Effects of Mechanical Loading on the Structure and Function of the Achilles Tendon: From Homeostatic Adaptation to Pathological Degeneration

The Achilles tendon, the largest and strongest tendon in the human body, exhibits dynamic adaptive changes in its structure and function through mechanobiological regulation. This review synthesizes the dual regulatory effects of mechanical loading on Achilles tendon homeostasis and pathology: Moderate mechanical stimulation activates integrin-mediated signaling pathways (including PI3K/Akt and MAPK/ERK cascades), promoting tenocyte proliferation/differentiation, collagen biosynthesis, and orderly remodeling of extracellular matrix (ECM), thereby enhancing tendon stiffness, elastic modulus, and ultimate tensile strength. Conversely, chronic overload or disuse conditions induce collagen disorganization, aberrant matrix metalloproteinase (MMP) expression, and inflammatory cascades, creating a predisposition to tendinopathy and degenerative disorders. Emerging evidence highlights the critical role of mechanotransduction in injury repair, with early-stage progressive loading regimens demonstrating enhanced healing outcomes through optimized ECM metabolism and biomechanical signal propagation. Clinically, individualized load management strategies, including blood flow restriction training and biomaterial-assisted mechanomodulation, show promise in injury prevention and rehabilitation. Future research integrating multi-omics approaches with intelligent load-monitoring technologies may clarify mechanobiological coupling mechanisms and facilitate precision interventions for Achilles tendon disorders.