The Effect of Inactivity on Reactive Hyperaemia in the Human Calf: A Study with Strain Gauge Plethysmography

In order to study the influence of muscular inactivity on reactive hyperaemia, postischaemic blood flow was measued with strain gauge plethysmography in the calf of twenty-nine patients, who had been treated with a plaster cast for a trauma of the lower limb. The contralateral leg served as a comparison. In all but two patients postischaemic maximal flow was lower in the immobilized calf. A negative correlation existed between maximal flow and the duration of immobilization. In the course of 6 weeks after removal of the cast, the difference in maximal flow between both sides became insignificant. Venous volume and venous emptying were not different in the two limbs. The effect of inactivity on reactive hyperaemic response may be explained by an effect of inactivity on the arterioles, muscle atrophy, a decrease in capillarization and in oxidative capacity of the muscle fibres. It is concluded that inactivity and atrophy of the lower limb musculature in patients with peripheral arterial disease may be a contributing factor to the low reactive hyperaemic response in the calf of such patients.