Adding Muscle Contraction to Resonance Frequency Breathing

In this episode, Matt Bennett explores how to apply the research on HRV training through muscle contraction into personal practice.  

References for this episode. 

Fred Shaffer's work: https://youtu.be/ajwgwzn2ZUo

Sources for this summary: Vaschillo/Lehrer et al., laboratory demonstration that 0.1-Hz rhythmic skeletal muscle tension increases 0.1-Hz power in heart rate, systolic pressure, and pulse transit time and strengthens HR–BP coupling, consistent with baroreflex resonance; includes with- and without-leg-crossing conditions (N≈37). ResearchGate Shaffer, Moss, & Meehan (2022) randomized study showing that one and six contractions per minute increased multiple HRV metrics versus twelve per minute, with a ~0.10-Hz peak at six per minute. SpringerLink Meehan & Shaffer (2023) within-subjects study showing greater HR, HR max–min, and low-frequency power when adding core contraction and leg-crossing versus wrist-ankle alone at six contractions per minute. SpringerLink Frontiers in Neuroscience review describing the resonance-frequency model and noting that rhythmic skeletal muscle tension, like slow breathing, can stimulate the baroreflex at ~0.1 Hz. Frontiers Clinical and physiological studies on leg-crossing and muscle-tensing maneuvers increasing cardiac output, mean arterial pressure, and cerebral oxygenation during orthostatic stress and vasovagal reactions. Europe PMC+2Physiology Journals+2 Systematic reviews and trials on isometric handgrip training showing blood-pressure reductions with mixed HRV effects, distinct from contraction-based biofeedback. Nature+1