Biomechanical Analysis of Estimated Lower Limb Muscle Activation During Cycling at 60 rpm Cadence: A Case Study Based on OpenSim

Cycling places increasingly precise demands on cadence, pedaling angle and rider–bicycle coordination. The purpose of this study is to establish a rider–bicycle coupling model, describe the relationship between the rider and the bicycle, and characterize the predicted activation pattern of lower limb muscles during 60 rpm cadence cycling through the scaled model. A 3D motion capture system was used to record the cycling movements of a healthy male subject with 15 years of cycling experience (26 years old, height 168 cm, weight 56 kg, BMI 19.84 kg per square meter) during a cycling experiment. Pedal force information of vertical load components was acquired using plantar pressure sensors. By combining inverse kinematics and inverse dynamics, the movement trajectories and joint moments of the cycling motion were analyzed, and the activation characteristics of the major lower limb muscle groups were further examined through static optimization. The results showed that under the tested bicycle conditions, the participant model predicted that muscle groups with higher activation levels, including the hamstring, gluteus maximus, and gastrocnemius muscles, exhibited regular periodic changes. The proposed simulation framework provides a methodological reference for biomechanical analysis under the tested 60 rpm cycling condition and may provide a methodological reference for future biomechanical investigations of cycling performance and musculoskeletal function.