Studies examining the effect of time of day on exercise have shown varying results and responses to exercise. In some cases, there may be a slight difference that is statistically insignificant.
One study has reported that while exercise-induced elevations of temperature were higher in the early morning than at other times of day, this increase was not statistically significant.
Exercising in the afternoon has been shown to affects anaerobic capacity. Anaerobic capacity has been shown to be significantly higher, by 26%, in the afternoon than in the morning.
In contrast, maximal aerobic exercise does not appear to be affected by time of day. In the same study examining anaerobic capacity, maximal aerobic capacity was higher in the afternoon, but this difference was not statistically significant. Another study also demonstrated that maximal aerobic capacity was not statistically different in the morning versus the afternoon.
No effect of the time of day for running has been shown on the body's anxiety responses - state anxiety, perceived exertion, heart rate, temperature and blood.
Rectal temperature and heart rate were lower in the morning than in the evening. Sweat onset occurred sooner at 08:30 h compared to 17:30 h. Time to exhaustion did not vary with time of day.