Musculoskeletal models based on multibody dynamics have been widely applied in human biomechanics research; however, conventional one-dimensional (1D) muscle models are limited in their ability to represent realistic muscle geometry and fiber architecture, resulting in restricted biomechanical predictions. Although three-dimensional (3D) finite element (FE) muscle models can provide more detailed mechanical information, high computational cost limits their application at the whole lower-limb scale. To address these limitations, this study develops a unilateral lower-limb musculoskeletal model with hybrid muscles based on the TLEM2.0 database, in which the soleus-gastrocnemius muscle group was represented using 3D FE models, while the remaining muscles were modeled using 1D Hill-type formulations. By coupling FE analysis with muscle recruitment optimization, muscle activation patterns of the right lower limb during the stance phase of level walking were obtained. Model predictions were validated against in vivo knee joint reaction forces and surface electromyography (sEMG) data. The results demonstrated good agreement between the predicted and experimentally measured knee joint reaction forces, and the predicted force patterns of the medial and lateral gastrocnemius muscles corresponded well with sEMG trends. In addition, the model enabled detailed observation of muscle deformation as well as internal tensile stress and strain distributions in the 3D muscles during gait. This hybrid musculoskeletal modeling framework achieves a balance between computational efficiency and biomechanical fidelity, providing an effective platform for investigating lower-limb muscle biomechanics.
Obesity is a chronic metabolic disease driven by multiple factors such as genetic susceptibility, environmental factors, and neuroendocrine system disorders. In recent years, the prevalence of obesity in China has been increasing year by year, and a series of obesity-induced diseases are a serious threat to public health. Glucagon-like peptide-1 receptor agonists, as a representative of the new weight loss drugs, have shown a therapeutic effect close to that of weight-loss metabolic surgery in clinical trials by targeting central appetite and metabolism and other synergistic effects, but they still face key problems such as significant differences in individual efficacy, limited evidence of the safety of long-term treatment, and regaining body weight after discontinuation of the drug. The mechanism of action and clinical evidence of several obesity drugs approved and listed in China are summarized, and the progress and challenges of obesity drug therapy in China in combination with recent advances in the development of multi-target agents internationally are discussed, with a view to providing a scientific basis for the clinical drug management of obesity and providing ideas for the research and development of obesity drugs in China as well as for the clinical transformation.