Figure 15.

The effects of rhythmic (1 s inflation/2 s deflation) external cuff compressions on forearm blood flow. The rhythmic inflation of an external cuff around the forearm was designed to mimic the mechanical effects of contraction. It causes a modest increase in forearm blood flow when the arm is below heart level. In contrast, when the arm is at heart level, there is little increase in blood flow. In either case, the increase in flow associated with cuff compression is very modest compared with what can be achieved with either a single contraction or more prolonged rhythmic hand gripping. This figure also shows that the effects of the muscle pump are dependent on limb position and also provides evidence that the muscle pump acting alone can generate only modest levels of blood flow. [Adapted from Tschakovsky et al. (478).]