Effects of Different Heavy-Resistance Exercise Protocols on Plasma Beta-Endorphin Concentrations
Abstract
To examine the changes of plasma Beta-endorphin (beta-EP) concentrations in response to various heavy-resistance exercise protocols, eight healthy male subjects randomly performed each of six heavy-resistance exercise protocols, which consisted of identically ordered exercises carefully designed to control for the repetition maximum (RM) resistance (5 vs. 10 RM), rest period length (1 vs. 3 min), and total work (joules). Plasma Beta-EP, ammonia, whole blood lactate and serum cortisol, creatine kinase, urea, and creatinine were determined preexercise, midexercise, immediately postexercise, and at various time points after the exercise session (5 min-48 h), depending on the specific blood variable examined. Only the high total work-exercise protocol [1 min rest, 10 RM load (H10/1)] demonstrated significant increases in plasma beta-EP and serum cortisol at midexercise and 0, 5, and 15 min postexercise. Increases in lactate were observed after all protocols, but the largest increases were observed after the H10/1 protocol. Within the H10/1 protocol, lactate concentrations were correlated (r = 0.82, P < 0.05) with plasma beta-EP concentrations. Cortisol increases were significantly correlated (r = 0.84) with 24-h peak creatine kinase values. The primary finding of this investigation was that beta-EP responds differently to various heavy-resistance exercise protocols. In heavy-resistance exercise, it appears that the duration of the force production and the length of the rest periods between sets are key exercise variables that influence increases in plasma beta-EP and serum cortisol concentrations. Furthermore the H10/1 protocol's significant challenge to the acid-base status of the blood, due to marked increases in whole blood lactate, may be associated with mechanisms modulating peripheral blood concentrations of beta-EP and cortisol.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1993
- Accession Number
- ADA262252
Entities
People
- Everett A. Harman
- Joseph E. Dziados
- Louis J. Marchitelli
- N. T. Triplett
- Peter N. Frykman
- Robert Mello
- Scott E. Gordon
- Steven J. Fleck
- William J. Kraemer
Organizations
- United States Army Research Institute of Environmental Medicine