AnyBody simulation

The lower-limb musculoskeletal model was developed using the biomechanical simulation software AnyBody version 7.4 (AnyBody Technology, Aalborg, Denmark), which has 3D motion capture dynamics. This software has undergone multiple experimental validations and demonstrates high reliability and accuracy^37,38.

A standard multibody dynamics model was constructed in the AnyBody Modeling System (AMS), and it consisted of rigid components (e.g., human bones or external objects), kinematic actuators (e.g., bodily movements), and force/torque actuators (e.g., muscles). The forces and torques during motion were simulated using multibody dynamics simulation techniques. The AMS software contains over 1000 muscle elements³⁹, which enable the detailed analysis of individual muscles, bones, and joints within the model. This analysis includes of those of forces, deformations, elastic properties of muscle tendons, antagonist muscle actions, and other biomechanically relevant characteristics^40,41. This study utilized a lower-extremity bone-muscle model based on AMS, which employs Hill-type muscle models that comprise contractile, series elastic, and parallel elastic elements. Musculoskeletal models for the BRJS and BLJS were developed (Fig. 2). Optimization algorithms addressed muscle synergy issues within the skeletal muscle model to further enhance the validity of model data. The objective was the comprehensive scientific analysis of BRJS and BLJS.

Bone-muscle models for two types of smash landing actions: (A) BRJS landing; (B) BLJS landing.