What effect does back pain have on the movement pattern of the upper limb and trunk during overhead hitting or throwing?
During throwing the thoracic spine influence the scapulo-thoracic position and glenohumeral motion. A thoracic kyphosis produce both abduction and protraction of the scapula and changes the orientation of the glenoid. This reduces the clearing space for the humeral head and increase anterior translation.
Trunk pre-rotation towards the dominant side adds force that obliques externus may be able to generate increased force due to greater ROM. Counter-Clockwise Thoracic rotation limitation (for right handed pitchers in the late cocking phase) will reduce forward acceleration of the throwing arm (Pappas et al., 1985).
The ribs and the costo-vertebral connections limit motion in the thoracic spine but also create a stable base that can translate the forces from the kinetic chain below to the muscles of the upper extremity for a more effective throw.
Thoracic lumbar fascia which anchors numerous muscles and has a role in providing trunk rotation and maintaining the semi-rigid cylinder shape which is important during pitching. It also helps with maintaining the rigidity of the vertebral column. This fascia functions better with the trunk in flexion. Thus, developing excessive lumbar lordosis will reduce this stabilisation effect.
Furthermore, McGill & Hoodless (1990) indicated that the L4/5 disc is subject to rotational forces of 4800N during pitching. The Thoracic lumbar fascia has a crucial role to play to dissipate the rotational forces on the intervertebral discs and facets during pitching (Young et al., 1996). If reduced lumbar lateral flexion exist: During throwing with the humerus in abduction, the lumbar spine needs to lateral flex away from the pitching arm and the trunk needs to rotate to fully able the shoulder to reach the cocking position.
If reduced L4/5 or L5/S1 ROM is present, this will reduce the ‘pivot point’ of the lumbar region. Due to this lack of lower spinal ROM, higher segments need to compensate, placing the pivot point much higher in the lumbar segments but also less efficient transference of force from the pelvis causing increased loading on the upper extremity.
The Psoas muscle attaches to T12-L5 and have an influence on the spinal biomechanics. A shortened Psoas affects the lumbar disks as well as hip extension range of motion (Bogduk et al., 1992).
Burkhart et al., (2000), described increase upper extremity stress due to reduced knee flexion during the cocking phase of the serve. Due to limited knee flexion, force transference is reduced from the lower limb and trunk to the upper limb. This will increase the load on the elbow and shoulder by 23-27%. It is therefore important to have sufficient bilateral hip and knee flexibility to reduced stress on the upper limb. The spine and pelvis are the force generators during limb acceleration in throwing. Kibler (1991) describes hip inflexibilities in the overhead athlete causing improper femur and foot position.
The Thrower’s Painful Hip
Tennis players with tight and excessive strong hip external rotators causing reduced internal rotation on the contralateral side of the serving arm forces the femur into external rotation while the foot is planted. Pappas et al. (1985), documented that pitchers with painful hips on the dominant throwing side have limited and stiff external hips rotators hip rotation.
Shortened hip flexors will increase the anterior pelvic tilt causing poorly controlled lumbar lordosis and reduce stride length (Young et al., 1996). There is a definite relation between SLAP lesions and reduced hip rotation.
- Bogduk, N., Pearcy, M., & Hadfield, G. (1992). Anatomy and biomechanics of Psoas Major. Clinical Biomechanics, 7, 109-119.
- Burkhart, S.S., Morgan, C.D., & Kibler, W.B., (2000). Throwing injuries in the shoulder: the dead arm revisited. Clinical Sports Medicine, 19, 125-158.
- Burkhart, S.S., Morgan, C.D., & Kibler, W.B., (2003). The disabled throwing shoulder: spectrum of pathology Part 1: Patho-anatomy and biomechanics. Arthroscopy, 19(4), 404-420.
- Kibler WB (1991). The role of the scapula in the overhead throwing motion. Contemp Orthop, 22(5); 525-532.
- McGill, S.M., Hoodless, K. (1990). Measured and modelled static and dynamic axial trunk torsion during twisting in males and females. Journal of Biomedical Engineering 12(5):403-409.
- Pappas A.M., Zawacki R.M., (1985). Rehabilitation of the pitching Shoulder American Journal of Sports Medicine 13(4); 223-235.
- Young, L.J., Herring S.A., Press J.M., Casazza B.A., (1996). The influence of the spine on the shoulder in the throwing athlete. Journal of Back and Musculoskeletal rehabilitation 7; 5-17.
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