Objective: To describe the sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of manual muscle testing.
Design: Secondary analysis of cross-sectional strength data.
Setting: Acute rehabilitation unit.
Participants: Convenience sample of 107 consecutive qualifying rehabilitation inpatients.
Intervention: Not applicable.
Main outcome measures: Knee extension forces measured by manual muscle testing and hand-held dynamometry.
Results: The ability of manual muscle testing to detect 15, 20, 25 and 30% between-side differences and deficits in knee extension force was described. Although the specificity of manual muscle testing was acceptable (mostly > 80%), its sensitivity to differences between sides and to deficits relative to normal never exceeded 75%. Its diagnostic accuracy was never greater than 78%.
Conclusion: The results of this study cast doubt on the suitability of manual muscle testing as a screening test for strength impairments.