Chain Reaction: Addressing the Kinetic Chain in Throwing Shoulder Rehabilitation

A baseball player experiences frequent pain in his throwing arm during overhead activities. A clinician performsan evaluation but much to the players surprise, the clinician spendsthe majority of the exam evaluating the players lower extremity. The clinician informs the player that his pain is likely due to rotator cuff, scapular and core and hip muscle weakness. Should the player be concerned that the clinician is not focusing on the area that specifically hurts him?

The answer is no overhead shoulder function can be impacted by the integrity of other body segments.^1-7 When all of the body segments are physiologically sound (adequate/optimized strength, flexibility, stability, etc.),working sequentially to allow a patterned activity to occur (i.e. throwing), and the actions are efficiently produced, it can be said the kinetic chain is working well.^3,8

For example, to effectively throw a ball overhead, hip and trunk stability isessential when a pitcher stands on one leg during their pitching sequence. The pitchers stability, strength and explosive power of the lower extremity during this stance is a major component of the accuracy and velocity of the baseball. Force is developed in the legs and trunk in a closed chain fashion, energy is funneled through the scapula, and the energy is transferred to the arm and finally to the baseball as it is release. This results in the action of throwing a projectile overhead.⁸The kinetic chain coordinates the sequencing of activation, mobilization, and stabilization of body segments to produce the dynamic activity.⁸

The Body Works (and Fails) as a Unit

Understanding that the body works and fails as a unit can help clinicians achieve more successful rehabilitation outcomes, especially when applying this understanding to the physical examinations and treatment plans for overhead athletes. The key difference of the kinetic chain approach compared to other examination and treatment philosophies is that the site of symptomsis notnecessarily the targeted area of treatment. Instead, as in the case above, the kinetic chain approach would identify and address deficits of scapular, hip and core muscle strength, inflexibility of the shoulder, and poor balance or lack of proprioceptor activation within the ankle and foot. Interventions would still be prescribed for the shoulder, but the other deficient areas within the kinetic chain would also be targeted as to improve the whole system.

Kinetic Chain Rehabilitation Framework

A kinetic chain framework for rehabilitating the upper extremity has been described as a six step process:¹

1. Establish proper postural alignment;

2. Establish proper motion at all involved segments;

3. Facilitation of scapular motion via exaggeration of lower extremity/trunk movement;

4. Exaggeration of scapular retraction in controlling excessive protraction;

5. Use the closed chain exercise early; and,

6. Work in multiple planes

The hallmark of this approach is to perform most exercises and maneuvers while either sitting or standing to activate as much of the kinetic chain as possible.^1,5,9 This integrated approach to rehabilitation uses the larger, centralized muscles of the legs, hips, and trunk to drive or propel the arm throughout specific movements.

Ideally, time should be dedicated towards first developing comprehensive strength, mobility, and stability (optimizing anatomy), followed by integrating the newly developed muscle function with shoulder tasks (well-developed motor patterns). Finally, an individual should be progressed to complex tasks that adequately direct and educate the motor system to perform optimally.³

Creating Strong Links

The rehabilitation process of the shoulder needs to address many variables, including the kinetic chain complex. The shoulder is just one of many interdependent links in the kinetic chain. Working on the deficiencies throughout the entire system should result in abenefit to overhead throwing performance. While it may take a moment for the patient to completely understand and adoptthe philosophy, comprehensive treatment of the kinetic chain will help both the site of symptoms but also the many other structures that are contributing to the symptoms.