Heart Rate Variability Mediates Association Between Implicit Attitudes Toward Physical Activity And Exercise Frequency

Implicit attitudes toward physical activity (IAT-PA) have been shown to directly influence an individual’s PA and exercise behaviors. However, the psychophysiological mechanisms through which these automatic valuations impact actual PA levels remain unclear. Heart rate variability (HRV) is a physiological indicator of autonomic regulation and may mediate this relationship. PURPOSE: Examine whether HRV mediates the relationship between IAT-PA and self-reported exercise frequency. METHODS: Young adults (N = 314; 188 ♀, Mage = 20.5 ± 1.2 yrs; BMI = 24.4 ± 3.8 kg·m-2) completed the Single-Category Implicit Association Test (SC-IAT; higher D-scores indicating more positive attitudes), self-reported exercise frequency (number of exercise sessions·wk-1), and had HRV (root mean square of successive differences (RMSSD)), assessed using an eMotion Faros monitor during a 7-min resting state. RESULTS: D-scores were directly related to lower exercise frequency (β = -0.64, t(313) = -2.89, P = 0.0042, bootstrap 95% CI: -1.0760, -0.2034). However, mediation analyses (adjusting for gender, height, and weight) demonstrated that HRV mediated the association such that higher D-scores (IAT-PA) were associated with greater exercise frequency (β = 0.16 ± 0.08, 95% CI: 0.0022, 0.3068). CONCLUSIONS: Contrary to previous findings, our study revealed a paradoxical negative direct relationship between IAs and self-reported exercise frequency in young adults. HRV served as a crucial mediator that transformed the relationship between IAT-PA and exercise frequency from negative to positive. This suggests that the influence of IAs on exercise behaviors is not solely dependent on psychological factors but also linked to physiological states, such as autonomic regulation reflected by HRV. This physiological boost may enable individuals to better translate their positive automatic valuations into actual exercise behaviors. Thus, while IAs alone may not be sufficient to drive more frequent PA, the presence of strong autonomic regulation appears to foster a more supportive internal environment for engaging in exercise. Future research should explore the interplay between attitudes and physiological regulation to develop more holistic interventions that promote sustainable PA behaviors.