Beta-endorphin and components of depression as powerful discriminators between joggers and sedentary middle-aged men

Abstract

This study identifies the relative importance of resting plasma beta-endorphin, used as a marker of perceived stress, and components of non-clinical depression that discriminate between physically active joggers and sedentary men. The profiles of joggers (n = 10) and sedentary (n = 10) middle-aged men (40-60 yr) were compared. The jogger group had been running about 20 miles per week for at least 3 yr. as expected, the joggers exhibited greater physical fitness, but lower circulating beta-endorphin (measured with the subjects at rest). The joggers also exhibited greater emotional stability (Eysenck scores), and lower depression (MMPI Scale 2 scores). In addition, the joggers had lower scores on MMPI subscales of depression: subjective depression, physical malfunctioning, mental dullness, and brooding. Multivariate discriminant function analyses showed that subjective depression, beta-endorphin, and physical malfunctioning were powerful discriminators between the jogger and sedentary groups. (1) subjective depression appeared to be the MMPI component of depression that most powerfully discriminated between joggers and sedentary middle-aged men in this study. (2) Lower beta-endorphin may be an adaptation to exercise training and was related to greater emotional stability and lower depression, especially lower subjective depression. (3) The lower beta-endorphin in the jogger group may be related to lower perceived stress in the joggers, relative to the sedentary group.