Relaxation in action: enhanced vagal modulation during Virabhadrasana (a standing yoga-asana) despite orthostatic demand suggests efficient regulation of effort

Introduction Classical Yoga-Āsana emphasizes not merely adoption of posture, but progressive reduction of unnecessary effort while maintaining stable engagement. However, the neurophysiological implications of effort modulation during yoga practice remain insufficiently understood. This study examined whether externally similar Yoga-Āsana performed with different effort organization may engage distinct autonomic regulatory organizations. Methods Eight experienced female yoga practitioner-teachers (median age: 58 years; median yoga experience: 19 years) participated in a within-subject exploratory study. Heart rate variability (HRV) was assessed during three 5-min conditions: free-standing, effort-reduced “yogic” Virabhadrasana (Y), and Virabhadrasana (E) performed without deliberate effort reduction. HRV indices were analysed using Friedman and Wilcoxon signed-rank tests with Holm–Bonferroni correction. Results Compared with Virabhadrasana (E), yogic Virabhadrasana (Y) demonstrated significantly increased RR interval, HF power and HF (nu), and significantly reduced LF (nu) and LF/HF ratio indicating preserved vagally mediated autonomic flexibility despite similar orthostatic demand and active postural engagement. DFAα1 values were significantly lower in the yogic condition. Discussion This study provides preliminary proof-of-concept that externally similar but effortfully different postural behaviors ( Virbhadrasana Y and E) were associated with different HRV patterns in a small group of experienced practitioners. Skilled yogic performance appears to involve efficient embodied regulation characterized by reduced regulatory burden, preserved adaptive flexibility, and relaxation within sustained action despite continued postural demand. These findings support the broader hypothesis that physiological cost depends not merely on task demands, but on the organization of regulation through which action is achieved.