Abstract

Nine untrained college age males completed a graded exercise protocol to maximal capacity on a bicycle ergometer to determine if there was a relationship between intensity of exercise and serum beta-endorphin (beta-EP) levels. Subjects fasted for 12 h and abstained from physical activity at least 24 h prior to testing. Subjects completed the Multiple Affect Adjective Check List prior to and following exercise to ascertain if psychological state would be associated with beta-EP levels. The initial workload was 150 kilopond meters and was increased 150 kilopond meters every 3 min until V02max or leg fatigue occurred. Expired gases were continuously analyzed, and a venous blood sample was drawn from an indwelling catheter during the final 30 s of each stage and 5-min post-exercise. Beta-EP levels were determined from serum using a radioimmunoassay technique and corrected for cross-reactivity with beta-lipotropin using affinity chromatography. Resting beta-EP levels were 25.3 +/- 4.1 pg.ml and did not demonstrate significant changes during any stage of exercise. A correlation analysis (r = 0.30) revealed no significant relationship between exercise intensity and beta-EP levels. Following exercise, beta-EP levels were significantly increased compared to resting values (38.8 +/- 4.8 pg.ml). In addition, psychological state was unaffected by exercise despite significant increases in recovery beta-EP levels. These data support previous studies reporting increases in beta-EP levels following exercise, but do not indicate a relationship between intensity of exercise and beta-EP levels during graded exercise or peripheral beta-EP levels and psychological state. Verf.-Referat