PT on the Net Research

Best Time of Day to Exercise


One of my clients has been told that exercise in the morning is bad for you. Is this true?


While I have yet to find any research to state that there are health concerns relating to training times during the day, there are two key factors to consider when trying to determine the best time of day to train: the research and the client.

Research on Anaerobic/Aerobic Performance

While there has been a plethora of research on the best time of day to train, most of the research supports better performance in the afternoon.

Client Preference

For everyday clients, the focus needs to be more on when they can train as opposed to simply the best time to train. For example, even though aerobic based training may produce slightly better results in the afternoon, many clients may not have the availability to train at that time. Likewise, many may find the workday too exhausting and have little energy to train in the evenings. It should be remembered that circadian rhythms adapt to repetitive stimulus.

Furthermore, some clients are morning people and typically prefer to train in the mornings whereas others find the afternoons and/or evenings more congenial. With this in mind, mood before exercise does not appear to be affected by the exercise time.

What this means:

  1. When performing aerobic tests on your clients, try ensure that the diurnal patterns and circadian rhythms are consistent.
  2. The best time to train is the client’s best time to train.
  3. If the client is able to train at anytime of the day and has no preference either way, afternoons/early evening are suggested by research to hold the best performance in some criteria.


  1. Hill, D. W. (1996). Effect of time of day on aerobic power in exhaustive high-intensity exercise. Journal of Sports Medicine and Physical fitness, 36, 155-160.
  2. Hill, D. W., Borden, D. O., Darnaby, W. M., Hendricks, D. N., & Hill, C. M. (1992). Effect of time of day on aerobic and anaerobic responses to high-intensity exercise. Canadian Journal of Sport Sciences, 17, 316-319.
  3. Koltyn, K. F., Lynch, N. A., & Hill, D. W. (1998). Psychological responses to brief exhaustive cycling exercise in the morning and evening. International Journal of Sport Psychology, 29, 145-156.
  4. Lieferman, J. A., Jones, N. A., Dangelmaier, B. S., Dedrick, G. S., Burt, S. E., Swetmon, J. K., & Hill, D. W. (1995). Temporal specificity in exercise training. Medicine and Science in Sports and Exercise, 27(5), Supplement abstract 124.
  5. Rodahl, A., O'Brien, M., & Firth, P. G. (1976). Diurnal variation in performance of competitive swimmers. Journal of Sports Medicine and Physical Fitness, 16, 72-76.
  6. Scheett, T.P. Effect of training time of day on body composition, muscular strength and endurance. (2005).National Strength and Conditioning Associations Annual Meeting, Las Vegas.
  7. Sesboue, B., Bessot, N., Moussay, S., Gauthier, A., Larue, J., & Davenne, D. (2003). Diurnal variation in cycling kinematics. Medicine and Science in Sports and Exercise, 35(5), Supplement abstract 80.
  8. Torii, J., Shinkai, S., Hino, S., Kurokawa, Y., Tomita, N., Hirose, M., Watanabe, Shuichiro, Watanabe, Seiichiro, & Watanabe, T. (1992). Effect of time of day on adaptive response to a 4-week aerobic exercise program. Journal of Sports Medicine and Physical Fitness, 31, 348-352.
  9. Wang, R., Zhao, R., Shi, X., & Shi, X. (2003). Circadian influence on change in body fluid during exercise. Medicine and Science in Sports and Exercise, 35(5), Supplement abstract 1376.