Athletics create impact load which can be deleterious to the musculoskeletal system. These impact loads are attenuated by either deformation of materials external to the body, deformation of tissues, or tearing of tissue and fracture of bone. Muscles act to lower the bending stress on bone and to attenuate the peak dynamic loads from unprotected impulsive loads that can damage musculoskeletal tissues. Athletes should be advised to avoid impulsive loads for which they are unprepared, and to not participate in athletics when their muscles are fatigued.