Differential Muscle Activation During Sustained Chin-Tuck Against Resistance (CTAR) Contraction is Consistent Across Different Instructional Conditions in Older Adults.

Abstract

The chin tuck against resistance (CTAR) is a popular exercise targeting suprahyoid muscles involved in swallowing. Its effectiveness presumably relies on proper execution. This study assessed the effect of different instructional strategies on neck muscle activation in older adults executing a sustained CTAR contraction. Ninety healthy individuals aged 65 to 90 years old were randomly assigned to one of three groups: video-only, video plus verbal instruction, or video with visual biofeedback using surface electromyography (sEMG). Surrogate measures of muscle recruitment and fatigue within both the suprahyoid and sternocleidomastoid muscles were compared across the three instructional groups. The sEMG amplitude measures were normalized with respect to maximal jaw opening and head rotation. Suprahyoid activity was significantly higher than sternocleidomastoid in terms of both normalized amplitude and fatigue. An analysis of variance failed to show significant differences in either sEMG measures as a function of instructional strategy, although the distribution of responses with biofeedback was significantly more clustered around the group mean (i.e. leptokurtic). The effects of sustained CTAR contractions on suprahyoid activity remain consistent across different instructional strategies, suggesting the technique is a robust one. Biofeedback does seem to improve groupwise performance predictability, however. Future studies should explore longitudinal effects to determine whether instructional strategy may affect outcomes over time.