Cortisol Response To Varying Levels of Intensity
It’s well known that cortisol is the stress hormone that is released in the body and can have negative impacts on our health.
Some of these negative effects include feelings of fatigue and lethargy, the greater chance of accumulation of body fat around the abdominal area, increased cravings for carbohydrates, and an increased risk for colds or other illnesses related to a weakened immune system.
In most people though, the cortisol levels released from exercise is easily dealt with and managed by the body, so it’s not something to get overly concerned with.
When one starts overtraining, however, cortisol definitely becomes more of an issue as the body is not able to keep up with the demands of the workout program.
Recently researchers decided to look how the varying intensities of exercise would impact the cortisol release in the body.
Most people assume that the greater the intensity you are working at, the more cortisol will be released. But does that mean lower intensities tend not to have much of an impact at all on cortisol?
The study was designed so that eleven healthy, physical active young men would complete an exercise test that involved progressive workload stages to determine what their peak oxygen uptake was (VO2).
Blood samples were taken at the end of each bout of exercise and cortisol concentration was determined.
The results of the study demonstrated that cortisol was significantly increased at the end of each exercise stage above normal, however the levels did not significantly different between the stages until the lactate threshold was exceeded.
This study therefore suggests that even lower intensity exercise sessions will release a cortisol response, and will be very similar until you are working at such a high intensity that you are above your lactate threshold.
The take home message to apply then is that even if you are doing ‘light’ days in your workout, thinking that this will allow your body to really recover between your higher intensity days, you may not be recovering as well as you think.
Thus, this information really helps to highlight the importance of complete rest days within your overall workout program.
Reference:
Janson, T. et al. (2008) Characterization of the cortisol response to incremental exercise in physically active young men. Acta Phsyiol Hung. Jun;95(2):219-27
