Simultaneous bilateral hand strength testing in a client population, Part II: Relationship to a distraction-based lifting evaluation.

OBJECTIVE To determine if passing or failing statistically-based validity criteria during a distraction-based hand strength assessment is related to test behavior during a lifting assessment. PARTICIPANTS 200 consecutive clients presenting for an FCE. METHODS The two testing protocols, one involving a hand strength assessment, the other involving an assessment of lifting capacities, were administered to assess the variability between repeated measures. RESULTS Clients failing two or more statistically-based hand strength validity criteria had significantly more variability between repeated measures in the lifting assessment, p=0.001 and 0.014 for right and left unilateral lifts, respectively, and p<0.0005 for three different bilateral lifts. CONCLUSIONS A pattern of performance related to the degree of variability in repeated measures protocols for these two distraction-based protocols is revealed. Passing or failing the hand strength assessment are each equally predictive of test outcome during the distraction-based lifting assessment. The failure of the validity criteria in these two distraction-based tests cannot be attributed to a history of surgery but, rather, is the result of abnormal test behavior.