The Impact Of Varying Blood Flow Restriction Cuff Size On Cardiac Autonomic Modulation In Healthy Males

Blood flow restriction (BFR) training is commonly utilized to stimulate skeletal muscle hypertrophy and assist in strength gains in various populations, ranging from healthy, athletic, clinical, and elderly populations. BFR has the potential to influence the sympathetic and parasympathetic interaction by stimulating acute changes in the vascular endothelium, thereby altering cardiac autonomic modulation (CAM). Heart rate variability (HRV) is a non-invasive way to assess changes in CAM. What is unknown is the influence BFR may have on CAM due to the changes in venous and arterial pressure. PURPOSE: To determine if different BFR cuff sizes and materials alter CAM when assessed in healthy young men. METHODS: Twenty healthy males (n = 20 males, Age 25 ± 5 years, HR 66 + 11.3 bpm, SBP 125.1 + 13.4 mmHg, DBP 75.1 + 12.5 mmHg) completed a randomized, counter-balanced, cross-over design that utilized a widely-employed wide rigid (WR) cuff, along with the largest (NE) and manufacturer recommended sizes (NER) of a novel narrow-elastic cuff. HRV was measured in the supine position at baseline and amidst all three BFR cuffs at 80% arterial occlusion pressure using an elastic belt and Bluetooth monitor (Polar H7). CardioMood software was used to process HRV variables high frequency (HF), low frequency (LF), total power (TP) was assessed for frequency domain, and standard deviation of all NN intervals (SDNN) and the square root of the mean of the squares of successive R-R interval differences (RMSSD) for the time domain. The data were analyzed with SPSS using a repeated-measures ANOVA to examine differences between dependent variables, including selected time and frequency domain HRV indices. RESULTS: HRV frequency domain variables LF, HF, LF/HF, and TP, and time domain, SDNN, and RMSSD variables were not significantly altered with WR, NE, or NER cuff protocols when compared to baseline. There were no significant differences between cuff protocols. CONCLUSION: There were no changes in CAM with BFR cuff protocols in healthy young men. The lack of changes indicates that changes in the venous and arterial pressure ratio due to BFR were not great enough to offset the sympathetic and parasympathetic systems.