Acute Psychophysiological Effects Of 4-7-8 And Nadi Shodhana Breathing: A Randomized Crossover Study.

Grounded in the Neurovisceral Integration Model (NVIM), this study examines the acute effects of two respiratory architectures-4-7-8 (exhalation-focused) and Nadi Shodhana (alternate-nostril breathing)-on stress, affect, and cardiac autonomic regulation in university students. This analyst-blinded, randomized crossover study included 34 participants (19 male, 15 female) who completed three 10-min conditions (4-7-8, Nadi Shodhana, and resting breathing) in a counterbalanced order (with a 1-week washout period between conditions). Subjective outcomes were assessed using the Perceived Stress Scale (PSS), Positive and Negative Affect Schedule (PANAS), and Visual Analog Scale (VAS). Heart rate variability (HRV) was recorded via Polar H10 (1000 Hz) and analyzed using Kubios with artifact correction. HRV parameters (SDNN, RMSSD, LF/HF) were evaluated using 3 × 2 mixed-design ANOVAs with Bonferroni correction. Significant condition × sex interactions were observed for subjective outcomes. The 4-7-8 technique was associated with reduced stress and negative affect in women, whereas Nadi Shodhana showed greater reductions in men. No significant main effects of condition were observed for conventional HRV indices. However, a significant main effect of sex was found for RMSSD (F(1, 33) = 10.19, p < 0.01, η2 = 0.24). No other HRV effects reached statistical significance. Brief respiratory interventions differentially modulate subjective emotional states in a sex-dependent manner, whereas acute autonomic changes remain limited. These findings suggest a temporal dissociation between rapid affective regulation and short-term cardiac autonomic responses, consistent with with an NVIM-based interpretation. However, the present findings do not establish specific neurovisceral mechanisms or demonstrate longer-term autonomic adaptation, which should be examined in future longitudinal studies.