Cardiovascular and metabolic responses during functional electric stimulation cycling at different cadences.

Abstract

To determine the influence of pedaling cadence on cardiorespiratory responses and muscle oxygenation during functional electric stimulation (FES) leg cycling. Repeated measures. Laboratory. Nine subjects with T4 through T10 spinal cord injury (SCI) (American Spinal Injury Association grade A). FES cycling was performed at pedaling cadences of 15, 30, and 50 revolutions per minute (rpm). At each cadence, heart rate, oxygen uptake, and cardiac output were recorded during 35 minutes of cycling. Near infrared spectroscopy was used to quantify quadriceps muscle oxygenation. All pedaling cadences induced similar elevations in cardiorespiratory metabolism, compared with resting values. Higher average power output was produced at 30rpm (8.2+/-0.7W, P<.05) and 50rpm (7.9+/-0.5W, P<.05) compared with 15rpm (6.3+/-0.6W). Gross mechanical efficiency was significantly higher (P<.05) at 30 and 50rpm than at 15rpm. Quadriceps muscle oxygenation did not differ with pedaling cadences. Cardiorespiratory responses and muscle metabolism adjustments during FES leg cycling were independent of pedal cadence. FES cycling at a cadence of 50rpm may not confer any advantages over 30 or 15rpm for cardiovascular fitness promotion in persons with SCI.