Effect of Feedback Corrective Exercise on Knee Valgus and Electromyographic Activity of Lower Limb Muscles in Single Leg Squat

Obejective: The aim of this study was assessing the effect of feedback correcting exercise in front of mirror during running on frontal plane knee and pelvic kinematic and electromyography activity of some lower extremity muscles in single leg squat (SLS). Materials & Methods: The present research was a quasi-experimental study by pre-test, post-test design and control group. 23 active and healthy female subjects participated in two experimental and control groups with mean age (21.86 +/- 2.43) years. The subjects were selected from among students of physical education in Tehran University through convenient sampling method. Experimental group contained subjects with knee valgus and pelvic drop angle more than a mean plus and one standard deviation of the population in functional SLS. Muscular activity (RMS) of gluteus maximus, Gluteus medius, rectus femoris, vastus medialis, vastus lateralis, biceps femoris and semitendinosus, angle of knee valgus and pelvic drop were registered in end of SLS before and after 8 training sessions. The variables were compared between two groups with independent t statistical test and pair sample t-test was done within each groups with significant level of 0.05 The SPSS (version 16) was applied for statistical analysis. Results: Statistical analysis before training showed no significant differences in pelvic drop between two groups (P >= 0.05), but knee valgus angle was significantly more than control group (P <= 0.05). However, most muscle activities (MVC%) were greater in experimental group, but except biceps femoris (P <= 0.05), no significant difference (P >= 0.05) has been observed in two groups. Comparing pre and post test has showed no significant difference in knee valgus of experimental group, however it decreased around 2 degrees and although MVC% decreased in all muscles, just rectuse femoris has shown significant difference (P <= 0.05). No significant difference has seen in control group in all variables (P >= 0.05). Conclusion: Findings showed poor neuromuscular control in experimental group which has been improved to some extent after training because lower muscle activity and energy consumption in specific movement with similar kinematic indicates improvement of motor control or learning. It seems that mirror corrective exercise is responsible for learning by activating mirror neurons. Also decreasing muscular activity in movements will decrease fatigue, and since many injuries are related to fatigue, it can be stated that by decreasing fatigue, injuries probably will decrease. Although, there is some evidence that this training may cause positive changes in knee valgus and lower limb neuromuscular activity, but more researches are needed to be done in order to reach certain results.