Cardio and cortisol share an intimate relationship that controls how the body supplies fuel for activity. Every process of the human body requires energy. When you do cardio exercise, you cause an increase in the demand. The harder you work out, the more the need increases. In many ways, your body responds as if it were living a more hand-to-mouth lifestyle. This is no exception with its response to stress whether it is running from an attacker or trying to improve your race time.
What Is Cortisol?
To understand the relationship between cardio and cortisol, it is essential to know what cortisol is. Cortisol is a hormone produced by the adrenal glands in response to stress. From a biological perspective, stress is any change in the existing conditions. When you do a cardio workout, you are stressing your body which in turn, causes it to release cortisol. The hormone is one of three that regulates metabolism. Its function is to ensure that your body has enough energy to respond to whatever is occurring.
Stress Factor
Cortisol production acts as a defense mechanism. Stress, of course, can have negative effects. Cortisol help improve your body's resistance to stress so it can stay healthy in the face of change. During cardio workouts, the demands for energy increase with your exercise intensity. If your body detects low energy levels, another hormone will trigger the release of cortisol. Cortisol then will increase sugar metabolism for energy.
Body Adaptations
Your energy needs decline with regular exercise because your body will increase its efficiency over time. It will deliver energy and oxygen quicker to the body's cells. This efficiency may impact cortisol levels and delay a response to production of more hormone. This effect illustrates the link between aerobic exercise and cortisol. The thing to bear in mind is that the body constantly changes its responses. If you alter your cardio workouts, your body may interpret it as added stress and will release more cortisol.
Immune System Response
The negative aspect of cardio and cortisol concerns the long-term effects of stress on the body. While cortisol is essential for energy, it does so at the expense of the immune system response. Cortisol represses another chemical in the body responsible for inducing fever and releasing some white blood cells. Though it may seem contrary, the body is merely trying to allocate all sources to the immediate stress. This action explains why long-term stress and strenuous workouts without rest periods leave the body vulnerable.
References
- Franklin Institute: Renew - Stress on the Brain
- "Principles of Anatomy and Physiology"; G. Tortora et al; 2005
- Colorado State University: Glucocorticoids
- Teach PE: Long-Term Effects of Exercise
