Spatial variation and inconsistency between estimates of onset of muscle activation from EMG and ultrasound.
MetadataShow full item record
Delayed onset of muscle activation can be a descriptor of impaired motor control. Activation onset can be estimated from electromyography (EMG)-registered muscle excitation and from ultrasound-registered muscle motion, which enables non-invasive measurements in deep muscles. However, in voluntary activation, EMG- and ultrasound-detected activation onsets may not correspond. To evaluate this, ten healthy men performed isometric elbow flexion at 20% to 70% of their maximal force. Utilising a multi-channel electrode transparent to ultrasound, EMG and M(otion)-mode ultrasound were recorded simultaneously over the biceps brachii muscle. The time intervals between automated and visually estimated activation onsets were correlated with the regional variation of EMG and muscle motion onset, contraction level and speed. Automated and visual onsets indicated variable time intervals between EMG- and motion onset, median (interquartile range) 96 (121) ms and 48 (72) ms, respectively. In 17% (computed analysis) or 23% (visual analysis) of trials, motion onset was detected before local EMG onset. Multi-channel EMG and M-mode ultrasound revealed regional differences in activation onset, which decreased with higher contraction speed (Spearman ??=?0.45, P?<?0.001). In voluntary activation the heterogeneous motor unit recruitment together with immediate motion transmission may explain the high variation of the time intervals between local EMG- and ultrasound-detected activation onset.
Showing items related by title, author, creator and subject.
M-Mode Ultrasound Reveals Earlier Gluteus Minimus Activity in Individuals With Chronic Hip Pain During a Step-down TaskDieterich, A.; Deshon, L.; Strauss, Geoff; McKay, J.; Pickard, Christine (2016)Study Design: Controlled laboratory study. Background: The hip abductor muscles are important hip joint stabilizers. Hip joint pain may alter muscle recruitment. Motion-mode (M-mode) ultrasound enables noninvasive ...
Dieterich, A.; Pickard, Christine; Deshon, Louise; Strauss, Geoff; Gibson, W.; Davey, Paul; McKay, J. (2015)M-mode ultrasound imaging (US) reflects motion of connective tissue within muscles. As muscle contraction is accompanied by motion of muscle tissue, M-mode US may be used to measure non-invasively the onset of deep muscle ...
Differentiation of gluteus medius and minimus activity in weight bearing and non-weight bearing exercises by M-mode ultrasound imagingDieterich, A.; Petzke, F.; Pickard, Christine; Davey, Paul; Falla, D. (2014)Background: Knowledge on task-specific activity of the deep hip abductor muscles is limited and is required for determining appropriate hip abductor exercises. Objectives: To assess the temporal differentiation of activity ...