Circadian rhythms and athletic performance


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- Alex Hutchinson (@sweatscience)


The latest Jockology column is posted on the Globe and Mail site (it won’t actually appear in the paper until this coming Thursday due to a schedule change, so you’re getting a sneak peak online!). The topic is circadian rhythms — how they affect physical performance, and how you can alter them. An excerpt:

[…] A 2007 study by Tunisian and French researchers found that power in an all-out 30-second cycling test was lowest at 6 a.m., then increased steadily through the day until it was about 10 per cent higher at 6 p.m., then fell steadily. A long list of earlier studies had found similar effects in back and arm strength, vertical and broad jump, and also in sports ranging from swimming to badminton, with the peak time always within a few hours of 6 p.m.

This effect may be partly a function of time awake (you’re groggy early in the day and tired later in the evening) and eating patterns (you won’t be at your best before breakfast or immediately after lunch).

But more subtle circadian rhythms, such as the daily change in core body temperature, also play a role, Dr. Sleivert says. Studies have found that body temperature rises by about 1 C between early morning and late afternoon, which may help loosen muscles and swell blood vessels in the same way a pre-exercise warm-up does… [READ THE WHOLE ARTICLE]

A related topic is how athletes deal with jet-lag, which is covered in an info-graphic that accompanies the piece (but doesn’t seem to be included online). I looked into some of the research on melatonin (the hormone that basically tells the body that it’s nighttime), and found it convincing enough that I decided to give it a try. By coincidence, I flew to London last night/this morning, so I’ll have a chance to give a try when I go to bed in a few hours. Here’s hoping for a melatonin miracle and a good night’s sleep!