No Effect of Resistance Training on Autonomic Cardiovascular Control

Abstract

2399 Resistance exercise with either a small or large muscle mass causes transient doubling or tripling of arterial pressures that may severely challenge autonomic cardiac and baroreflex regulation. Potential chronic adaptations may be linked to resistance training mode, but studies describing autonomic cardiovascular adaptations to different resistance training regimens do not exist. PURPOSE: To evaluate the influence of high- and moderate-intensity resistance training on autonomic cardiovascular regulatory mechanisms. METHODS: Thirty two subjects (age 22 ± 0.6 yr) were assigned to one of three groups: resistance training for strength (RS, n = 12), resistance training for strength and endurance (RE, n = 10), or no exercise control (CON, n = 10). Subjects trained each major muscle group using 7 isotonic weight training machines 3 d/wk for 8 wk with 3 sets of 10 repetitions and 2 min rest periods (RS) or 3 sets of 15 repetitions with 30 s rest periods (RE). Resistance was progressively increased when possible. Before and after training, ECG, finger photoplethysmographic arterial pressures, and muscle sympathetic nerve activity (MSNA) were recorded with subjects supine and breathing at a set rate (0.25 Hz). Data were analyzed in both time and frequency domains. Arterial baroreflex sensitivity was assessed from cross-spectral transfer function analysis between systolic pressures and R-R intervals. RESULTS: Whole body strength increased by 22% (RS;P = 0.01) and by 21% (RE;P = 0.01). Aerobic capacity increased from 3.3 ± 0.8 to 3.7 ± 0.79 l/min (RE;P = 0.01). Muscular strength and aerobic capacity did not change for CON (P > 0.05). Heart rate and arterial pressure variability, MSNA, and arterial baroreflex sensitivity were unaffected by RS and RE. CONCLUSION: Despite significant increases in muscular strength (RS and RE) and aerobic capacity (RE), resistance training does not affect autonomic cardiovascular regulation. Supported by American Heart Association Grant 0030203N