ACTIVE FOREARM BLOOD-FLOW ADJUSTMENTS TO HANDGRIP EXERCISE IN YOUNG AND OLDER HEALTHY-MEN

1. Our purpose was to test the hypothesis that ageing impairs the acti ve muscle hyperaemia consequent to dynamic exercise in humans. 2. Elev en young (19-29 years) and eleven older (60-74 years) healthy, non-obe se men with similar chronic physical activity levels and forearm size performed two protocols of dynamic handgrip exercise: (a) brief (1 min ), incremental loads to exhaustion, and (b) sustained (8 min), submaxi mal loads. Active forearm blood flow (FBP) was measured at rest and du ring a brief period of relaxation at the end of each minute of exercis e. Arterial blood pressure was recorded to calculate active forearm va scular conductance (FVC). Sustained forearm ischaemia plus handgrip wa s used to elicit a peak forearm vasodilatatory response. 3. There were no differences in pre-exercise levels of any variable between the you ng and older men. During exercise, ratings of perceived effort, the pe ak workload attained, and the ability to sustain submaximal workloads were all similar for the two groups. 4. During brief exercise, both su bmaximal and peak levels of FBF were similar in the two groups; howeve r, the peak increases in FVC were greater in the older men. During sus tained exercise, FBF and FVC were not different in the two groups at t he lowest loads, but the increases became relatively greater in the ol der men with increasing workloads. 5. Peak levels of FBF and FVC in re sponse to the peak vasodilatatory stimulus were similar in the young a nd older men. 6. These findings fail to support the postulate that age ing results in impaired active muscle hyperaemia and vasodilatation du ring small-muscle dynamic exercise. Rather, our data indicate that the active muscle blood flow and vasodilatatory adjustments to this type of physical activity are well preserved in healthy older men. Moreover , our results suggest that neither performance of small-muscle dynamic exercise nor peak skeletal muscle vasodilatatory capacity are influen ced by the ageing process.