Cell: The outcome of that big sporting event you just can't wait to watch
may depend on how the timing of the match aligns (or doesn't) with the
internal biological clocks of the athletes on the teams, according to a
study reported in the Cell Press journal Current Biology on January 29. Athletes and coaches would do well to make note and adjust their schedules accordingly, the researchers say.
The study found that the performance of competition-level athletes
varies over the course of the day by as much as 26%. People who would
naturally prefer to sleep in will give their best performances hours
later in the day than early birds will.
"If a one percent difference in performance can make the difference
between 1st place and 4th place in a 100 meter race and actually win you
the gold medal at the Olympics, then imagine what a 26 percent
difference in your performance could give you," says Roland
Brandstaetter from the University of Birmingham in the United Kingdom.
"Our research takes us away from the idea of 'time of day of the race'
and directs us more to internal biological time."
In other words, he says, what time is it for your body clock?
Earlier reports had suggested that athletes' personal best
performances are always in the evening. But those studies had not
actually taken into account whether those athletes were night 'owls' or
morning 'larks.' While an individual's circadian phenotype often does
shift from childhood into adolescence and adulthood, there are real
physiological differences between people based on their natural
sleep/wake patterns.
Brandstaetter and his co-author Elise Facer-Childs used a novel test
to characterize the circadian phenotypes of more than 120 athletes.
They then selected 20 athletes representing early, intermediate, and
late types and tested their cardiovascular endurance in a standard
fitness test at six times of day.
Those fitness tests revealed considerable variation in individual
performance over the course of the day. The best predictor of how well
those groups performed at a given hour was the time elapsed since their
entrained awakening--that is, the time since they would have gotten up
in the morning if left to their own devices, alarm clocks switched off.
While an early riser may be at his or her best in the early afternoon,
someone who sleeps late hits his or her peak much later at night.
The findings "leave no doubt that the correct determination of an
athlete's personal best performance requires consideration of circadian
phenotype, performance evaluation at different times of day, and
analysis of performance as a function of time since entrained
awakening," the researchers conclude. And the findings could come in
handy for the rest of us, too.
"Obtaining a personal best performance is on everyone's agenda, but
how to do it, now that is a different question," Facer-Childs says. One
thing now seems sure: we'd be well advised to shift our attention from
the clock on the wall to the one that's ticking inside each of us.