Cardiorespiratory Effects of Yogic Versus Slow Breathing in Individuals with a Spinal Cord Injury: An Exploratory Cohort Study.

Background: An intricate physiological and pathophysiological connection exists between the heart and lungs, which is especially important in individuals with spinal cord injury (SCI). While an exercise intervention may seem the best approach to leverage this relationship, the prior work has shown that, despite numerous health benefits, regular exercise training does not improve cardiorespiratory control in individuals with SCI. Breath training presents an alternative intervention that is uniquely accessible, with yogic breathing directly engaging linked fluctuations in respiration and cardiovascular control. In addition, there is evidence across a range of populations that regular yogic breathing reduces cardiovascular disease risk. It is possible that the chronic decrease in breathing frequency associated with regular yogic breathing, rather than the specific yogic breathing techniques themselves, is the primary contributor to the observed risk reduction. Methods: Therefore, in 12 individuals with traumatic SCI from C4 to T8, the authors compared Unpaced and conventional 0.083 Hz (Slow) paced breathing with various yogic breathing techniques including: (1) inspiratory-expiratory breath holds (i.e., Kumbhaka or "Box Breathing"), (2) extended exhalation (1:2 duty cycle), and (3) expiratory resistance via throat constriction (i.e., Ujjayi). Beat-to-beat heart rate and blood pressure were measured as well as end-tidal CO2 and O2 saturation were measured. Statistical analysis was performed using a one-way repeated-measures analysis of variance with post hoc pairwise t tests corrected for multiple comparisons. Results: As expected, all slow breathing patterns markedly increased respiratory sinus arrhythmia (RSA) compared with Unpaced in all ( n  = 12) individuals. More importantly, Ujjayi breathing appeared to improve ventilatory efficiency over Unpaced breathing in individuals with SCI by increasing O2 saturation (97.6% vs. 96.1%; p  = 0.042) and tended to decrease end-tidal CO2 (32 mmHg vs. 35 mmHg; p  = 0.08). While other slow breathing patterns demonstrated similar effects, only Ujjayi improved RSA while increasing heart rate and improving ventilatory efficiency. Conclusions: Hence, slow breathing per se can result in important cardiorespiratory changes, but the yogic breathing practice of Ujjayi, with glottic throat resistance, may hold the greatest promise for improving cardiorespiratory control in individuals with SCI (CTR ID No. NCT05480618).