ORIGINAL ARTICLE

Effects of electrical stimulation on VO₂ kinetics and delta efficiency in healthy young men

M Pérez¹, A Lucia¹, A Santalla², J L Chicharro³

¹ Facultad de Ciencias de la Actividad Física y el Deporte, Universidad Europea de Madrid, E-28670 Villaviciosa de Odón, Madrid, Spain
² Universidad Alfonso X El Sabio, Villanueva de la Cañada, Madrid, Spain
³ Departamento de Enfermería y Unidad de Fisiología del Ejercicio, Universidad Complutense, E-28040 Madrid, Spain

Correspondence to:
Correspondence to:
Dr Lucia, Facultad de Ciencias de la Actividad Física y el Deporte, Universidad Europea de Madrid, E-28670 Villaviciosa de Odón, Madrid, Spain;
alejandro.lucia{at}mrfs.cisa.uem.es

Objective: To determine the effects of electrical stimulation (ES) on oxygen uptake (VO₂) kinetics and delta efficiency (DE) during gradual exercise. The hypothesis was that ES would attenuate the VO₂-workload relation and improve DE.

Methods: Fifteen healthy, untrained men (mean (SD) age 22 (5) years) were selected. Ten were electrostimulated on both quadriceps muscles with a frequency of 45–60 Hz, with 12 seconds of stimulation followed by eight seconds recovery for a total of 30 minutes a day, three days a week for six weeks. The remaining five subjects were assigned to a control group. A standardised exercise test on a cycle ergometer (ramp protocol, workload increases of 20 W/min) was performed by each subject before and after the experimental period. The slope of the VO₂-power output (W) relation (VO₂/W) and DE were calculated in each subject at moderate to high intensities (above the ventilatory threshold—that is, from 50–60% to 100% VO₂max).

Results: The mean (SEM) values for VO₂/W and DE had significantly decreased and increased respectively after the six week ES programme (p<0.05; 9.8 (0.2) v 8.6 (0.5) ml O₂/W/min respectively and 27.7 (0.9) v 31.5 (1.4)% respectively).

Conclusions: ES could be used as a supplementary tool to improve two of the main determinants of endurance capacity, namely VO₂ kinetics and work efficiency.

Keywords: ventilatory threshold; ramp test; endurance; muscle fibres

Abbreviations: ES, electrical stimulation; VO₂, oxygen uptake; DE, delta efficiency; VT, ventilatory threshold

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