A transdisciplinary model integrating genetic, physiological, and psychological correlates of voluntary exercise

Abstract

Objective: Physical inactivity contributes to as many as 250,000 premature deaths per year (R. R. Pate et al., 1995). The authors' objective was to test a transdisciplinary model of the ways in which genetic variants, physiological factors, and psychological factors are thought to influence exercise with 64 healthy, regular exercisers.

Design: In a within-subjects design, psychological and physiological responses to exercise were compared with responses to a sedentary activity.

Main outcome measures: The authors measured affective state, perceived exertion, heart rate, and temperature change in response to moderate exercise versus sedentary activity. They also quantified genotypes on a single nucleotide polymorphism in the brain-derived neurotrophic factor (BDNF) gene.

Results and conclusions: The data show a relation between increases in positive affective states and acute exercise behavior, as opposed to a sedentary control. The BDNF gene moderated the effect of exercise on mood, heart rate, and perceived exertion. Physiological factors were, in turn, related to mood response, and mood response was a significant correlate of motivation to exercise in the future and of current exercise behavior. The model has potential as a framework for the basic study of the genetic, physiological, and psychological processes involved with voluntary exercise and as a tool for the applied examination of tailored exercise interventions and their efficacy for different subsets of individuals.

Figure 1

Transdisciplinary model of exercise behavior.

Figure 2

The effects of acute exercise on the Positive Affect subscale of the Physical Activity Affect Scale (PAAS). Positive affect increased in the acute exercise condition but not in the sedentary (control) condition. Pre = preactivity; 5 min = 5 min into the activity; 10 min = 10 min into the activity; 20 min = 20 min into the activity; post = postactivity.

Figure 3

Comparison of Physical Activity Affect Scale (PAAS) Positive Affect subscale scores by brain-derived neurotrophic factor genotype, with the more frequent genotype (G/G) individuals demonstrating significantly lower levels of positive affect during and after exercise compared with lower frequency genotype (G/A and A/A) individuals. Pre = preactivity; 5 min = 5 min into the activity; 10 min = 10 min into the activity; 20 min = 20 min into the activity; post = postactivity.

Figure 4

Comparison of Ratings of Perceived Exertion scores by brain-derived neurotrophic factor genotype, with the more frequent genotype (G/G) individuals demonstrating significantly greater levels of perceived exertion during and after exercise compared with lower frequency genotype (G/A and A/A) individuals. Pre = preactivity; 5 min = 5 min into the activity; 10 min = 10 min into the activity; 20 min = 20 min into the activity; post = postactivity.

Figure 5

Mediational model of genetic effects, physiological and psychological effects of exercise, and exercise behavior. Overall model fit: χ²(5, N = 59) = 3.94, p = .56, comparative fit index = 1.00, root-mean-square error of approximation (RMSEA) = .00, 90% confidence intervals on the RMSEA (.00, .16), Significance levels for paths: ^*p < .05, ^**p < .01. BNDF = brain-derived neurotrophic factor