Beta-endorphins and mood states during resistance exercise.

Research examining the relationship between beta-endorphin immunoreactivity and affect has resulted in equivocal findings. To examine this relationship further, 10 male and 10 female college-age students participated in a controlled free-weight exercise session. Blood plasma samples were procured both prior to and following the exercise bout and beta-endorphin levels were determined by immunoassay. Analysis indicated that plasma beta-endorphin levels following exercise were significantly decreased from pre-exercise levels. Pearson correlations showed no significant relationship between pre- or postexercise plasma beta-endorphins and either total mood disturbance or Profile of Mood States subscores. The data support previous failure of resistance exercise to produce an increase in beta-endorphin immunoreactivity as well as the lack of a significant relationship between affect and the beta-endorphin response to exercise.