Reliability and validity of measurements of cervical retraction strength obtained with a hand-held dynamometer.

Objectives: The purpose of this study was to describe the reliability and validity of measurements of cervical retraction strength obtained with a hand held dynamometer (HHD) from healthy adults. Background: Impaired neck muscle strength is related to neck pain, abnormal posture, and various cervical pathologies. While sophisticated devices to objectively measure neck strength exist, many are not practicable in typical orthopedic practices or have questionable validity and reliability. Methods: Forty participants were included in the analysis of neck strength using isometric testing with an HHD fixed in a cradle on a table top. The highest neck retraction force recorded in Newtons (N) for each participant, was used for data analysis. Results: Both intratester and intertester reliability were excellent as judged by intraclass correlation coefficients (ICCs) (.885 - .974) and minimal detectable change (MDC) (21.1 to 47.6 N). Validity was confirmed on the basis of expected gender and age differences (ie, men were stronger than women and younger participants were stronger than older participants). Conclusion: Fixed HHD is a reliable and valid tool for measuring isometric neck retraction strength in ostensibly healthy adults. Its value in the assessment of individuals with neck pathology awaits further examination.