Stimulated muscle force assessment of the sternocleidomastoid muscle in humans

Abstract

The aim of this study was to configure a force assessment device and determine potential testing protocols for quantitative evaluation of human neck muscles. The study design consisted of non-randomized control trials, with repeated measures; data from 12 normal subjects were obtained. Several apparatuses were designed, constructed and tested, i.e. single or short trains of supramaximal stimuli were used to activate sternocleidomastoid muscles in a seated position with strain gauges (6.2% variability with double-pulse stimulations) or in a supine position with load cells (5.2% variability with similar activation). Using a final configuration, maximum elicited peak forces were 1742 ± 323 g for single-pulse and 3976 ± 484 g for double-pulse stimulations (n = 12). There were no significant differences in maximum recorded peak torques between sessions per individual. Yet, detectable muscle activities were simultaneously recorded in the contralateral sternocleidomastoid muscles. This non-invasive, quantitative assessment approach has novel value for determining treatment efficacy, disease progression, and/or relative distribution of muscle strength in patients with abnormal neck muscle function.