Most weight lifters are probably aware of the visceral sensation they experience during a vigorous training session, which enhances strength and endurance. This feeling is caused by a change of brain chemistry from hormones produced by the adrenal glands in the abdomen. It helps promote responses to stress experienced by the body.
The adrenal glands are two triangle-shaped organs that sit directly on top of the kidneys. However, they are not related functionally to the kidneys in any way. The purpose of a tissue gland in animals is to synthesize substances for release into the bloodstream or specific body cavities. In this case, the adrenal glands release hormones that help regulate stress.
There are three main classes of adrenal hormones. Glucocorticoids include hormones like cortisol that regulate important cardiovascular, metabolic, immunologic and homeostatic functions. Catecholamines include hormones such as adrenaline, norepinephrine and dopamine that regulate stimulus and fight-or-flight mechanisms. Finally, mineralocorticoids are involved in the retention of sodium and other minerals.
When you are under stress, your brain signals the adrenal glands to produce more of the catecholamine adrenaline. Adrenaline causes a heightened sense of anxiety, blood pressure and heart rate. During exercise and weight lifting, adrenaline can also be converted into energy and burned off. This is why exercise allows tension to be released in a healthy and controlled way.
Cortisol is a catabolic hormone, meaning that it breaks larger molecules and tissue down into smaller parts. Cortisol is mainly released in response to stress, but overtraining can also elevate cortisol levels. Too much cortisol will destroy muscle tissue, contribute to fat storage and compromises the anabolic action of testosterone and growth hormones. Proper nutrition, sleep, exercise and stress buffering can counteract these effects.
Some popular books and websites claim excessive stimulation of the adrenal glands from exercise and weight lifting can cause a condition known as adrenal fatigue, which manifests as exhaustion, body aches and digestive problems, but according to Dr. Todd B. Nippoldt of the Mayo Clinic, adrenal fatigue isn't an acceptable medical diagnosis. You should consult your doctor if you begin to experience a combination of these symptoms.