External rotation (ER) is the lateral rotation of the throwing shoulder that is defined in biomechanics and kinesiology as a transverse movement plane. It is initiated right after foot strike in power arms.
External Rotating of hips transfer the linear lower half energy into the arm, with External Rotation of shoulder transferring energy down the kinetic chain reaction into the elbow. Elasticity is crucial for ER and its range of motion (ROM) capacities. The more ER, the harder you throw, but ER is NOT a conscious motor pattern.
It is dictated upon how efficient and powerful the kinetic chain reaction is with energy flows and transfers. One of VeloPRO's best training benefits lays within improving External Rotation's elastic energy output.
If External Rotation of shoulder is initiated too early or out of sync with lower half energy flows, the results will be premature rotation of hips and front side. This is due to PRR initializing because lower half energy load is too powerful for the shoulder and elbow to withstand. According to engineering principles (especially electrical and impact), energy must be downgraded into a usable form. If not, the result is breakage or an uncontainment of energy.
EQUAL AND OPPOSITE REACTIONS MUST BE PROPORTIONATE
Too much ER (compared to internal rotation) can cause major stress on the throwing shoulder. This is due to energy overloading the deceleration muscles of the throwing shoulder - which is the scapula and labrum. Pitchers with bigger ROMs in ER consistently suffer from scapula and labral injuries. Likewise, too much internal rotation (IR), compared to ER sees trends in elbow injuries - which is the axis point for accelerative energy.