Physiological predictors of maximum treadmill walking performance in patients with intermittent claudication.

The purpose of this investigation was to identify physiological predictors of maximum treadmill walking performance (MWD) in patients with intermittent claudication. Forty-five claudicants performed a graded treadmill test to determine MWD, peak oxygen uptake, and gas exchange threshold. Calf muscle oxygenation (StO (2)) at 1 min and time to minimum StO (2) were also measured using near-infrared spectroscopy. On other occasions, peak calf blood flow, resting ankle-brachial index, and pulmonary oxygen uptake kinetics during steady-state walking were assessed. A forward stepwise multiple regression analysis was performed to determine predictors of MWD. A regression model comprising time to minimum StO (2), peak oxygen uptake, and StO (2) at 1 min explained 64% of the variation in MWD. The results suggest that cardiopulmonary fitness and the ability to match oxygen delivery to metabolic demand are important determinants of walking performance in claudicants, and that certain near-infrared spectroscopy variables might be useful in studies that evaluate the mechanisms of clinical improvement with different treatment interventions.