Physiological and Mood Changes Induced by Exercise Withdrawal

Participation in regular exercise has been associated with decreased prevalence of depressed mood, whereas transient periods of reduced activity result in decreased fitness. However, most research in these areas is limited by cross-sectional designs precluding inferences about causality. This study examined the effect of systematically controlled withdrawal of high activity levels on psychological measures and physical fitness. It examines the physiological and psychological consequences of exercise deprivation using a longitudinal experimentally controlled design. It was hypothesized that decreases in fitness level would contribute to the development of negative mood following withdrawal of high activity. Regularly exercising participants (N=40) were randomly assigned either to withdrawal of high activity or continued usual high activity levels for two weeks. Exercise withdrawal resulted in increased negative mood (p0.01), and these increases were correlated with decreases in fitness level (r=0.39, p=0.014). This association became nonsignificant when statistically adjusting for baseline fitness levels and group condition (p=0.12), suggesting that fitness decline does not fully explain the psychological symptoms associated with exercise withdrawal. After a brief background to the general area of exercise withdrawal, the thesis addresses the following: (1) adverse health consequences of a sedentary lifestyle; (2) physiological and biological effects of immobility and exercise withdrawal; (3) psychological consequences of a sedentary lifestyle and exercise withdrawal; and (4) methodological approaches to systematically investigating the effects of reduced exercise levels on physiological, biological, and psychological measures.