Abstract
BackgroundThe purpose of this study was to assess the between-day reliability of the electromechanical delay (EMD) of selected neck muscles during the performance of maximal isometric contractions in five different directions.MethodsTwenty-one physically active males participated in two testing sessions separated by seven to eight days. Using a custom-made fixed frame dynamometer, cervical force and surface electromyography (EMG) were recorded bilaterally from the splenius capitis, upper trapezius and sternocleidomastoid muscles during the performance of efforts in extension, flexion, left and right lateral bending, and protraction. The EMD was extracted using the Teager-Kaiser Energy Operator. Reliability indices calculated for each muscle in each testing direction were: the difference in scores between the two testing sessions and corresponding 95% confidence intervals, the standard error of measurement (SEM) and intra-class correlation coefficients (ICC).ResultsEMD values showed no evidence of systematic difference between the two testing sessions across all muscles and testing directions. The SEM for extension, flexion and lateral bending efforts ranged between 2.5 ms to 4.8 ms, indicating a good level of measurement precision. For protraction, SEM values were higher and considered to be imprecise for research and clinical purposes. ICC values for all muscles across all testing directions ranged from 0.23 to 0.79.ConclusionEMD of selected neck muscles can be measured with sufficient precision for the assessment of neck muscle function in an athletic population in the majority of directions tested.
Highlights
Concussions related to sport participation are a serious health problem, for which a multi-tiered approach has been recommended
There is scarcity in information pertaining to electromechanical delay (EMD) of the neck musculature during performance of maximal exertions, and no investigations have addressed the reproducibility of this measure in a between-day test-retest scheme
Efforts exerted in extension were the most precise, with standard error of measurement (SEM) ranging from 2.5 ms to 4.0 ms, and corresponding smallest detectable difference value (SDD) values ranging from 7.3 ms to 11.7 ms
Summary
Concussions related to sport participation are a serious health problem, for which a multi-tiered approach has been recommended. Neck strengthening exercises have been recommended as part of a comprehensive sport participation program to manage the risk for concussion [5,6,7]. This (page number not for citation purposes). A first step toward translating the predictions of these simulations to the design of evidence-based strength training programs for concussion prevention is the ability to reliably measure relevant variables of neck muscle function. The purpose of this study was to assess the between-day reliability of the electromechanical delay (EMD) of selected neck muscles during the performance of maximal isometric contractions in five different directions
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