Cardiovascular Responses to Resistance Exercise Performed with Large and Small Muscle Mass

Prior research about the effects of the amount of exercised muscle mass upon cardiovascular responses (CVR) has neglected a potential bias related to total exercise and concentric/eccentric duration. Autonomic responses and perceived exertion (RPE) were compared in resistance exercises performed with larger and smaller muscle mass and matched for total exercise and concentric/eccentric duration. Twelve men performed 4 sets of 12 repetitions of unilateral (UNI) and bilateral (BIL) knee extensions at 70% of 12RM. Increases in CVR were always greater at the last set of BIL over UNI, as were SBP (35% vs. 23%), DBP (36% vs. 23%), HR (40% vs. 26%), RRP (90% vs 53%) and CO (55% vs 39%). No difference between protocols was found for autonomic modulation before and after exercise, but BIL induced significantly greater changes than UNI from baseline for R-R intervals (-13% vs. -7%), SDNN (-38% vs. -17%) and rMSSD (-41% vs. -21%). The rate of perceived exertion in the last set was higher in BIL than UNI (7.6±0.5 vs. 6.6±1.4 OMNI-RES; P<0.05) and did not correlate with any CVR. Thus, CVR were greater in resistance exercise performed with larger than smaller muscle mass. This information is relevant for patients with high cardiovascular risk.