Knee loads in the standard and recumbent cycling positions.

The recumbent cycling position (RCP) has become increasingly popular in recent years as a mode of exercise and rehabilitation. However, subtle, but important, differences are expected to exist between the RCP and the standard, upright cycling position (SCP). The differences are due primarily to the altered orientation of the rider's lower extremities relative to gravity. In order to determine if one cycling position may be preferential to another for certain types of rehabilitation, knee loads from a planar, inverse-dynamics model were examined. Nineteen recreational cyclists (24.6 +/- 4.2 yrs) were acclimated to recumbent cycling prior to measuring kinetics and kinematics in both a RCP and SCP (90 rpm; 250 W; max hip-to-pedal distance = 105% leg length). Significance was set at p [symbol: see text] 0.01. Lower-extremity kinematics were not different between the two positions, suggesting that muscle, ligament, and supporting structures travel through the same ranges of motion in both forms of cycling. However, the anterior/posterior forces were altered in such a way that the magnitude of the forces tending to displace the tibia anterior relative to the femur were significantly reduced in the RCP, suggesting that less load may be placed on the anterior cruciate ligament (ACL) while recumbent cycling. No changes in the tension/compression forces were observed at the knee, suggesting no differences in knee stability resulting from compressive forces between the tibia and femur. These findings indicate that the RCP may be beneficial when attempting to minimize ACL loads while utilizing cycling as an exercise and rehabilitative modality.