Muscle Power Adaptations in Healthy Males Across the Lifespan During Sit-to-Walk Motion

Healthy aging enhances quality of life by preserving mobility, but declines in muscle power and function make transitions like sit-to-walk (STW) increasingly challenging. While the decline in muscle power with age is well-documented, there is limited understanding of how these power adaptations impact the STW transition across age groups. This study investigates lower limb muscle power adaptations during the STW transition using an EMG-informed neuromusculoskeletal (NMS) model. Results show that muscle power generally declines with age, yet specific adaptations occur. The gluteus maximus and vasti generate the highest relative power across all age groups. The Kruskal- Wallis test reveals significant age-related adaptations, with older males showing increased dorsiflexor power during rising, potentially compensating for declines in other muscles. Post-gait initiation, the vasti group absorbs power, aiding stability and fall prevention. During gait transition, older males exhibit increased power in several key muscles, indicating compensatory mechanisms for stability and mobility. However, reduced dorsiflexor power in the final STW phase suggests a decline in balance. Overall, findings highlight a complex interplay of muscle power changes with aging, revealing both compensatory adaptations and declines, and showing that aging affects muscle groups unevenly.