Figure 5.

Distribution of cardiac output at rest, during maximum exercise and into the recovery period. During strenuous exercise it is highly likely that muscle blood flow may reach 80% of cardiac output, whilst skin blood flow will diminish to only 5%. Also note the substantial reductions in splanchnic and renal blood flow to 3% and 2% respectively. In the recovery stage there are still requirements for muscle blood flow, but the skin assumes major importance as the major recipient of cardiac output because of its major role in heat dissipation by sweating. Note the suggested increase in respiratory blood flow during the post-race period. This diagram was adapted from Poole and Erickson [23] and used with permission. The bar graph representing the recovery period was suggested by the senior author in consultation with D. C. Poole [31].