Multiscale biomechanical and neuromuscular mechanisms underlying Achilles tendon injury

Achilles tendon injury is a common musculoskeletal disorder that arises from complex interactions among tissue structure, mechanical loading, neuromuscular control, and functional behavior across multiple biological scales. Therefore, a comprehensive understanding of Achilles tendon pathology requires more than a single research approach. It requires an integrative multiscale perspective that links structural, mechanical, biological, and neuromuscular mechanisms. To elucidate the mechanisms underlying Achilles tendon injury, this review systematically examined evidence from diverse research domains, including finite element modeling, animal experiments, and human movement analysis. From a computational modeling standpoint, this review synthesizes how tendon geometry, material properties, and subtendon organization shape stress-strain distributions and contribute to injury susceptibility. Experimental evidence, primarily derived from animal models, is then examined to elucidate mechanisms of load-induced degeneration and tissue repair. Finally, human-based studies are considered to evaluate how kinematic features and neuromuscular adaptations modulate the biomechanical behavior of the Achilles tendon. This review emphasizes that the integration of multiscale and multi-method approaches is essential for advancing the understanding of injury mechanisms, optimizing rehabilitation strategies, and promoting more effective interventions, thereby providing a theoretical foundation for future basic and clinical research.