An underlying principle of the human body during sports and physical activity is that every movement of a limb segment is influenced by the movement or stability of body segments which are its immediate neighbors. While the activity may have as its main purpose the propulsion of an object, e.g. as in throwing a ball, the effectiveness and velocity of that trajectory is a product of forces and movements generated by body segments as far away as the foot. A deficiency in stabilization or movement of any segment between the hand and the foot will influence the speed and trajectory of the object.
Numerous examples of the linkage concept as it applies to the musculoskeletal system are apparent throughout sports performance. Pathology in any segment of the body will influence the performance of the motion. Anyone who has suffered from back pain is well aware that even movement of the arm may elicit a spasm of pain from the back. This occurs because muscles of the spine help to provide a stable platform from which the arm acts.
Another example of linkage exists when looking at ankle sprains. Ankle sprains are frequently associated with weakness of the hip muscles (primarily abductors and adductors). This was documented by our Institute over 20 years ago (see Nicholas, Strizak, Veras, J. Sports Medicine, 1975). Whether the hip weakness is a cause or effect of the ankle sprain is very difficult to ascertain. However, if one accepts the notion that linkage is important, it is necessary to continually assess movement and strength of body segments removed from the site of injury. Rehabilitation of injuries should include any segments which are weak or lacking motion. These are fundamental principles of our rehabilitation procedures.
Just as the parts of the musculoskeletal system are ultimately linked, so are the many organ systems involved in exercise, and these in turn are affected by the integrity of the musculoskeletal system. When studying sports injury and performance must one constantly be aware of the interrelationships that exist. While science and scientific training are becoming more reductionistic in nature, sports medicine must be focused on quality of life and performance outcome measurements.