It Is Not Just a Matter of Motivation: The Role of Self-Control in Promoting Physical Activity in Older Adults-A Bayesian Mediation Model

Abstract

This study aimed to understand how psychological factors affect regular exercise in older adults, hypothesising that trait self-control mediates the relationship between motivation types (intrinsic, extrinsic, and amotivation) and exercise time. In this cross-sectional study, 430 older adults (mean age = 68.8 ± 6.72) completed questionnaires regarding their perceived trait self-control, motivation towards leisure activities, and level of physical activity. A Bayesian mediation analysis was performed, controlling for demographics. We documented positive direct (c' = 0.021, 95%CI [0.001, 0.043]) and indirect (ab = 0.028, 95%CI [0.014, 0.043]) effects of intrinsic motivation on exercise, a fully mediated indirect effect of extrinsic motivation on exercise (ab = 0.027, 95%CI [0.011, 0.046]), and negative direct (c' = -0.281, 95%CI [-0.368, -0.194]) and indirect (ab = -0.161, 95%CI [-0.221, -0.105]) effects of amotivation on exercise. There was no direct association between extrinsic motivation and exercise (c' = 0.013, 95% CI [-0.013, 0.037]). In conclusion, trait self-control mediates motivation to influence exercise behaviour in older adults. Intrinsically motivated individuals resist sedentary living and show higher self-control, while extrinsically motivated ones rely on self-control and are more susceptible to non-adherence during mental fatigue. High amotivation is linked to less exercise and reduced self-control, suggesting potential non-compliance with structured exercise interventions.

Keywords: mediation analysis; motivation; older adults; physical activity; self-control; self-determination theory.

Figure 1

Flowchart of the study protocol.

Figure 2

Mediation model for motivation, trait self-control (TSC), and time spent in physical activity (TSPA). a = effect of motivation on TSC, b = effect of TSC on time spent exercising, and c′ = direct effect of motivation on time spent exercising. Indirect effect of motivation on time spent exercising through TSC is calculated as the product of a and b. The total effect of motivation on time spent exercising (denoted c) is calculated as the sum of direct and indirect effects (c = c′ + ab).

Figure 3

Schematic diagram of the Bayesian mediation analysis results. Trait self-control (TSC) significantly mediated the effect of (a) intrinsic motivation, (b) extrinsic motivation, and (c) amotivation on time spent in physical activity (TSPA). Note: * indicates a 95% credibility interval that does not contain zero.