A MULTIVARIATE STUDY OF EXERCISE TRAINING EFFECTS ON BETA-ENDORPHIN AND EMOTIONALITY IN PSYCHOLOGICALLY NORMAL, MEDICALLY HEALTHY MEN
Abstract
The hypothesis that regular exercise training changes resting plasma concentrations of human beta-endorphin (HBE) was tested in psychologically normal, medically healthy men (N = 52, 25-63 years). The subjects were divided into six groups: four and eight month treatment (T4, n = 10; T8, n = 10), four and eight month placebo (P4, n = 5; P8, n = 6), four month jogger (J4, n = 11), and four month sedentary (S4, n = 10). T4 and T8 attended a four and eight month fitness program that involved jogging 2 miles, 3 times a week at 70% VO(,2)max. P4 and P8 had less than 50% attendance in the fitness program. J4 continued to run 5 miles, 4 times a week at 75% VO(,2)max. S4 was physically inactive. Physiological data (treadmill) at the pre and post tests were used to estimate the PFS (physical fitness score) by the method of Ismail et al. (J Appl Physiol 20: 991, 1965). Fasting, resting, early morning HBE (by radioimmunoassay) decreased (p < .01) from pre 37.85 (+OR-) 5.58 (SE) to post 24.75 (+OR-) 3.40 pg/ml in T4 and decreased (p < .001) from pre 48.45 (+OR-) 3.32 to post 31.73 (+OR-) 4.43 pg/ml in T8, while the PFS increased in both T4 (p < .002) and T8 (p < .002) from pre to post. The paired t-test showed no pre to post test differences in the control groups. In the multivariate analysis, the four month total group matrix (N = 36) was factor analyzed and HBE associated with serum calcium, high density lipoprotein cholesterol (HDL), and atherosclerotic disease risk (total cholesterol/HDL ratio) at the pretest. At the posttest, HBE associated with anxiety index (MMPI), depression (MMPI), social introversion (MMPI), and neuroticism (Eysenck). Canonical correlation analysis, with physical fitness factors and HBE in one set (p) and emotionality factors in another set (q), demonstrated that the two sets were not only related (p < .006), but also that HBE had the highest coefficient in the p set and depression had the highest coefficient in the q set. Discriminant function analysis showed that physical fitness, anxiety, depression, HBE, and neuroticism were powerful discriminators between physically active and inactive subjects. In conclusion, the present study demonstrated that there is an interaction involving physical fitness, resting beta-endorphin and emotional stability. In addition, adaptation to four and eight months to exercise training resulted in the lowering of the resting circulating beta-endorphin concentration.
Degree
Ph.D.
Subject Area
Psychobiology
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