Endorphins are responsible for the "runner's high" and for the feelings of relaxation and optimism that accompany many hard workouts — or, at least, the hot shower after your exercise is over. Behavioral factors also contribute to the emotional benefits of exercise.

noun [ C ] biology, chemistry specialized us / enˈdɔːr.fɪn / uk / enˈdɔː.fɪn / a chemical naturally, released in the brain to reduce pain, that in large amounts can make you feel relaxed or full of energy SMART Vocabulary: related words and phrases Biochemistry adipose adrenalin amino acid amylase androgen endonuclease enzymatic enzymatically

What Endorphins Do Endorphins are a group of peptides produced by your pituitary gland and central nervous system. These neurotransmitters (also sometimes thought of as hormones) act on the opiate receptors in your brain to increase feelings of pleasure and well-being and reduce pain and discomfort.