Why Shoulder Pulleys Relieve Shoulder Pain
The shoulder is a self-lubricating joint. That means if there is little or no movement, there is no lubrication. “Oil” for the shoulder is stored in a sub-surface tissue sack called the bursa. The only way this “synovial fluid” can be pumped from the bursa through the shoulder is with movement.
Smooth movements in a pain-free range, like those done with a shoulder pulley, cause the shoulder to lubricate itself and prevent it from becoming stiff or frozen.