The effect of hip abduction on the EMG activity of vastus medialis obliquus, vastus lateralis longus and vastus lateralis obliquus in healthy subjects

Abstract

Study design: Controlled laboratory study.

Objectives: The purposes of this paper were to investigate (d) whether vastus medialis obliquus (VMO), vastus lateralis longus (VLL) and vastus lateralis obliquus (VLO) EMG activity can be influenced by hip abduction performed by healthy subjects.

Background: Some clinicians contraindicate hip abduction for patellofemoral patients (with) based on the premise that hip abduction could facilitate the VLL muscle activation leading to a VLL and VMO imbalance

Methods and measures: Twenty-one clinically healthy subjects were involved in the study, 10 women and 11 men (aged X = 23.3 +/- 2.9). The EMG signals were collected using a computerized EMG VIKING II, with 8 channels and three pairs of surface electrodes. EMG activity was obtained from MVIC knee extension at 90 degrees of flexion in a seated position and MVIC hip abduction at 0 degrees and 30 degrees with patients in side-lying position with the knee in full extension. The data were normalized in the MVIC knee extension at 50 degrees of flexion in a seated position, and were submitted to ANOVA test with subsequent application of the Bonferroni multiple comparisons analysis test. The level of significance was defined as p < or = 0.05.

Results: The VLO muscle demonstrated a similar pattern to the VMO muscle showing higher EMG activity in MVIC knee extension at 90 degrees of flexion compared with MVIC hip abduction at 0 degrees and 30 degrees of abduction for male (p < 0.0007) and MVIC hip abduction at 0 degrees of abduction for female subjects (p < 0.02196). There were no statistically significant differences in the VLL EMG activity among the three sets of exercises tested.

Conclusion: The results showed that no selective EMG activation was observed when comparison was made between the VMO, VLL and VLO muscles while performing MVIC hip abduction at 0 degrees and 30 degrees of abduction and MVIC knee extension at 90 degrees of flexion in both male and female subjects. Our findings demonstrate that hip abduction do not facilitated VLL and VLO activity in relation to the VMO, however, this study included only healthy subjects performing maximum voluntary isometric contraction contractions, therefore much remains to be discovered by future research.

Figure 1

Lateral view of the right thigh showing the origin of the obliquus portion of the vastus lateralis muscle (vastus lateralis obliquus – VLO) in the lateral intermuscular septum (LIS) and its insertion in the superior -lateral border of the patella (P). VLL – vastus lateralis longus. Bevilaqua-Grossi et al. (2004) ⁴⁶.

Figure 2

Maximum voluntary isometric contraction at 90 degrees of knee extension.

Figure 3

Maximum voluntary isometric contraction of hip abduction in neutral in side-lying position. The subjects were instructed to maintain an isometric quadriceps contraction at full knee extension while performing the task.

Figure 4

Maximum voluntary isometric contraction at 30 degrees of hip abduction in side-lying position. The subjects were instructed to maintain an isometric quadriceps contraction at full knee extension while performing the task.

Figure 5

Normalized EMG activity expressed as RMS values from healthy subjects performing MVIC knee extension at 90° of flexion, MVIC hip abduction at 0° and 30° of abduction. A) Significantly higher VMO activity for both male and female subjects performing MVIC knee extension at 90° of flexion when compared to MVIC hip abduction at 0° and 30° of abduction. B) VLL EMG activity without significant differences among the three exercises tested. C) Significantly higher VLO activity for male subjects was observed in MVIC knee extension at 90° of flexion compared with MVIC hip abduction at 0° and 30° of abduction and for female subjects performing MVIC knee extension at 90° of flexion when compared with MVIC hip abduction at 0° and 30° of abduction.