Comparison of Central Hemodynamics Between Powerlifters and Bodybuilders During Resistance Exercise

Abstract

The purpose of this investigation was to compare the heart rate, stroke volume and cardiac output between a group of five experienced powerlifters and five experienced bodybuilders. Impedance cardiography was used to assess central hemodynamics during the free-weight back squat and single-leg knee extension exercises. Each group performed sets to voluntary concentric fatigue at 50, 80 and 100 percent of the maximal resistance possible for one repetition (1 RM). Peak values of central cardiac function were determined during the eccentric and concentric phases of each contraction for each exercise. Eccentric and concentric peak heart rate significantly decreased as the percentage of 1 RM increased in both groups for both exercises, and was significantly greater for the bodybuilders than for the powerlifers during the 100 and 50 percent sets of knee extension. Eccentric and concentric peak stroke volume and cardiac output were significantly higher for the bodybuilders as compared to power-lifters at all but two percentages of 1 RM for each exercise. All eccentric values for stroke volume and cardiac output, except for the 100 percent knee extension value, were significantly greater than the concentric values. Concentric cardiac output was significantly higher for the knee extension exercise as compared to the squat at the same percentage of 1 RM for the bodybuilders. All concentric stroke volume values at the same percentage of 1 RM were greater for knee extension than for the squat exercise. Eccentric stroke volume was only greater for knee extension compared to the the squat for the bodybuilders during the 100 and 80 percent sets, and for the powerlifters during the 80 percent set. Cardiac output was not different during knee extension compared to the squat for the powerltfters except for the 100 and 50 percent eccentric sets, in which the squat was greater than knee extension. The bodybuilders showed no consistent pattern concerning cardiac output being different between the two exercises during sets at the same percentage of the 1 RM. These results indicate that the type of resistance training (powerlifting versus bodybuilding), as well as the amount of muscle mass, percentage of 1 RM lifted and phase of contraction, have a profound effect on heart rate, stroke volume and cardiac output during dynamic resistance exercises.