Muscle strength and pressor response

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 (0.5kg·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 >1.5kg 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)·100ml(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±0.4ml·min(1) ·100ml(1)·kg(1), P<0.05) as was relative FBF at workloads >1.5kg. 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.