This study investigated the test-retest reliability and validity of the isokinetic and gravity/inertia modes of the Lido Lift (TM) and the Progressive Lifting Capacity II test (PLC II). Maximum lifting capacity tests were performed in the isokinetic and gravity/inertia modes on the Lido Lift and with the PLC II with 29 healthy male subjects. Pearson product-moment correlations were calculated to determine the test-retest reliabilities and to compare PLC II test values with isokinetic and gravity/inertia test values. The correlations for the isokinetic, gravity inertia, and the PLC II werer=.90, .82, and .91, respectively. The correlations between the isokinetic and gravity/inertia tests and the PLC II werer=.64 and .74 during the test andr=.72 and .81 during the retest. The results of this study support the reliability of both Lido Lift (TM) tests and of the PLC II, and the validity of the isokinetic and gravity/inertia tests when compared to the PLC II.