While it is known that Groucho running [8] significantly increases oxygen consumption (V[O.sub.2]), less information is available on the central (heart rate, HR; stroke volume, SV; cardiac output, Q) and peripheral components (arteriovenous oxygen difference, a-v[O.sub.2] diff) of steady-state V[O.sub.2].
Arteriovenous oxygen difference (a-v[O.sub.2] diff) was calculated by dividing V[O.sub.2] by Q [9].