Acute Effects of Lower Body Electromyostimulation Application with Two Different Frequencies on Isokinetic Strength and Jumping Performance

IntroductionThe possibility to generate contractile activity of a muscle with an electrical current application on the neuromuscular system has been known since the 18th century (Bax et al., 2005; Vanderthommen and Duchateau, 2007). The number of Electromyostimulation (EMS) studies has been enlarged in the last 30 years on healthy individuals and EMS has been paid attention as a new training method for athletes. Yakov Kotz has claimed that increased muscle strength (~%40) after short-term EMS training program with high frequency caused this interest. There are a lot of studies (Strauss and Domenico, 1986; Holcomb, 2005; Kraemer and Mendryk, 1982; Komi, 2008; Porcari et al., 2002; Walmsley et al., 1984; Yanagi et al., 2003) supporting or opposing these results in literature.High-frequency EMS training has increased its popularity as a method of strength training to increase maximal voluntary strength of the lower limb muscles among healthy individuals and elite athletes in the last few years (Maffiuletti et al., 2002a; Maffiuletti et al., 2002b; Malatesta et al., 2003; Marqueste et al., 2010; Taifour et al., 2013). EMS has been accepted to be an important complement in rutin strength training programs for the enhancement of athletic performance (Thorstensson et al., 1976) because it can provide more intense contraction to the stimulated muscle and thereby induce greater adaptive responses (Borniquez et al., 1993; Maffiuletti et al., 2000). LB-EMS application is an effective training method to enhance lower body power that provides intense contraction to the stimulated leg muscles and thereby induces greater adaptive responses. Local EMS application have shown positive effects on neuromuscular parameters in athletes and healthy individuals; however; there are a few multi-joint EMS studies on the effects of athletic performance and therefore, the feasibility and acceptability of this new training technology have turned out to be an important point (Kemmler et al., 2012; Kraemer and Mendryk, 1982; Kale et al., 2014; Komi, 2008, Vanderthommen and Duchateau, 2007; Porcari et al., 2002). Acute EMS applications produced the similar physiological effects as conventional aerobic exercises. Some studies have indicated that EMS training combined with aerobic exercises cause more energy consumption (%17) than aerobic exercises (Kemmler et al., 2012; Hennessy et al., 2010). Therefore it is necessary to study on the acute effects of EMS application on explosive power performances. In different EMS protocols, theoretically, partial or complete neuromuscular adaptations seem possible, but the physiological effects are different from each other. Also acute and chronic effects of EMS are still not clear. There are limited studies on the effect of a single EMS training session on isokinetic strength and jumping performance. The purpose of the present study was to investigate the acute effects of a lower body electromyostimulation (LB-EMS) bout on maximal isokinetic strength of the dominant knee extensor-flexor muscles and vertical jumping performance.Materials and MethodsIn these study vertical jump including squat jump (SJ) to assess explosive power and counter movement jump (CMJ) to assess elastic strenght performance of the lower extremity are tested. Maximal isokinetic strength test of the knee extensor-flexor muscles at different angular velocities is also an acceptable test to evaluate leg power. Heights of SJ and CMJ, and isokinetic maximal knee extensor-flexor torque values at three angular velocities were assessed to examine the acute effects of LB-EMS during static squat movement. A randomized crossover trial with moderately trained men was used to address the hypothesis of the acute effect of LB-EMS during static squat movement on jumping performance and knee extensor-flexor torque values at three angular velocities (60, 180 and 3002/s) of two different frequencies (low=30Hz and high=100Hz) with the control condition frequency (0Hz). …