Does leg predomination affect the measurement of vasti muscle activity during single leg squatting? A reliability study

Does leg predomination affect measuring vasti muscle onsets during single leg squatting? A reliability study

INTRODUCTION

Although measuring vasti muscle onset may reveal whether pain relief is associated with altering this parameter during activities in subjects with patellofemoral pain syndrome (PFPS), it may be necessary to determine whether the inherent properties of the dominant leg influences the reliability of measuring VMO-VL muscle onset. The aim of the present study was to examine the effect of leg predomination on reliability testing of the VMO-VL muscle onset measurement during single leg squatting in healthy subjects.

METHODS

The onset of VMO and VL muscles of ten healthy subjects with a right dominant leg was assessed during single leg squatting. Data was collected from the muscle bellies of the VMO and VL. This procedure was performed on the both legs, during three separate single leg squats from a neutral position to a depth of approximately 30° of knee flexion. Subjects were then asked to repeat the test procedure after a minimum of a week's interval. The full wave rectified onsets of VMO and VL were then calculated.

RESULTS

There was no significant difference between the VMO-VL onset mean values of paired test of right and left knees. The ICC (intra class correlation coefficient) values during within and between sessions tests showed the poor reliability of these measurements on both knees.

CONCLUSION

The low intratester reliability of within and between sessions measurement of VMO-VL onset on the both dominant and non-dominant legs revealed that repeatability of these measurements have little accepted reliability, however similar values of these measurements indicated that leg predomination does not affect the measurements during single leg squatting.

Does Heel Height Cause Imbalance during Sit-to-Stand Task: Surface EMG Perspective

The purpose of this study was to determine whether electromyography (EMG) muscle activities around the knee differ during sit-to-stand (STS) and returning task for females wearing shoes with different heel heights. Sixteen healthy young women (age = 25.2 ± 3.9 years, body mass index = 20.8 ± 2.7 kg/m²) participated in this study. Electromyography signals were recorded from the two muscles, vastus medialis (VM) and vastus lateralis (VL) that involve in the extension of knee. The participants wore shoes with five different heights, including 4, 6, 8, 10, and 12 cm. Surface electromyography (sEMG) data were acquired during STS and stand-to-sit-returning (STSR) tasks. The data was filtered using a fourth order Butterworth (band pass) filter of 20–450 Hz frequency range. For each heel height, we extracted median frequency (MDF) and root mean square (RMS) features to measure sEMG activities between VM and VL muscles. The experimental results (based on MDF and RMS-values) indicated that there is imbalance between vasti muscles for more elevated heels. The results are also quantified with statistical measures. The study findings suggest that there would be an increased likelihood of knee imbalance and fatigue with regular usage of high heel shoes (HHS) in women.