Mechanical failure in tissue occurs when:

Mechanical failure in tissue occurs when the elastic limit of the tissue is exceeded. This concept is grounded in the biomechanics of how tissues respond to loads and stress. When tissues, such as ligaments, tendons, or muscles, are subjected to forces, they can stretch and deform within their elastic limits. However, once these limits are surpassed—the point at which the material can no longer return to its original shape or state—permanent deformation occurs, leading to mechanical failure. This may manifest as a tear, rupture, or other forms of injury.

The other scenarios, while relevant to understanding tissue mechanics, do not directly trigger mechanical failure. Under tensile load, tissues often operate within their elastic limits until those limits are violated. Continuous compression can lead to fatigue or weakening over time but does not immediately result in failure. A state of rest typically implies no external loads are being applied, and therefore, mechanical failure cannot occur in such a condition. Hence, exceeding the elastic limit is the critical point at which mechanical failure is initiated.