Can foot position really affect shoulder pain in throwing athletes?
*Flat-foot/Over-pronated foot: An over-pronated foot is a hypermobile foot that leads to lack of a rigid lever at push-off, and causes a collapse of the medial arch.
Why does this matter? Every time your foot hits the ground, you are absorbing an equal and opposite ground reaction force. An over-supinated/over-pronated foot leads to sub-optimal joint loading and over-compensation throughout the body.
An over-pronation (pes planus) on the stance foot may alter hip and spinal loading during the wind-up phase of the pitching motion. The increased curvature in your low back (lordosis) causes hyper-abduction and hyper-external rotation of the shoulder joint. This increased torsion throughout the upper extremity could lead to elbow injury, anterior labrum tears, biceps tendinopathy, and GHIRD.
An over-supination (pes cavus) on the lunge foot leads to a more rigid lower extremity that can lead to poor shock absorption and angular deceleration of the throwing motion. Less foot contact area with the ground can also create an unstable surface that hinders the act of deceleration. This can lead to an overuse injury more consistently seen in the bicep and posterior rotator cuff.
Feigenbaum, Luis A. Roach, Kathryn E. Kaplan, Lee D. Lesniak, Bryson. Cunningham, Sean. “The Association of Foot Arch Posture and Prior History of Shoulder or Elbow Surgery in Elite-Level Baseball Pitchers.” Journal of Orthopaedic & Sports Physical Therapy, vol. 43, no. 11, 2013, pp.814-820.