circadian rhythm

There was a time, not long ago, when smoking was an ubiquitous social habit. Phone watching isn't as smelly but it seems to be just as unflattering.

We change our clocks twice a year in the U.S. because of Daylight Saving Time, and it costs the economy $434 million annually.

Here's an easy way to save over a minute on a 10km time trial - just by using light and its effects on your body physiology.

What time of the day is best to train? The key in optimizing results is to listen to your body. Our body tells us when it wants to exercise. We simply need to listen.