Your body experiences a rush of hormones that start a domino effect that helps you fight strong, run fast, and feel a surge of energy to power you through your workout.
Adrenaline (also called epinephrine) is a hormone produced by the adrenal glands, which sit on top of the kidneys. The outer layer of the adrenal glands produces corticosteroids that help regulate sodium and water balance, stress responses, and metabolism (among other functions). The inner part of the adrenal glands produces epinephrine, or adrenaline. Adrenaline increases your heart and respiratory rates and blood pressure when you're in stressful situations.
An adrenaline rush happens when the adrenal glands provide a sudden increase of adrenaline to increase your heart and respiratory rate, give you a jolt of energy, and a heightened state of awareness. When a body is in a stressful situation, for example, when it is attacked by lions or running a marathon, a major jolt of energy helps the body to fight, take flight, or freeze. During exercise, an adrenaline rush helps the body endure the stress from extreme or prolonged activity. The increased heart rate adrenaline stimulates improves oxygen delivery to muscles. The National Institutes of Health (NIH) says, "As a longer term response to stress, the adrenal glands secrete cortisol to promote energy release."
Why do athletes crave an adrenaline rush? Because adrenaline helps the body perform at its best to push past limits, and go for the gold. An adrenaline rush is often accompanied by an endorphin rush (our body's feel good, pain relieving hormones) and this powerful adrenaline-endorphin hormone cocktail provides a runner's high that rewards athletes for their hard work.
Not everyone likes the way adrenaline rushes feel. In fact, it's one of the hormones you need to reduce in your body when faced chronic stress. Prolonged exposure to adrenaline and cortisol can escalate the body's inflammation response, which is linked to chronic diseases like heart disease and cancer. Exercise is an excellent way to release stress and reduce the impact that chronic exposure to stress hormones has on your health.
While an exercise-induced adrenaline rush may be good for performance, chronic exposure to stress hormones is bad for your health. The good news: Exercise helps bump up your body's ability to regulate hormones efficiently.
Sources:
National Institutes of Health
Epinephrine and Exercise
http://www.nlm.nih.gov/medlineplus/ency/anatomyvideos/000051.htm
