Tibiofemoral joint forces during ergometer cycling.

Six healthy subjects pedaled on a weight-braked bicycle ergometer at different workloads, pedaling rates, saddle heights, and pedal foot positions. The subjects were filmed with a cine-film camera and pedal reaction forces were recorded from a force transducer mounted on the left pedal. Net knee moments were calculated using a dynamic model, and the tibiofemoral shear and compressive force magnitudes were calculated using a biomechanical model of the knee. During cycling at 120 W, 60 rpm, midsaddle height, and anterior pedal foot position, the mean peak tibiofemoral compressive force was 812 N [1.2 times body weight (BW)]. The maximum anteriorly directed tibiofemoral shear force was found to be low (37 N). The compressive and shear forces were significantly increased by an increased ergometer workload. The pedaling rate had no influence on the tibiofemoral force magnitudes. The stress on the ACL was low and could be further decreased by use of the anterior foot position instead of the posterior.