Abstract

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 (ΔVo₂/ΔW) 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 ΔVo₂/ΔW 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.