CAN THE EFFICACY OF ELECTRICALLY STIMULATED PEDALING USING A COMMERCIALLY AVAILABLE ERGOMETER BE IMPROVED BY MINIMIZING THE MUSCLE STRESS-TIME INTEGRAL?

Introduction: The cardiorespiratory and muscu- lar strength benefits of functional electrical stimulation (FES) pedaling for spinal cord injury (SCI) subjects are limited because the endurance of electrically stimulated muscle is low. Methods: We tested new electrical stimulation timing patterns (Stim3, designed using a forward dynamic simulation to mini- mize the muscle stress-time integral) to determine whether SCI subjects could increase work and metabolic responses when pedaling a commercial FES ergometer. Work, rate of oxygen uptake ( _ VO2), and blood lactate data were taken from 11 sub- jects (injury level T4-T12) on repeated trials. Results: Subjects performed 11% more work pedaling with Stim3 than with exist- ing stimulation patterns (StimErg) (P ¼ 0.043). Average ( _ VO2) and blood lactate concentrations were not significantly different between Stim3 (442 ml/min, 5.9 mmol/L) and StimErg (417 ml/ min, 5.9 mmol/L). Conclusion: The increased mechanical work performed with Stim3 supports the use of patterns that mini- mize the muscle stress-time integral to prolong FES pedaling. Muscle Nerve 45: 393-402, 2012