Acute effects of lower body electromyostimulation application with two different frequencies on isokinetic strength and jumping performance

Abstract

Electromyostimulation is commonly used for potentiation of muscle strength to supplement voluntary muscle contractions. However, the acute effects of the lower body electromyostimulation on muscle strengthening are poorly known. Fourteen moderately trained men exposed to three lower body electromyostimulation sessions in nonconsecutive days under experimental conditions (30Hz, 100Hz) and control condition (0Hz). Each subject participated in post-tests including squat jump, countermovement jump and dominant concentric knee extension-flexion isokinetic strength at 60, 180, 300°s-1.All tests performed 90 seconds after a single bout of lower body electromyostimulation with 90° static squat position for 16 seconds (4s Electromyostimulation/4s rest) at maximal tolerated current intensity. Statistical analysis have shown that there are significant increases in jump heights (p<0.05), rating perceived exertion (p?0.001) and knee flexion torques at 180 and 300°s-1 angular velocities (p<0.05) for acute electromyostimulation with two experimental conditions compared to control condition. Postactivation potentiation effect of conditioning contractions can be responsible for mechanism under these significant differences. However, there were no significant differences between low and high frequencies regarding 60°, 180°, 300°s-1 extension and 60os-1 flexion knee isokinetic torques (p>0.05) and all jump values (p>0.05). In conclusion, lower body electromyostimulation at low or high frequencies can increase explosive strength regarding high-speed flexion torques and jump height in acute phase of moderately trained men