Biomechanical adaptation patterns (BAPs) exist in all of us to some degree. However, an athlete that repeats the same movement pattern daily, month after month and in the many cases year after year can develop strong BAPs. These patterns contribute to undesirable asymmetrical activity even when the athlete is not active in their sport. Baseball is an activity that develops and almost requires BAPs. Patterns usually begin early on as one trains or performs in a certain position. The specific kinetic demands that each position places an athlete in, contribute to the neurologic, feed-forward, developmental processes that can result in very desirable or undesirable movement.
The undesirable pattern is usually predictable, measurable, and consistent regardless if it is reciprocal or alternating nature. It is important for these BAPs to exist to some degree so the baseball player can excel at the position they play. But it is also important that symmetry and maximal joint movement are maintained and not sacrificed due to contralateral or antagonistic over use. This is where most structural imbalances begin and nagging injuries result when these BAPs aren’t challenged or balanced through biomechanical, symmetrical activity.
The most likely movement lost in a baseball player, because of strong neuromechanical development of BAPs, is rotation. The most likely joint affected, regardless of the player’s position, is the femoral-acetabular joint or the acetabular-femoral joint depending on how you approach the myokinematic process. Lumbo-pelvic-femoral symmetry and stability is the foundation for proper trunk rotation, scapula- thoracic rotation, humeral-thoracic rotation and humeral-glenoid rotation. This can influence rotation on either the dominant or non-dominant upper extremity. For example, lack of internal rotation of the femoral-acetabular joint on the left can contribute to limited internal rotation of the right humeral-glenoid joint because of the myokinematic process that takes place secondary to poor inhibition of the BAP that has developed.
Lumbo-pelvic-femoral myokinematics can be evaluated through femoral-acetabular rotation and adduction assessment. This can begin a process of developing a corrective or restorative program. The goals are to reduce active and passive asymmetries that predispose the athlete to overuse, underuse, and misuse of dependent interactive joints and muscles above and below the lumbo-pelvic-femoral complex.
Specific contribution of the hamstrings and adductors to internal rotation of the femoral-acetabular and acetabular-femoral joint is an important factor. Their ability or inability to internally rotate during non-weight bearing and weight bearing activity can determine the course, extent, and development of BAPs.
To restore and maintain functional symmetry at the lumbo-pelvic-femoral complex and at the trunk, the baseball player must have sufficient, symmetrical strength at the hamstrings to reposition the hemi-pelvis appropriately. He must also have sufficient, symmetrical strength at the adductors to contribute form closure of the pelvic inlet and internal rotation of the femur. Symmetrical gluteal strength is also required for dynamic single leg stance control. So the next time you address a pitcher’s right shoulder instability you might want to also compare left femoral-acetabular adduction ROM and internal rotation strength to the right.