Influence of Head-Neck Rotation on Elbow Flexor and Extensor Muscle Activity and Strength in Normal Adults

Successful rehabilitation of oropharyngeal swallowing disorders (i.e., dysphagia) requires frequent performance of head/neck exercises that primarily rely on expensive biofeedback devices, often only available in large medical centers. This directly affects treatment compliance and outcomes, and highlights the need to develop a portable and inexpensive remote monitoring system for the telerehabilitation of dysphagia. Here, we present the development and preliminarily validation of a skin-mountable sensor patch that can fit on the curvature of the submental (under the chin) area noninvasively and provide simultaneous remote monitoring of muscle activity and laryngeal movement during swallowing tasks and maneuvers. This sensor patch incorporates an optimal design that allows for the accurate recording of submental muscle activity during swallowing and is characterized by ease of use, accessibility, reusability, and cost-effectiveness. Preliminary studies on a patient with Parkinson’s disease and dysphagia, and on a healthy control participant demonstrate the feasibility and effectiveness of this system.

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Muscle activity and time to task failure differ with load compliance and target force for elbow flexor muscles

Journal of Applied Physiology ◽

10.1152/japplphysiol.00605.2010 ◽

2011 ◽

Vol 110 (1) ◽

pp. 125-136 ◽

Cited By ~ 33

Author(s):

Thorsten Rudroff ◽

Jamie N. Justice ◽

Matthew R. Holmes ◽

Stephen D. Matthews ◽

Roger M. Enoka

Keyword(s):

Muscle Activity ◽

Elbow Flexor ◽

Rating Of Perceived Exertion ◽

Isometric Contractions ◽

Time To Failure ◽

Task Failure ◽

Position Task ◽

Flexor Muscles ◽

Elbow Flexor Muscles ◽

Target Force

The primary purpose of this study was to determine the influence of load compliance on time to failure during sustained isometric contractions performed with the elbow flexor muscles at four submaximal target forces. Subjects pulled against a rigid restraint during the force task and maintained a constant elbow angle, while supporting an equivalent inertial load during the position task. Each task was sustained for as long as possible. Twenty-one healthy adults (23 ± 6 yr; 11 men) participated in the study. The maximal voluntary contraction (MVC) force was similar ( P = 0.95) before the subjects performed the force and position tasks at each of the four target forces: 20, 30, 45, and 60% of MVC force. The time to task failure was longer for the force tasks (576 ± 80 and 325 ± 70 s) than for the position tasks (299 ± 77 and 168 ± 35 s) at target forces of 20 and 30% ( P < 0.001), but was similar for the force tasks (178 ± 35 and 86 ± 14 s) and the position tasks (132 ± 29 and 87 ± 14 s) at target forces of 45 and 60% ( P > 0.19). The briefer times to failure for the position task at the lower forces were accompanied by greater rates of increase in elbow flexor muscle activity, mean arterial pressure, heart rate, and rating of perceived exertion. There was no difference in the estimates of external mechanical work at any target force. The dominant mechanisms limiting time to failure of sustained isometric contractions with the elbow flexor muscles appear to change at target forces between 30 and 45% MVC, with load compliance being a significant factor at lower forces only.

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Wrist Splint Effects on Muscle Activity and Force during a Handgrip Task

Journal of Applied Biomechanics ◽

10.1123/jab.24.3.298 ◽

2008 ◽

Vol 24 (3) ◽

pp. 298-303 ◽

Cited By ~ 4

Author(s):

Jennifer Di Domizio ◽

Jeremy P.M. Mogk ◽

Peter J. Keir

Keyword(s):

Muscle Activity ◽

Extensor Muscle ◽

External Loading ◽

Wrist Motion ◽

Wrist Extensor ◽

Custom Made ◽

Flexor Muscles ◽

Light Activity ◽

Extensor Carpi Radialis ◽

Wrist Splint

Wrist splints are commonly prescribed to limit wrist motion and provide support at night and during inactive periods but are often used in the workplace. In theory, splinting the wrist should reduce wrist extensor muscle activity by stabilizing the joint and reducing the need for co-contraction to maintain posture. Ten healthy volunteers underwent a series of 24 10-s gripping trials with surface electromyography on 6 forearm muscles. Trials were randomized between splinted and nonsplinted conditions with three wrist postures (30° flexion, neutral, and 30° extension) and four grip efforts. Custom-made Plexiglas splints were taped to the dorsum of the hand and wrist. It was found that when simply holding the dynamometer, use of a splint led to a small (<1% MVE) but significant reduction in activity for all flexor muscles and extensor carpi radialis (all activity <4% maximum). At maximal grip, extensor muscle activity was significantly increased with the splints by 7.9–23.9% MVE. These data indicate that splinting at low-to-moderate grip forces may act to support the wrist against external loading, but appears counterproductive when exerting maximal forces. Wrist bracing should be limited to periods of no to light activity and avoided during tasks that require heavy efforts.

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