 Games and compared the heats, semis and finals by time of day
Researchers discovered the fastest race times come in the late afternoon, just after 5pm (pictured), whereas the early morning often leads to the slowest times
The size of the difference caused by start time is up to 0.32 per cent, often a difference of several seconds.
At the highest level of competition, this can make all the difference.
In fact, according to analysis by scientists at the University of Groningen, it exceeded the difference between a gold and silver medal in 40 per cent of the finals at the studied Olympics.
The third of a per cent variance was also bigger than the gap between silver and bronze in 64 per cent, and a bronze and no medal in 61 per cent of finals.
The study collated data on 144 swimmers who competed in the Games and featured in the heats, semi-finals and finals.
Statistically, the best times were in the late afternoon compared to the morning and evening, say scientists.
It adds to evidence that the way in which we perform over the course of a day is affected by our biological clock.
The size of the difference in race speed caused by its start time was up to 0.32 per cent, a difference of several seconds. At the highest level of competition, this can make all the difference
First author Dr Renske Lok, formerly of the University of Groningen, said: ‘In many sports, the differences between coming first or second, or winning no medal at all, are very small.
‘We wondered whether an athlete’s biological clock was playing a role.’
Body clock, or circadian rhythm, influences many things in people, ranging from core temperature to blood glucose levels.
Previous studies have found that peak physical performance often coincides with a spike in core body temperature.
However, some people have naturally different body clocks, peaking at different times of the day.
Dr Lok said: ‘Despite elaborate training schedules ranging from morning to evening hours, the time of day a race is scheduled may still affect athletes’ performance.
‘Athletes may consider adjusting their internal body clock to better match their peak performance for events with unusual start times.
‘It is possible to shift your biological clock by exposing yourself to extra daylight at the right time of day.
‘If you do this over the course of several days, you could shift the time of peak performance towards the time of a race.’
It is not yet clear whether the effect of the biological clock has an impact in other sports and swimming was studied as part of this research due to the fact many variables, such as equipment, water temperature and environmental conditions, are consistent across races.
The findings are published in Scientific Reports.