4 to 8 p.m.: Overall exercise performance peaks. In physical activities involving strength, power, speed and stamina, this is the time zone when you’re likely to do your best, possibly because it coincides with your peak body temperature. “When your body temperature is higher, you’ll have greater lung capacity, blood flow to muscles and flexibility,” Breus says. Your hand-eye coordination and reflex reaction time are better now, too. So this is a great time for running, cycling, swimming or playing racket sports (tennis, anyone?), as well as team sports. A 2007 study from the U.K. found that soccer-specific skills, like dribbling speed, also peak in the early evening. So does performance during a cycling time trial, according to a 2005 study by the same researchers.
In addition, ratings of perceived exertion, or RPE, are at their lowest in the late afternoon and early evening hours, Rowland notes, which means you may be able to exercise harder for longer. A 2014 study from the University of North Texas in Denton found that healthy young men were able to perform exhaustive severe-intensity sessions on a stationary bicycle for 20 percent longer (until they reached the point of exhaustion) between 5 and 8 p.m. than between 6:30 and 9:30 a.m. [link]