Differentiation of gluteus medius and minimus activity in weight bearing and non-weight bearing exercises by M-mode ultrasound imaging

Abstract

BackgroundKnowledge on task-specific activity of the deep hip abductor muscles is limited and is required for determining appropriate hip abductor exercises. ObjectivesTo assess the temporal differentiation of activity of gluteus minimus and the deep and the superficial regions of gluteus medius during weight bearing and non-weight bearing exercises. DesignRepeated measures design on a single recording occasion. MethodM-mode ultrasound was used to capture activity-related muscle motion of the gluteus minimus and medius muscles in 20 healthy volunteers during weight shift, hip hitch, side-lying abduction and active leg lengthening exercises. M-mode traces were computer-processed for detecting muscle motion onsets. Mean onset differences between muscle regions and their intra-individual variability were assessed. ResultsIn contrast to side-lying abduction, the weight shift and hip hitch exercises resulted in larger onset variability between the gluteus minimus and deep gluteus medius (P < 0.001) and also between the deep and superficial regions of the gluteus medius (P < 0.05). ConclusionsWeight bearing exercises promoted a greater functional differentiation between deep and superficial hip abductor muscles.