Medicine and science in sports and exercise
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Med Sci Sports Exerc · Dec 1987
Exercise intensity-related responses of beta-endorphin and catecholamines.
Ten men and 10 women exercised on a bicycle ergometer for 20 min at 40, 60, and 80% maximal oxygen uptake (VO2max) to determine the relationship between plasma beta-endorphin, catecholamines, and exercise intensity. Compared to rest, plasma beta-endorphins were not significantly elevated during the 40 and 60% workloads (4.8 +/- 1.0 pmol.l-1 vs 3.8 +/- 0.7 and 6.3 +/- 0.9, respectively). In contrast, the 80% exercise significantly elevated endorphins to 16.1 +/- 4.0 pmol.l-1. ⋯ The low correlation suggests a weak relationship between beta-endorphin and catecholamine responses during exercise. The results of this investigation suggest that the relationship between beta-endorphin and exercise intensity is curvilinear, with anaerobic activity producing the most significant endorphin response. It was also noted that the beta-endorphin response was not related to gender, but the amine response to exercise was gender-related, being greater for the men.