Gas exchange kinetics following concentric-eccentric isokinetic arm and leg exercise.

PURPOSE

To evaluate the effects of exercise velocity (60, 150, 240deg∙s) and muscle mass (arm vs leg) on changes in gas exchange and arterio-venous oxygen content difference (avDO) following high-intensity concentric-eccentric isokinetic exercise.

METHODS

Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath gas exchange were recorded to determine post-exercise half-time (t) for oxygen uptake (V˙Opulm), carbon dioxide output (V˙COpulm), and ventilation (V˙).

RESULTS

Significant differences of the t values were identified between 60 and 150deg∙s. Significant differences in the t values were observed between V˙Opulm and V˙COpulm and between V˙COpulm and V˙. The time to attain the first avDO-peak showed significant differences between arm and leg exercise.

CONCLUSIONS

The present study illustrates, that V˙Opulm kinetics are distorted due to non-linear CO dynamics. Therefore, it has to be taken into account, that V˙Opulm may not be a valuable surrogate for muscular oxygen uptake kinetics in the recovery phases.