Abstract
Objectives
To investigate whether there was a gender difference in the intensity of electromyographic (EMG) activity in vastus medialis oblique (VMO) relative to vastus lateralis (VL).
Design
A cross-sectional observational study measuring EMG activity during stepping down from a step and during straight leg raise exercises.
Setting
University campus laboratory.
Participants
Two groups of healthy participants were tested, one female (mean age 23.5 years, n
=15) and one male (mean age 23.5 years, n=15).
Main outcome measures
Surface EMG activity (sampling rate 1000Hz) was recorded from VMO and VL of the dominant limb during five repetitions of a step down activity and five repetitions of a straight leg raise exercise. The average intensity of the rectified and smoothed EMG activity from each activity was normalised to that elicited in a maximal quadriceps setting exercise. The ratio of normalised VMO:VL EMG intensity levels was calculated.
Results
The median difference in the VMO:VL ratio between the groups was 0.11 [approximate 95% confidence interval (CI) −0.62 to 1.00] during step down and −0.07 (approximate 95% CI −0.26 to 0.20) during straight leg raise. Using Mann Whitney U-tests, these differences were not statistically significant (P=0.648 and 0.619, respectively).
Conclusions
This study found no gender difference in the VMO:VL EMG intensity ratio in asymptomatic participants. This suggests that the difference in incidence of patellofemoral pain syndrome between genders is not influenced by quadriceps intensity ratios, when participants are asymptomatic.
Citation
The vastus medialis oblique:vastus lateralis electromyographic intensity ratio does not differ by gender in young participants without knee pathology
Damien Bowyer, Mikaela Armstrong, John Dixon, Toby O. Smith
Physiotherapy - June 2008 (Vol. 94, Issue 2, Pages 168-173, DOI: 10.1016/j.physio.2007.08.007)