Exercise And Circulating Cortisol Levels: The Intensity Threshold Effect

[Hugh Johnson]

This study examined the influence of exercise intensity upon the cortisol response of the hypothalamic-pituitary-adrenal (HPA) axis. Specifically, we examined exercise at intensities of 40, 60, and 80% maximal oxygen uptake (VO2max) in an attempt to determine the intensity necessary to provoke an increase in circulating cortisol. Twelve active moderately trained men performed 30 min of exercise at intensities of 40, 60, and 80% of their VO2max, as well as a 30-min resting-control session involving no exercise on separate days. Confounding factors such as time of day--circadian rhythms, prior diet--activity patterns, psychological stress, and levels of exercise training were controlled. Cortisol and ACTH were assessed in blood collected immediately before (pre-) and after (post-) each experimental session. Statistical analysis involved repeated measures analysis of variance and Tukey post-hoc testing. The percent change in cortisol from pre- to post-sampling at each session was: resting-control, 40, 60, and 80% sessions (mean+/-SD) =-6.6+/-3.5%, +5.7+/-11.0%, +39.9+/-11.8%, and +83.1+/-18.5%, respectively. The 60% and 80% intensity magnitude of change was significantly greater than in the other sessions, as well as from one to another. The ACTH responses mirrored those of cortisol, but only the 80% exercise provoked a significant (p<0.05) increase pre- to post-exercise. The calculated changes in plasma volume for the resting-control, 40%, 60%, and 80% sessions were: +2.2+/-3.0%, -9.9+/-5.0%, -15.6+/-3.5%, and -17.2+/-3.3%, respectively. Collectively, the cortisol findings support the view that moderate to high intensity exercise provokes increases in circulating cortisol levels. These increases seem due to a combination of hemoconcentration and HPA axis stimulus (ACTH). In contrast, low intensity exercise (40%) does not result in significant increases in cortisol levels, but, once corrections for plasma volume reduction occurred and circadian factors were examined, low intensity exercise actually resulted in a reduction in circulating cortisol levels.

Exercise and circulating cortisol levels: the intensity threshold effect. - PubMed - NCBI

Taking walks or something might be a good idea.

 

[Makrosky]

This study examined the influence of exercise intensity upon the cortisol response of the hypothalamic-pituitary-adrenal (HPA) axis. Specifically, we examined exercise at intensities of 40, 60, and 80% maximal oxygen uptake (VO2max) in an attempt to determine the intensity necessary to provoke an increase in circulating cortisol. Twelve active moderately trained men performed 30 min of exercise at intensities of 40, 60, and 80% of their VO2max, as well as a 30-min resting-control session involving no exercise on separate days. Confounding factors such as time of day--circadian rhythms, prior diet--activity patterns, psychological stress, and levels of exercise training were controlled. Cortisol and ACTH were assessed in blood collected immediately before (pre-) and after (post-) each experimental session. Statistical analysis involved repeated measures analysis of variance and Tukey post-hoc testing. The percent change in cortisol from pre- to post-sampling at each session was: resting-control, 40, 60, and 80% sessions (mean+/-SD) =-6.6+/-3.5%, +5.7+/-11.0%, +39.9+/-11.8%, and +83.1+/-18.5%, respectively. The 60% and 80% intensity magnitude of change was significantly greater than in the other sessions, as well as from one to another. The ACTH responses mirrored those of cortisol, but only the 80% exercise provoked a significant (p<0.05) increase pre- to post-exercise. The calculated changes in plasma volume for the resting-control, 40%, 60%, and 80% sessions were: +2.2+/-3.0%, -9.9+/-5.0%, -15.6+/-3.5%, and -17.2+/-3.3%, respectively. Collectively, the cortisol findings support the view that moderate to high intensity exercise provokes increases in circulating cortisol levels. These increases seem due to a combination of hemoconcentration and HPA axis stimulus (ACTH). In contrast, low intensity exercise (40%) does not result in significant increases in cortisol levels, but, once corrections for plasma volume reduction occurred and circadian factors were examined, low intensity exercise actually resulted in a reduction in circulating cortisol levels.

Exercise and circulating cortisol levels: the intensity threshold effect. - PubMed - NCBI

Taking walks or something might be a good idea.

Really interesting! Thanks! What would be a good way to estimate where's one 40%? Besides going by intuition.

 

[jb116]

I've told many in the past, the extent of their "cardio" should be walking. You can walk all day long. A good way to lose a little excess weight too. Dr. Peat agreed too that walking is very safe and beneficial.

 

[Hugh Johnson]

Really interesting! Thanks! What would be a good way to estimate where's one 40%? Besides going by intuition.

Take walks or get some hobbies.

 

[Fractality]

When I was in Japan I walked a lot between all the various public transportation sports. Most people there do the same. I lost a few lbs (plus food serving size less there). Everyone there is slim too.

 

[Lokzo]

Interesting finding. Although, I care about the pro-androgenic properties of High Intensity exercise greater than it's effect on cortisol levels. Plus, walking does not make me feel euphoric like finishing a HIIT sprint workout.

 

[lvysaur]

Yup, I mentioned a while ago about how tracking/herding animals was a really good form of exercise. In my case, I think the goal of the activity was fun, but it's also a form of low intensity cardio.

 

[rei]

Maybe cortisol is being utilized to recycle the damaged parts of the muscles? Isn't cortisol the main hormone that achieves this?

 

[Blue Water]

How long is it elevated post-exercise? Just for 15-30 min or is it all day long?