Differentiation of maximal from submaximal static elbow flexor efforts by measurement variability

Thirty-one young women subjects performed four maximal and four submaximal elbow flexion efforts. The strength of each effort was measured using make tests and a hand-held dynamometer. The variability of repeated maximal and submaximal tests was determined by calculating CVs for each subject. Every subject's CV was greater during submaximal than during maximal trials. Furthermore, the mean CV was significantly greater during submaximal trials than during maximal trials. No subject demonstrated a CV greater than 7.5 per cent for maximal trials, but most had CVs greater than 7.5 per cent for submaximal trials. The results suggest that for the subjects tested CVs greater than 7.5 per cent were consistent with feigned weakness. Coefficients of variation above 7.5 per cent were not, however, limited to subjects feigning weakness. Further investigations of strength variability are needed under different conditions before confident judgements can be made about patient performance.