A tissue's tolerance is not a fixed number stamped on it at birth — it drifts across the decades. The collagen of tendon and ligament slowly accumulates cross-links it cannot easily remove, stiffening and losing quality; the turnover that repairs and remodels it slows; and the capacity to adapt to loading, while never abolished, diminishes. The consequence for practice is direct: the same nominal load is not the same stimulus, and not the same risk, at 25 and at 65.