Ligaments become thicker and stronger when regularly stressed, a biological process called Davis's Law.

Davis's Law is the soft-tissue equivalent of Wolff's Law, which describes how bones adapt to stress. Named after American orthopedic surgeon Henry Gassett Davis, who described the phenomenon in his 1867 book 'Conservative Surgery,' the law explains how ligaments, tendons, and fascia remodel themselves based on the mechanical demands placed upon them. When soft tissue is placed under tension, fibroblasts—the primary cells in connective tissue—increase the production of Type I collagen and proteoglycans.This remodeling process is highly specific to the direction of the load. The newly formed collagen fibers align themselves along the lines of stress to maximize tensile strength and structural integrity. Research published in the Journal of Applied Physiology indicates that regular resistance training can increase the cross-sectional area of ligaments by up to 20% over several months. This adaptation is a protective mechanism that reduces the risk of ruptures and sprains during high-impact activities.Conversely, the law also dictates that tissues will shorten and weaken if they are not regularly stretched or loaded. For instance, prolonged immobilization in a cast can lead to significant ligament atrophy and a loss of flexibility within just six weeks. This occurs because the body reabsorbs collagen fibers that it deems unnecessary for current activity levels. Therefore, physical therapists utilize Davis's Law to rehabilitate injuries by applying gradual, controlled stress to help tissues regain their original strength.