Muscle Injuries in the Older Athlete.

Master athletes (≥40 years) represent a rapidly growing population with muscle injuries that differ substantially from those of younger athletes. Age-related changes, including type II fiber loss, fatty infiltration, fibrosis, tendon degeneration, and prior scarring, can significantly alter biomechanics, injury patterns, imaging appearance, and recovery timelines. This review summarizes epidemiology, key muscle groups, biomechanics, ultrasound and MR imaging features, and structured reporting considerations. Practical recommendations highlight prognostic factors, complications, and imaging strategies tailored to this unique population.