title: Resistance exercise decreases beta-endorphin immunoreactivity.
abstract: Previous research investigating the response of plasma beta-endorphins (beta-EP) to resistance exercise has resulted in equivocal findings. To examine further the effects of resistance exercise on beta-EP immunoreactivity, 10 male and 10 female college-age students participated in a series of controlled isotonic resistance exercises. The session consisted of three sets of eight repetitions at 80% of one repetition maximum (1-RM) for each of the following exercises: (1) bench press; (2) lateral pull-downs; (3) seated arm curls; and (4) military press. Blood plasma was sampled both before and after the lifting routine and beta-endorphin levels were determined by radioimmunoassay. A Students t test for paired samples indicated that mean(s.e.) plasma beta-endorphin levels after exercise (10.5(1.3) pg beta-EP ml-1) were significantly decreased as compared with pre-exercise (control) levels (16.5(1.2), P < 0.05). While the mechanism(s) contributing to the decrease in immunoreactivity is unclear, it may be the result of the synergistic effect of beta-EP clearance during rest intervals and changes in psychological states between sampling.
authors.affiliation: Department of Health and Sport Science, University of Richmond, Virginia 23173.
authors.forename: E F
authors.initials: EF
authors.lastname: Pierce
authors.forename: N W
authors.initials: NW
authors.lastname: Eastman
authors.forename: R W
authors.initials: RW
authors.lastname: McGowan
authors.forename: H
authors.initials: H
authors.lastname: Tripathi
authors.forename: W L
authors.initials: WL
authors.lastname: Dewey
authors.forename: K G
authors.initials: KG
authors.lastname: Olson
mesh_terms: D000328:Adult; D001490:Basketball / Q000502:physiology / Q000523:psychology; D015444:Exercise / Q000502:physiology / Q000523:psychology; D005260:Female; D006801:Humans; D007551:Isotonic Contraction / Q000502:physiology; D008297:Male; D011863:Radioimmunoassay; D012146:Rest / Q000502:physiology / Q000523:psychology; D014891:Weight Lifting / Q000502:physiology* / Q000523:psychology; D001615:beta-Endorphin / Q000097:blood* / Q000378:metabolism; D008083:beta-Lipotropin / Q000097:blood / Q000378:metabolism
chemical_list: D001615:beta-Endorphin; D008083:beta-Lipotropin