Muscle Strength and Pressor Response

Abstract

The purpose of this study was to determine if muscle strength influences the hyperemic response to dynamic exercise. Men with low (n=8) and high (n=9) maximal forearm strength performed dynamic handgrip exercise as the same absolute workload increased in a ramp function (0.5 kg·min⁻¹). Forearm blood flow (FBF) was measured instantaneously by ultrasound Doppler and blood pressure was measured by auscultation. The pressor response to exercise was greater (P<0.05) for low strength men at workloads >1.5 kg allowing volumetric FBF (ml·min⁻¹) and vascular conductance to increase in proportion to absolute workload similar to high strength men. When FBF was expressed relative to forearm volume (ml·min⁻¹·100 ml⁻¹) the hyperemic response to exercise (slope of relative FBF vs. workload) was greater in low strength men (3.2±1.5 vs. 1.7±0.4 ml·min⁻¹·100 ml⁻¹·kg⁻¹, P<0.05) as was relative FBF at workloads >1.5 kg. However, when relative FBF was compared across relative work intensity, no difference was found between low and high strength groups. Together, these findings suggest men with low strength require a greater pressor response to match blood flow to exercise intensity as compared to high strength men.

Key words

muscle blood flow - handgrip - vascular conductance

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