Researchers have found a clear connection between cortisol and exercise. The amount of cortisol produced by the body is in proportion to the intensity of the exercise or stress. Intense forms of exercise, such as sprinting or lifting heavy weights, increase cortisol levels. Milder forms of exercise with a meditative component, such as tai chi, walking or yoga, keep cortisol production to a minimum. A person who exercises regularly will have a higher threshold for physical stress and will experience lower cortisol levels in reaction to intense exercise than an inactive person who attempts the same level of activity.
The connection between cortisol and exercise is clear, yet varies from individual to individual. The body releases cortisol in reaction to stressful events, whether physical, mental or emotional. When a person exercises intensely, the body perceives this as a form of stress and releases cortisol. Cortisol causes the breakdown of protein and fat and produces new glucose. This process draws on stored energy and increases bodily fuel to meet perceived physical demands.
An active individual will experience a different relationship between cortisol and exercise than someone who lives a sedentary lifestyle. A person who has been jogging daily at a moderate pace will not necessarily experience a high level of cortisol release during her daily workout. If her inactive friend goes along for the daily jog, she will very likely experience high cortisol levels doing the same workout because her body is not accustomed to the physical exertion. Likewise, if the daily jogger were to suddenly pick up her pace or significantly increase the number of miles or kilometers she jogs daily, her body could perceive this sudden intensity as a stressor and increase cortisol production.
Cortisol and exercise connections have also been observed in forms of exercise that are generally associated with lowering stress. Yoga and tai chi, and other activities that contain a mind-body-spirit component, are known to maintain cortisol levels or even lower them in some cases. These activities often involve meditation, deep breathing and visualization, which help to relax the body and reduce stress levels.
Understanding the relationship between cortisol and exercise is important because, in some cases, prolonged periods of strenuous exercise can lead to persistently high cortisol levels. Depending on the person and the situation, high cortisol levels have been observed to lead to infertility, a weakened immune system and decreased bone density. High cortisol levels are also associated with weight gain, specifically in the abdominal region. Individuals who gradually increase their fitness levels and maintain a regular program of moderate exercise generally experience balanced cortisol levels and demonstrate a healthier reaction to stress in all aspects of their lives.