Running together vs. alone: women's HRV adapts more in groups, men's more when running solo

Objectives Three objectives guided this study: (1) to test whether a brief, two-week running intervention changes heart rate variability (HRV) and mental-health parameters; (2) to examine whether running alone versus in groups differentially affects these outcomes; and (3) to assess whether participants' gender moderates these effects. Design 131 young adults with sedentary lifestyles were randomized to an individual (solo) running condition, a group-running condition, or a waitlist control, and were assessed before and after the two-week intervention. Methods Primary self-report outcomes were perceived stress, positive affect, negative affect, and depressive symptoms. Autonomic regulation was indexed by different HRV measures quantifying both parasympathetic and sympathetic aspects of autonomic function, derived from ECG recordings obtained pre- and post-intervention. Results There were no general effects of running on any HRV index, in either the solo or the group-running condition. However, HRV changes were moderated by gender and running context, as evidenced by significant TIME × GROUP × GENDER interactions in vagally mediated (parasympathetic) indices: among women, HRV increased particularly in the group-running condition, whereas among men, HRV increases were observed primarily in the solo condition. Conclusions This exploratory study indicates that HRV might not generally adapt to physical activity, but rather depends on individual or contextual factors such as gender and running context (in groups versus solo). The findings reinforce the value of HRV metrics as a tool to further support the role of physical activity in enhancing overall health and underscore the importance of tailoring physical activity interventions to individual characteristics.