Acute Handgrip Exercise Alters the Inter-arm Systolic Blood Pressure Difference in Young Males and Females

Abstract

A large inter-arm difference (IAD) in systolic blood pressure (BP) is linked to an increased likelihood of cardiovascular and peripheral vascular disease, hypertension, and premature mortality. An acute bout of aerobic exercise can alter IAD both during the activity and into post-exercise recovery. Isometric handgrip exercise (IHE) results in acute alterations in BP that differ from aerobic exercise. Further, sex differences in IHE-mediated BP exist, and cardiovagal modulation is a plausible mechanism. No prior investigations have examined IAD during IHE in males and females. PURPOSE: To characterize IAD and heart rate variability (HRV) to IHE in men and women. METHODS: On visit one, participants completed three maximal voluntary isometric contractions (MVIC) per arm using a handgrip dynamometer. During visit two, after a five-minute rest, resting HRV was assessed while each participant breathed at a rate of 12 breaths/minute. HRV analysis software was used to determine relative low- and high-frequency power for each participant. Subsequently, a series of three resting bilateral BP measures were collected and averaged (REST) utilizing an automatic oscillatory BP device. Following REST, participants maintained the handgrip dynamometer at 20% MVIC for two minutes (arm randomly assigned), at which time bilateral BP and HRV were again measured (IHE). An independent-samples t-test and repeated measures ANOVA were used to compare and track variables of interest. RESULTS: IHE resulted in increased IAD in both males and females. Males demonstrated higher IAD at REST (7±6 vs. 3±3 mmHg) and during IHE (12±9 vs. 5±4 mmHg) than their female counterparts (P<0.05), with males also expressing a lower high-frequency HRV at rest (P<0.05). CONCLUSIONS: Isometric handgrip exercise altered IAD from rest to exercise, with males displaying increased IAD during both conditions. The attenuated exercise pressor response observed in female participants may be due, in part, to a higher observed baseline of cardiovagal modulation. Future studies should address potential responses following repeated bouts of IHE, which may have important implications in those with IAD.