Exploring the Rotator Cuff
Improving one’s performance in sports and daily activity is a factor of neuromuscular efficiency and metabolic enhancements. To attain proficiency, reaction force must be effectively transferred through force couples at a velocity consistent with the requisite movement speeds of the activity. The attainment of efficient movement is dependent on the muscle’s force production and reduction capabilities, magnitude of reaction force, and proprioceptive management of the action (including postural equilibrium). This is accomplished, in part, through the use of neutralizing and stabilizing muscles to prevent diminution of reaction force across joints and to accelerate the movement as needed for the action. Much of the recent literature has focused on the trunk musculature to transfer ground reaction force across the spinal segments in closed-chain movements. By now many professionals are more familiar with the muscles of the inner unit (transverse abdominis, diaphragm, muscles of the pelvic floor and the thoraco-lumbar fascia) and the role these muscles play in stabilization and energy transfer. These muscles should be trained to functional levels specific with the highest demands of routine stress. This being said there are additional stabilization and energy management demands once the reaction force has been transferred through the trunk. Since most actions outside of slow bipedal locomotion use the upper body, stabilization at the articulation sites of upper limbs is very important. Most of these actions manifest in the hands, therefore energy must effectively reach this terminal area. Analyses of the joints of the upper limbs identify the shoulder as the weak link in the system. Working backward, the wrist is a gliding joint and the elbow a hinge, both of which are very stable joints. The shoulder, though, is an incomplete ball and socket joint, giving up stability for mobility. The glenohumeral articulation, as it is formally referred to, has a shallow fossa which allows the limb to be fully abducted and flexed and provides for large ranges of motion in multiple planes. In fact, the human body is designed specifically for range compared to speed or high force. This factor limits the application of high force in exchange for lower force over a greater range. This fact lends itself to the importance of stability.