Changes In Sympathovagal Balance Following High Load Resistance Exercise Compared To Blood Flow Restriction

High load resistance exercise (HL-RE) reportedly increases sympathovagal balance. However, the effects of low load blood flow restriction exercise (LL-BFRE), including cuff type, on sympathovagal balance are unclear. PURPOSE: To compare changes in sympathovagal balance following HL-RE and LL-BFRE in resistance trained (RT) men and women. METHODS: Nine RT individuals (Mean ± Standard Deviation (SD): Age: 21 ± 3 years; Men: 7; Women: 2) volunteered to participate. Heart rate signals from an electrocardiogram were collected at Rest, Immediately Post-Exercise (IP), 10-, 30-, and 45-minutes post-exercise. The HL-RE consisted of 4 sets of 8 repetitions at 70% of the one repetition maximum (1RM). LL-BFRE was performed with both a knee wrap (LL-kBFRE) and pneumatic, multi-chamber cuff (LL-pBFRE) for 4 sets of 30, 15, 15, and 15 repetitions at 30% of the 1RM. The elastic knee wraps during LL-kBFRE were wrapped on the upper arms at a 7 out of 10 rate of perceived pressure. During LL-pBFRE, the pneumatic cuff was inflated to 40% of estimated arterial occlusion pressure. Following data collection, power spectral analysis was used to generate measures of heart rate variability (HRV) in the frequency domain including low frequency (LF) power and high frequency (HF) power. The ratio of LF power to HF power (LF/HF) was calculated and used as an index of sympathovagal balance. Prior to analysis, the LF and HF power and LF/HF were logarithmically (ln) transformed. A two-way repeated measures ANOVA was used to examine the effect of condition (HL-RE, LL-kBFRE, LL-pBFRE) across time (Rest, IP, 10, 30 and 45 minutes) on the lnLF/HF. Significant (p ≤ 0.05) effects were analyzed using pairwise comparisons with a Sidak correction factor. RESULTS: There was no significant (p > 0.05) condition by time interaction. However, there was a significant main effect of time (F = 6.44, p ≤ 0.001, ηp2 = 0.45) for lnLF/HF such that it was increased at 30 minutes (0.92 ± 0.07%) and 45 minutes (0.90 ± 0.05%) compared to Rest (0.85 ± 0.06%) across all conditions. CONCLUSION: These data suggest that there are no differences in sympathovagal balance following HL-RE and LL-BFRE, including cuff type. However, sympathovagal balance is increased for at least 45 minutes post-exercise. Notably, this increase also appears to be delayed and manifests at 30 minutes post-exercise.