Acute effect of percutaneous electrical stimulation of knee extensor muscles on isokinetic torque and power production performance

The aim of the present study was to examine the acute effect of a brief submaximal percutaneous electrical stimulation (PES) of the knee extensor (KE) muscles as a conditioning activity on the isokinetic peak torque (PT) and average power (AP). Eighteen male students aged 20-25 years performed maximal voluntary concentric isokinetic knee extensions at angular velocities of 60 and 180°/s in control (CON) trial (without prior PES application), followed by a PES trial after 30 min rest period. In PES trial, a conditioning submaximal (25% of the maximal voluntary isometric contraction force) isometric tetanic contraction of the KE muscles was induced by a 7 s direct PES at 100 Hz, interspersed after 3 min with testing of voluntary isokinetic performance. No significant differences in isokinetic knee extension PT and AP were observed between PES and CON trial at 60°/s. However, a significantly greater (p < 0.05) isokinetic PT (8.9%) and AP (8.2%) were observed in PES trial compared to CON trial at 180°/s. In conclusion, application of a brief high-frequency submaximal PES may enhance isokinetic strength and power of the KE at a moderate but not at a low angular velocity.