Identification of feigned strength test of the knee extensors and flexors based on the shape of the isokinetic torque curve

The purpose of this study is to assess the ability of clinicians to identify false isokinetic strength test of the knee flexors and extensors, based only on the shape of the torque curve. The concentric strength was measured bilaterally using an isokinetic dynamometer at 60 degrees /sec. Each subject performed two modes of testing: a) A Genuine strength test (GST) which consisted of five consecutive cycles of knee extension and flexion at maximal effort. b) A false strength test (FST) which consisted of five consecutive cycles of knee extensions and flexion attempting to feign pain. For each test, the torque curves were printed and presented to four judges to mark each of the tests as a GST or a FST based on the shape of the torque curves. The mean percentage of success in identifying a GST and a FST for the 4 judges was 91.9% (range = 87.5-97.5%) and 90.6% (range = 82.5-95%) respectively. In conclusion, in spite of the constraints, which were imposed on the judges, the rate of correct classifications was high.