SERUM BETA-ENDORPHIN LEVELS DURING A GRADED-EXERCISE TEST TO EXHAUSTION

  • 1 April 1987
    • journal article
    • research article
    • Vol. 19  (2) , 78-82
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 .ovrhdot.VO2max 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 .cntdot. ml-1 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 .cntdot. ml-1). 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 pheripheral .beta.-EP levels and psychological state.