Background: Cervical spine muscle weakness is well demonstrated in individuals with chronic neck pain. There is a lack of literature evaluating clinically applicable means of assessing isometric cervical strength in chronic whiplash associated disorder (WAD). This study assessed the reliability of self-resisted isometric cervical strength testing using a handheld dynamometer. The relationship between strength and neck pain-related disability and kinesiophobia was also investigated.

Methods: Twenty subjects with chronic WAD performed maximum-efort isometric cervical fexion, extension, side fexion, and rotation against a hand held dynamometer. The dynamometer was held by the subject, who provided self-resistance. Subjects completed two sessions of testing on one day with two diferent examiners, and one session on a subsequent day with one of the original examiners. Subjects completed the Neck Disability Index (NDI) and Tampa Scale for Kinesiophobia (TSK) prior to the frst testing session.

Results:Intraclass correlation coefcients (ICC) for directional strength measures were fair to high (0.71–0.88 for intra-rater and 0.79–0.91 for inter-rater). Total strength (sum of all directional strengths) ICCs were high for both intrarater (ICC=0.91) and inter-rater (ICC=0.94) measures. All statistical tests for ICCs demonstrated signifcance (α

Conclusion: This study demonstrated fair to high reliability of self resisted isometric cervical strength testing in the chronic WAD population. All directional strength measures except fexion demonstrated a signifcant inverse relationship with kinesiophobia. No cervical strength measures were correlated with neck disability. These results support testing cervical strength in this manner to reliably assess change over time within individual patients. The value of such measurement requires further consideration given the lack of correlation between cervical strength and disability. Further research is required to establish normative values and enhance clinical utility.