Effect of tibia rotation on the electromyographical activity of the vastus medialis oblique and vastus lateralis longus muscles during isometric leg press

Objectives: To evaluate the electrical activity of the vastus medialis obliquus (VMO) and vastus lateralis longus (VLL) with the tibia in neutral, medial and lateral rotation on the horizontal leg press. Design: Repeated measures analysis of the effects of tibia rotation on VMO and VLL activity. Setting: Evaluation and intervention in orthopaedics and traumatology laboratory. Participants: Fifteen healthy participants, no previous musculoskeletal damage of the lower limb. Main outcome measures: Electrical activity (Root Mean Square) of the VMO and VLL was measured during submaximal isometric contractions (SIC) with the knee at 908 of flexion. The effect of tibia rotation in electrical activity of the VMO and VLL was measured. Results: VLL activity was significantly higher than VMO activity with the tibia in medial rotation ðp 1⁄4 0:03Þ: Tibia rotation did not influence the activity of the VMO muscle ðp 1⁄4 0:26Þ: VLL activity was significantly higher with medial than neutral tibia rotation ðp 1⁄4 0:005Þ: Conclusions: The results suggest that tibia rotation does not strengthen selectively the VMO muscle during isometric leg press at 908 knee flexion. q 2004 Elsevier Ltd. All rights reserved.