External power output changes during prolonged cycling with electrical stimulation.
This study analysed external power output and physiologic responses in 5 individuals with paraplegia during 40 minutes of electrical stimulation leg cycle exercise. Cycling was performed on a motor-driven isokinetic ergometer that enabled precise determinations of power output. Electrical stimulation was increased to 120-140 mA within the first 5 minutes and remained constant thereafter. Power output increased to 10.7 +/- 3.0 W after 2 minutes, dropped to 5.3 +/- 1.8 W after 6 minutes and subsequently recovered to 8.2 +/- 2.2 and 6.1 +/- 2.3 W after 19.5 and 40 minutes, respectively. Oxygen consumption increased to 0.47 +/- 0.09 l/min after 6 minutes and declined during the second half of the exercise bout. Gross mechanical efficiency after 19.5 minutes was elevated compared with the value after 6 minutes. Heart rate was significantly increased at the end of the trial. The time-dependent variability of power output and physiological responses question the concept of steady state for this form of exercise.
Department of Physical Education and Rehabilitation, Faculty of Medicine, Catholic University of Louvain, Louvain-la-Neuve, Belgium. daniel.theisen@edph.ucl.ac.be
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Theisen
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Fornusek
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Raymond
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Davis
D000328:Adult; D004558:Electric Stimulation; D016552:Ergometry / Q000295:instrumentation*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010264:Paraplegia / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000503:physiopathology*