Myofascial release induces declines in heart rate and changes to microvascular reactivity in young healthy adults

The purpose of this study was to compare physiological responses to myofascial release (MFR) and passive limb movement (PLM).

Nineteen (23 ± 2.6yrs) adults (10 men and 9 women) completed two experiments on separate days: MFR and PLM. Participation included collecting ultrasound images, blood pressure, and heart rate (HR) as well as performing a vascular occlusion test (VOT). The VOT assessed muscle tissue oxygenation (StO₂) with near-infrared spectroscopy. Experiments consisted of moving the upper limb to release subtle barriers of resistance in the muscle/fascia (MFR) and passive, assisted range of motion (PLM).

There was a significantly (p = 0.012) greater decrease in HR following MFR (-7.3 ± 5.2 BPM) than PLM (-1.3 ± 0.9 BPM). There was an equivalent change in brachial blood flow (-17.3 ± 23.0 vs. -11.9 ± 14.9 mL min^-1; p = 0.37) and vascular conductance (-19.3 ± 31.1 vs. -12.4 ± 15.3 mL min^-1 mmHg^-1; p = 0.38). Microvascular responses differed between the experiments such that MFR exhibited greater area under the curve (AUC, 1503 ± 499.1%∙s^-1 vs. 1203 ± 411.1%∙s^-1; p = 0.021) and time to maximum StO₂ (40.0 ± 8.4s vs. 35.8 ± 7.3s; p = 0.009).

As evidenced by HR, MFR induced greater parasympathetic activity than PLM. The greater AUC and time to StO_2max following MFR suggested a spillover effect to induce prolonged hyper-saturation. These results may be of interest to those investigating possible MFR-related rehabilitative benefits.