Joint Torque Evaluation of Lower Limbs in Bicycle Pedaling

In this paper, joint torque powers of lower limbs in bicycle pedaling were investigated numerically. An approximation method of relationship between the angle of the ankle and normal force in the rotation direction of a bicycle crank while pedaling was investigatedTo calculate the joint torque power of lower limbs, a free body diagram of the motion of the lower limbs was formulated in the 2-dimensional plane. We assumed that the movements of the greater trochanters while pedaling were too small to consider. Also, bicycle shoes were supposed to be fixed to binding pedals. The free body diagram of one leg has two degrees of freedom, the crank angle and the ankle angle, when it is assumed that the greater trochanters are relatively motionless during bicycle pedaling. In previous research, the ankle angle during bicycle pedaling was obtained directly from image analysis using high-speed cameras each time the pedaling output or cadence changes. However, the relationship proposed here does not require image analysis software with high-speed cameras each time the pedaling output or cadence changes: All positions of the lower limb segments, the joint torques and the joint torque powers were calculated from the lower-limb model.The analytical system for bicycle pedaling comprised cleat-shape biaxial load cells and a program to evaluate pedaling effectiveness, joint torque and joint torque power. The plastic cleats between shoe-sole and binding pedal were replaced with biaxial load cells, which measured the biaxial-forces of right and left legs independently. Evaluations of the joint torques of the lower limbs were conducted with five male subjects to demonstrate the applicability of the proposed method.