When Is The Best Time to Workout?

If you've suspected that you exercise harder at the end of the day -- and not just when you're blowing off post-work steam -- you're right.

Research indicates that you can get your heart rate higher, and maintain it longer, during late afternoon or early evening workouts, suggesting performance can be influenced by the time of day you exercise. Not only that, but according to some studies, heart rates tend to be higher later in the day for the same level of effort as a morning workout.

While veteran running coach and exercise scientist, Roy Benson, agrees that the best performances tend to be seen in the late afternoon rather than early morning, he says dozens of factors contribute to heart rate, including the perceived level of exertion. "There are so many variables in a workout, but morning workouts can often bring a lower heart rate, even if you think you are working just as hard. Your body is simply not as relaxed and efficient, and it may not be recovered from the previous day's workout, so performance and heart rate are going to be lower."

One research study backs this up. The late Thomas Reilly and his colleagues at the Research Institute for Sport and Exercise Sciences at Liverpool John Moores University in England, found that people's maximum heart rates and sub-maximal heart rates were lower in the morning, but their perception of how hard they were working was the same in the morning as it was later in the day.

With more athletes using heart rate monitors, it can be tough to judge a workout based solely on those numbers. "Heart rate training can be a useful tool, but you have to either keep your heart rate the same or your pace the same to accurately judge performance," said Benson.

Regardless of heart rate, most coaches agree that our bodies can work harder and more efficiently later in the day. Benson has even used 5:00 a.m. trainings to "trick" the bodies of his runners into thinking that 9:00 a.m. competitions were afternoon workouts, thereby yielding better results.

Interestingly enough, it has also been noted that athletes' best performances, including world records, were typically set in the late afternoon or early evening. This leaves some wondering if more races and athletic events should be scheduled later in the day. No doubt many athletes looking for an extra edge would be in favor of this -- assuming warmer temperatures weren't a factor of course.