Muscles, Movement and Pain
The term “joint play” refers to the small amount of movement in a synovial joint that is independent of voluntary muscle movement, whereas “joint centration” describes the optimal alignment of joints.
Loss of joint play and/or joint centration is often initially expressed by periodic twinges of pain or discomfort. It may also lead to more joint fatigue and greater pain after use. Eventually it may amount to ongoing nagging discomfort or pain during use. So what should Athletic Trainers and manual therapists do first: stabilize or mobilize? Both have significant positive clinical benefits, so it is most advantageous to do both – during the same treatment session if possible.
To reduce wear and tear on joints, functional movement specialists assess and correct aberrant muscle imbalance patterns, allowing forces to be transferred in the most efficient way possible. Think of joint centration like the wheel on a car. If the center of rotation is aligned with the center of the hub, it will deliver the most efficient performance. But when this neutral position becomes misaligned, the wheel spins incorrectly and may lead to future mechanical problems. We commonly see this in "Upper Crossed" postures where slumped shoulders lead to “decentration” of the glenohumeral joint and subsequent rotator cuff impingement syndromes (Fig 1).
Commonly, joint play dysfunction is the cause of secondary muscle changes. The secondary muscle changes are mainly atrophy and spasm. Muscle spasm is the brain's way of preventing painful joint movements. Of course, this whole process is interlinked with the actions of the nervous system. Whatever the reason for the loss of joint play, when a joint is not free to move, the muscles that move it cannot be free to move, and compensations occur (Fig 2).
Of course, all muscles can act as stabilizers or mobilizers depending on joint position and coordinated motor control. Balance of mobilizers and stabilizers acting at a joint results in optimal joint centration. Loss of centration occurs when phasic (mobilizer) muscles are forced to stabilize. Non-optimal joint centration can lead to whole body stress, and, conversely, stressful activities can cause loss of proper joint centration. This is why we must help down-regulate our clients’ sympathetic nervous systems by keeping them moving correctly through specifically designed joint centration corrective exercises.
Erik Dalton, Ph.D. founded the Freedom From Pain Institute™ and developed Myoskeletal Alignment Techniques® for manual and movement specialists. Dr. Dalton is the author of Advanced Myoskeletal Alignment and Dynamic Body. He offers BOC approved continuing education credits through live workshops and home study courses worldwide. Visit www.erikdalton.com to review courses and read published articles about myoskeletal alignment.