The effect of limb position, exercise mode and contraction type on overall activity of VMO and VL

ObjectiveThis study aimed to investigate the effect of various exercise parameters on VMO and VL EMG activity levels, along with the effect of gender on these parameters.DesignWithin-subjects repeated measures.SettingUniversity Biomechanics Laboratory.ParticipantsTwenty male and 23 female healthy asymptomatic individuals.Outcome measureSurface EMG of VMO and VL (RMS). This was measured during single- and multiple-joint quadriceps exercises in three hip positions (internal, external and neutral rotation), lifting a normalised load at a constant angular velocity.ResultsNo difference in overall activity (RMS) for VMO and VL (p=0.78p=0.78) between males and females for modes of contraction, hip positions or exercise was found. Analysis by factorial ANOVA showed the main effects of muscle (p=0.98p=0.98), hip position (p=0.33p=0.33) and exercise type (p=0.79p=0.79) did not have a significant effect on EMG activity, the nature of contraction (eccentric or concentric) had a significant effect (p<0.001p<0.001) on EMG activity. There were no significant interactions (p>0.05p>0.05).ConclusionThe study undertaken found that the relative difference in overall activity between VMO and VL was not influenced by gender, hip position, type of contraction or mode of exercise. It is unlikely that those exercises aimed at preferentially increasing VMO activity are likely to be successful in asymptomatic individuals. Clinicians treating patients with PFP should consider these findings when selecting exercises which could preferentially activate VMO.