Edman has reported that the force-velocity relationship (FVR) departs from Hill's classic hyperbola near 0.80 of measured isometric force (J. Physiol. 404: 301-321, 1988). The purpose of this study was to investigate the biphasic nature of the FVR in the rested state and after some recovery from fatigue in the rat medial gastrocnemius muscle in situ. Force-velocity characteristics were determined prior to and during recovery from fatigue induced by intermittent stimulation at 170Hz for 100ms each second for 6 minutes. Force-velocity data were obtained for isotonic contractions with 100ms of 200Hz stimulation, including several measurements with loads above 0.80 of measured isometric force. The force-velocity data obtained in this study were fit well by a double hyperbolic equation. A departure from Hill’s classic hyperbola was found at 0.88±0.01 of measured isometric force, which is higher than the approximately 0.80 reported by Edman et al., for isolated frog fibers After 45 minutes of recovery, maximum shortening velocity was 86±2% of prefatigue, but neither curvature nor predicted isometric force were significantly different from prefatigue. The location of the departure from Hill’s classic hyperbola was not different after this recovery from the fatiguing contractions. Including an isometric point in the data set will not yield the same values for maximal velocity and the degree of curvature as would be obtained using the double hyperbola approach. Data up to 0.88 of measured isometric force can be used to fit data to the Hill equation.