Reliability of manual muscle testing: A systematic review

BACKGROUND: The legitimacy of manual muscle testing (MMT) is dependent in part on the reliability of assessments obtained using the procedure. OBJECTIVE: The purpose of this review, therefore, was to consolidate findings regarding the test-retest and inter-rater reliability of MMT from studies meeting inclusion and exclusion criteria. METHODS: An electronic search of PubMed, Scopus, and CINAHL databases and a hand search were conducted to identify articles addressing the test-retest or inter-rater reliability of MMT. Data on participants, testing specifics, and findings regarding reliability were extracted. RESULTS: Of 189 unique articles identified, 9 were found to meet inclusion/exclusion criteria. The studies were highly variable in regard to the population tested, MMT procedure and scoring, and findings. Nevertheless, based on pairwise comparisons, substantial or almost perfect test-retest and inter-rater agreement was demonstrated for most muscle actions tested. CONCLUSIONS: Reliable assessments of strength may be obtained by MMT but not assumed. Further research is required to address the reliability of MMT across pathologies, muscle groups, and test procedures.