Role of muscle mass and mode of contraction in circulatory responses to exercise

Abstract

The roles of the mode of contraction (i.e., dynamic or static) and the active muscle mass as determinants of the cardiovascular responses to exercise were studied. Six healthy men performed static handgrip (SHG), dynamic handgrip (DHG), static two-knee extension (SKE), and dynamic two-knee extension (DKE) to local muscular fatigue in approximately 6 min. Increases in mean arterial pressure were similar for each mode of contraction, 29 +/- 5 and 30 +/- 3 mmHg in SHG and DHG and 56 +/- 2 and 48 +/- 2 mmHg in SKE and DKE (P greater than 0.05) but larger for KE than HG (P less than 0.001). Cardiac output increased more for dynamic than for static exercise and for each mode more for KE than HG (P less than 0.001). Systemic resistance was lower for dynamic than static exercise and fell from resting levels by approximately 1/3 during DKE. The magnitude of the pressor response was related to the active muscle mass but independent of the contraction mode. However, the mode of contraction affected the circulatory changes contributing to the pressor response. Equalization of the pressor responses was achieved by proportionately larger increases in cardiac output during dynamic exercise.

Pressor Response to Static and Dynamic Knee Extensions at Equivalent Workload in Humans

“…The different active muscle mass between the recent and present studies must have induced the different changes in the TPR in the repetitive contraction. It has been indicated that the TPR decreases from the baseline more with the increase in active muscle mass during dynamic exercise [6,7], but it does not change from the baseline during static exercise irrespective of active muscle mass [10,25,26]. In fact, Stebbins et al [10] showed that the repetitive handgrip contraction caused no change in the TPR from the baseline, which was at a level similar to that in the sustained one in the recent study.…”

“…In these studies, however, small muscle groups were used as active muscles, which were triceps surae muscles in anesthetized cats [9] and forearm muscles in conscious humans [10]. The recruited small muscle group could be the factor resulting in similar or greater pressor response in the repetitive contraction compared to the sustained contraction because the pressor response to dynamic exercise with the recruitment of large muscles is smaller than that with the recruitment of small muscles, which is due to more reduction in total peripheral resistance (TPR) with the active muscle mass [6,7]. Thus the effect of large muscle recruitments on the different pressor responses to between static and dynamic contractions remained unknown.…”

Wave reflection and central aortic pressure are increased in response to static and dynamic muscle contraction at comparable workloads

“…Previous studies attempting to compare the pressor response to dynamic and static contraction have used dynamic conditions with a lower TTI (12,21) or equated conditions on whole body oxygen uptake (3,5), which likely also results in a lower intensity in the dynamic condition due to higher muscle blood flows (35). We used the same handgrip protocol described by Stebbins et al (35), who demonstrated that peripheral diastolic, systolic and mean pressures were similar in response to static and dynamic contraction performed at 30% MVC and at the same TTI.…”

Effects of eccentric and concentric resistance training on arterial stiffness

“…It is known that the blood pressure response during exercise has relationships with exercise intensity, duration and active muscle mass. 32,33 It is also known that although ECC includes less active muscle mass than CON [34][35][36][37] its exerted muscle strength is higher than CON. 16,31 Therefore, it might be thought that the active muscle mass in CON increases more than in ECC and that the accompanying significant vasopressor response increases the load on blood vessels.…”