Presented at The Journal of Physiology Symposium on Exercise hyperemia, Washington, DC, USA, 2 May 2007. It was commissioned by the Editorial Board and reflects the views of the author.
Skeletal muscle vasodilatation at the onset of exercise
Article first published online: 19 SEP 2007
The Journal of Physiology
Volume 583, Issue 3, pages 825–833, September 2007
How to Cite
Clifford, P. S. (2007), Skeletal muscle vasodilatation at the onset of exercise. The Journal of Physiology, 583: 825–833. doi: 10.1113/jphysiol.2007.135673
- Issue published online: 19 SEP 2007
- Article first published online: 19 SEP 2007
- (Received 1 May 2007; accepted after revision 3 July 2007; first published online 5 July 2007)
The mechanism for exercise hyperaemia is a century old enigma. Much of the research on the topic has focused on the factors controlling skeletal muscle blood flow during steady-state dynamic exercise. It is likely that the factors which initiate the increase in blood flow are distinct from those which sustain the elevated blood flow. There is now convincing evidence that there is rapid vasodilatation following release of muscle contraction. Metabolic, neural and acetylcholine spillover mechanisms do not appear to explain the initial dilatation. Heretofore there has been only circumstantial evidence regarding the role of potassium released by skeletal muscle fibres. Studies which interrupt potassium-mediated dilatation are just emerging and are not conclusive. In addition, the latency of the vascular smooth muscle response to potassium makes it desirable to identify a mechanism that does not rely on diffusion of a vasoactive agent. Compression of the intramuscular arterioles during contraction could activate a mechanosensitive response by the vascular smooth muscle and/or endothelium. Recent in vitro and in vivo data support the notion that brief periods of mechanical compression elicit rapid vasodilatation. Thus, vascular compression could represent a feedforward mechanism for initiating skeletal muscle vasodilatation at the onset of exercise.