Post-exercise cutaneous hyperaemia resulting from local exercise of an extremity

Large changes in skin blood flow occur after exercise. Most studies have concentrated on the systemic effects of vigorous exercise on skin blood flow. We were interested in the post-exercise response in the neighbourhood of focal exercise. We used a painless neuromuscular electronic stimulator to exercise the muscles of the forearm, producing flexion of the fingers. There was no change in blood pressure and only a small increase in heart rate during this exercise. We measured blood flow during a 5-min pre-exercise period and a 5-min post-exercise period at the forearm, at the dorsum of the index finger and on the pad of the index finger. We also measured values on the contralateral non-exercised extremity during exercise as well as during matched time periods in control experiments with no exercise. Exercise did elicit an increased blood flow in the post-exercise period at all three sites compared with the control experiments with no exercise and on the contralateral extremity. For example, the increase in blood flow at the finger dorsum was 2.1 +/- 0.1 ml (min 100 g)-1 after exercise compared with -0.08 +/- 0.09 ml min-1 100 g-1 during the control experiment and 0.1 +/- 0.1 ml (min 100 g)-1 on the contralateral arm (all P < 0.01). The local application of heat at the site of blood flow monitoring produced a substantial increase in the post-exercise response at the two finger locations [27.4 +/- 0.4 ml (min 100 g)-1 at the finger dorsum], but not at the arm. This is the first demonstration that highly focal exercise, unaccompanied by a systemic haemodynamic response, can elicit a post-exercise cutaneous hyperaemia. Local heating produced a large synergistic increase in the post-exercise hyperaemia at sites with arteriovenous microvascular perfusion but not at sites with primarily nutritive perfusion. These findings show that local vasoregulatory changes occur in response to exercise, even in the absence of whole-body haemodynamic and thermal change.