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

To determine the effects of electrical stimulation (ES) on oxygen uptake (VO(2)) kinetics and delta efficiency (DE) during gradual exercise. The hypothesis was that ES would attenuate the VO(2)-workload relation and improve DE.

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 VO(2)-power output (W) relation (deltaVO(2)/deltaW) and DE were calculated in each subject at moderate to high intensities (above the ventilatory threshold-that is, from 50-60% to 100% VO(2)max).

The mean (SEM) values for deltaVO(2)/deltaW 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 O(2)/W/min respectively and 27.7 (0.9) v 31.5 (1.4)% respectively).

ES could be used as a supplementary tool to improve two of the main determinants of endurance capacity, namely VO(2) kinetics and work efficiency.