"Physiological and Mood Changes Induced by Exercise Withdrawal"

Abstract

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 crosssectional designs precluding inferences about causality. The present study examined the effect of systematically controlled withdrawal of high activity levels on psychological measures and fitness. 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 (ρ<0.01), and these increases were correlated with decreases in fitness level (r=0.39, ρ=0.014). This association became non-significant when statistically adjusting for baseline fitness levels and group condition (ρ=0.12), suggesting that fitness decline does not fully explain the psychological symptoms associated with exercise withdrawal. Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. REPORT DATE INTRODUCTIONSedentary individuals are at elevated risk of all-cause and cardiovascular mortality as well as a wide range of other physical and mental disorders (Blair et al., 1996;Meyers et al., 2002). Low physical activity levels are associated with biological and psychological risk factors for cardiovascular diseases. However, most research in this area is limited by cross-sectional designs, precluding inferences about causality (Weyerer & Kupfer, 1994;Mensink, Deketh, Schuit, & Hoffmeister, 1996).Participation in exercise has been associated with improved mood and decreased stress reactivity, while transient periods of reduced activity (e.g., prolonged bed rest) result in physiological changes, among which are decreased fitness level (VO 2 max) and biological changes, such as increased markers of inflammation and coagulation (Convertino, 1997;Crandall, Engelke, Pawelczyk, Raven, & Convertino, 1994;Cruickshank, Golrlin, & Jennet, 1988). However, the naturalistic setting poses limitations to the conclusions that can be reached from these studies ...