EMG Activity of Lower Limb Muscles During Leg Press Adopting Different Methods of Knee Stabilization

Abstract

PURPOSE: The purpose of this study was to investigate the electromyography (EMG) activity of the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF) and biceps femoris (BF) muscles in the leg press (LP) exercise using different methods to stabilize the knee, using the physioball and elastic band. METHODS: Thirteen trained women participated as subject in this study. Firstly, ten repetition maximum (RM) test and retest was applied. Secondly, the participants performed three experimental protocols in randomized design: traditional protocol (TP) - Four LP sets of 10 repetitions adopting the traditional position; (FB) Four LP sets of 10 repetitions of performed physioball between the medial condyles of the knees; (EB) Four LP sets of 10 repetitions of performed elastic band involving the lateral condyles of the knee. Three minutes of rest interval was adopted between sets. All sets were performed with 70% of 10RM loads. EMG signal was recorded for RF, VL, VM and BF.EMG data was normalized by maximal voluntary contraction. RESULTS: Higher muscle activity was noted for RF, VL and VM muscles under TP and FB compared to EB condition, respectively. No differences were observed between TP and FB between all sets and muscles. However, higher VL activity was noted under TP compared to FB and EB over the 4 sets in LP. Higher VM activity was also noted under FB compared to TP and EB, and TB compared to EB. However, no differences were noted in BF activity between sets and protocols. CONCLUSIONS:Therefore, these results showed different pattern of quadriceps activity using physioball and elastic band to stabilize the knee joint. This is an important evidence to optimize the LP prescription with the goal to increase the muscle activation.