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Feedback Regulation Of Temporal Muscle Activation Patterns For Postural Control Before And After Peripheral Neuropathy, L Ting, D Lockhart, P Stapley, J Macpherson
Feedback Regulation Of Temporal Muscle Activation Patterns For Postural Control Before And After Peripheral Neuropathy, L Ting, D Lockhart, P Stapley, J Macpherson
Dr Paul J Stapley
Introduction: Neural mechanislllS determining temporal pattcl1ls of muscle activity during poshlral responses are not understood. Fulluwing pyridoxine inuuced somatosensory loss in cats, unset latencies of automatic poshu-al responses are delayed, and balance is impaired. We introduce a new method for correlating temporal patterns of muscle activation with task-level variahles in the context of postural responses to perturbation. Methods: We measured postmal responses to support smface tronslations before and after loss of group I afferents indnced by pyridoxine intoxication. We reconstructed temporal EMG patterns llsing a feedback loop with delays, on CoM acceleration. velocity, and displacement. Resnlts: Prior to lesion, temporal …
Muscle Synergies Of Feed-Forward Postural Adjustments During Reaching To Multi-Directional Targets In Standing, J Leonard, S Chvatal, L Ting, P Stapley
Muscle Synergies Of Feed-Forward Postural Adjustments During Reaching To Multi-Directional Targets In Standing, J Leonard, S Chvatal, L Ting, P Stapley
Dr Paul J Stapley
Standing balance can be controlled using feedback (FB) or feedforward (FF) mechanisms, depending on the nature of a postural disturbance. Unexpected disturbances of balance elicit automatic postural responses (APR) to restore body position (Horak and Macpherson 1996). Studies of APR have shown that the CNS recruits a small number of muscle synergies to simplify complex task-level goals (e.g. CoM stabilization) to produce the appropriate muscle activation patterns (Ting & McKay, 2007). Successful execution of goal-directed voluntary movements while standing requires FF programming of postural adjustments that serve to initiate movement of the body towards the target (preparatory postural adjustment, pPA) …
Independent Activation In Adjacent Lumbar Extensor Muscle Compartments, Marilee Nugent, Paul Stapley, Theodore Milner
Independent Activation In Adjacent Lumbar Extensor Muscle Compartments, Marilee Nugent, Paul Stapley, Theodore Milner
Dr Paul J Stapley
The purpose of this study was to examine compartmentalization in human lumbar spine extensors. Structure and innervation of these muscles would suggest the possibility of more segmentally specific biomechanical functions than have been found in previous studies examining muscle activation patterns during simple spine bending and twisting tasks. We selected specialized tasks to more effectively investigate the degree of independent control possible within lumbar spine extensors. We recorded surface electromyograms (SEMG) from the right posterior lumbar region during performance of two segmentally specific bellydance skills by seven novice and five trained subjects. These movements were performed at two frequencies (0.5 …
Decoupling Of Stretch Reflex And Background Muscle Activity During Anticipatory Postural Adjustments In Humans, Siddharth Vedula, Robert Kearney, Ross Wagner, Paul Stapley
Decoupling Of Stretch Reflex And Background Muscle Activity During Anticipatory Postural Adjustments In Humans, Siddharth Vedula, Robert Kearney, Ross Wagner, Paul Stapley
Dr Paul J Stapley
We studied the evolution of stretch reXexes in relation to background electromyographic (EMG) activity in the soleus muscle preceding the onset of voluntary arm raise movements. Our objective was to investigate if changes in reXex EMG and muscle activity occur simultaneously and are similarly scaled in amplitude. Ten human subjects stood with each foot on pedals able to exert short dorsiXexor pulses during stance. Subjects were asked to product consistent voluntary arm raise movements to a target upon a visual cue. In ¼ of trials, no pulse perturbations were given, but in the remaining ¾’s of all trials pulses were …
Neck Muscle Fatigue And Postural Control In Patients With Whiplash Injury, Paul Stapley, Maria Beretta, Elena Toffola, Marco Schieppati
Neck Muscle Fatigue And Postural Control In Patients With Whiplash Injury, Paul Stapley, Maria Beretta, Elena Toffola, Marco Schieppati
Dr Paul J Stapley
Objectives: To examine if patients with whiplash injury show identifiable increases in neck muscle fatigability and associated increase in postural body sway after contractions of dorsal neck muscles, and if physiotherapy treatment reduces these effects. Methods: Sway was measured during stance in 13 patients before and after 5 min of isometric dorsal neck muscle contractions and after recovery, pre- and post-physiotherapy, using a force platform. Amplitude and median frequency of neck muscle EMG were calculated during the contracting period. After each stance trial, patients gave a subjective score of sway. Results: Pre-treatment, seven patients showed EMG signs of fatigue (increases …