The Effect of External and Internal Focus of Attention on Electromyography of the Lower Extremity Muscles in Different Phases of Vertical Jump

Different studies have shown the advantage of the external focus of attention using relatively simple variables. The aim of this study was to investigate the constrained action hypothesis by underlying neurophysiological mechanisms tests of the lower extremity muscle in vertical jump under the impression of Focus of Attention Types. For this purpose, 12 male professional volleyball players (mean age: 24±1.92, mean weight: 73.5±8.7) performed a vertical jump on the force plate under two conditions in a counterbalanced order: external focus and internal focus. EMG activity of the lower extremity muscle was measured during jumps by using EMG device that coupled with force plate. Paired t-test results showed height of jump under the external focus was greater than that of the internal focus, while there were no significant differences in onset and offset times of the muscles activity between attentional focus conditions (onset times:(P=0.085), offset times:(P=0.08)). Also, the results show significant increases in EMG of the lower extremity with internal focus during concentric phase (P=0.005). However, there was no significant difference in EMG of these muscles between the internal and external focus in the eccentric phase (P=0.069). These results suggest that the intermuscular of coordination are not affected by the focus conditions but the intermuscular coordination is enhanced by the external focus of attention and the external focus of attention increase develop more automation of motor control.