Perception of Muscle Strength With and Without Biofeedback During Swallowing and Fist-Clenching Tasks

1092-5171/04/3102-0225 ABSTRACT: The purpose of this study was to investigate the accuracy of the proprioceptive system in swallowing as compared to fist clenching. The role of surface electromyography (SEMG) biofeedback in replicating motor strength was also evaluated. It was hypothesized that (a) strength of muscle contraction during swallowing would be less accurately replicated than in a fist-clenching task, (b) there would be greater variability in motor tasks attempted without the use of biofeedback, and (c) there would be greater variability in contractions of graded strength than maximal strength. The study was completed in three phases. Phase 1 participants (N = 50) were aged 20–30 years, Phase 2 participants (N = 50) were greater than 50 years, and Phase 3 participants (N = 12) were greater than 50 years and had been diagnosed with pharyngeal phase dysphagia. It was anticipated that variation in amplitude of responses would increase with age and in patients with dysphagia. SEMG activity was measured during performance of maximaland graded-strength swallowing and fist-clenching tasks. Subjects performed each task eight consecutive times, under three conditions: with biofeedback; without biofeedback; and without feedback, following a delay. An SEMG biofeedback device recorded the strength and timing of muscular activity and represented the information in analog waveform on a computer screen. Under biofeedback conditions, participants were instructed to observe the SEMG B Perception of Muscle Strength With and Without Biofeedback During Swallowing and Fist-Clenching Tasks