The results showed high correlations between SOL and GL in pretest (r = 0.803, P < 0.01) and posttest (r = 0.770, P

< 0.01). The GL and GM were highly correlated in pretest (r = 0.818, P < 0.01) and posttest (r = 0.847, P < 0.01). Furthermore, there were medium correlations between GM and SOL in pretest (r = 0.671, P < 0.05) and no significant correlations in posttest (r = 0.595, P > 0.05). Comparing the regression lines of SOL pretest versus GL pretest with SOL posttest versus GL posttest, one can see a shift to the left upper side. This can be ascribed to the decrease in GL activity and the increase in SOL activity as indicated exemplarily by one participant (Fig. 3, gray arrow). Figure 3 Inhibitors,research,lifescience,medical Correlations of the electromyography (EMG) activity of m. gastrocnemius lateralis (GL) and m. soleus (SOL) in pretest (open circles) and posttest (filled circles), respectively. The regression lines are presented for EMG activity of GL and SOL in pretest … Discussion This is the first study that demonstrated an Inhibitors,research,lifescience,medical increase in synergistic EMG activity during maximal voluntary isometric

contractions following NMES Inhibitors,research,lifescience,medical of one muscle. Due to the NMES of the GL, the EMG activity decreased to 81% in posttest. This decline was compensated by the EMG activity of SOL that increased to 112% in posttest. The force during MVC did not change significantly after NMES of the GL (Fig. 2D). Following sustained NMES of the GL, voluntary GL Entinostat price muscle activity during maximal Inhibitors,research,lifescience,medical isometric contractions was reduced (Fig. 2A). The results are in line with other studies that found decreased EMG amplitudes after high-frequency NMES (Boerio et al. 2005). The decline in EMG activity occurs due to failure of electrical propagation at the muscle fiber membrane of the GL induced by high-frequency fatigue (Cairns and Dulhunty 1995; Badier et al. 1999). Furthermore, studies using the interpolation Inhibitors,research,lifescience,medical twitch technique showed that electrical stimulation of the triceps surae lead to central fatigue (Boerio et al. 2005) accompanied by a force decline. In our studies, the force did not change significantly

(P = 0.388) after NMES of the GL. For that reason, we assume that the decline in GL in the presented study occurred more prominently due to peripheral fatigue than due to central fatigue (Badier et al. 1999). Reducing knee angle leads to reduced GM length and decreased muscle activation during MVC (Cresswell et al. 1995; Arampatzis et al. 2006). This may be due to (1) Resveratrol the “drive,” i.e., the neural outflow from spinal motor neurons, may be reduced to a shortened muscle; (2) neuromuscular transmission–propagation in a shortened muscle may be impaired, and (3) shortening a muscle may alter the electrode configuration with respect to the recording volume, thereby resulting in less myoelectric activity recorded (Cresswell et al. 1995). In our experiments, knee and ankle angle and therefore the muscle length were kept constant during pre- and posttests.