The short-term effect of manipulation of selected cervical spinal segments on the peak torque of the rotator cuff in asymtomatic patients with and without mechanical cervical spine dysfunction
Strengthening of the rotator cuff muscles forms an integral part of any rehabilitation programme for the shoulder. Shoulder rehabilitation programmes which incorporate early motion and emphasize strengthening, have a lower incidence of recurrent subluxations and dislocations. If cervical manipulation were proven to increase the strength of the rotator cuff muscles, then this could be used to develop and implement more effective treatment and rehabilitation protocols for patients with musculoskeletal painful shoulders and rotator cuff pathologies, and therefore provide future patients with more effective health care. Studies have shown consistent reflex responses associated with spinal manipulative treatments. These reflex responses have been hypothesized to cause the clinically beneficial effects of decreasing hypertonicity in muscles, pain reduction and increasing the functional ability of the patient, and although spinal manipulation has been shown to affect muscle strength, it has not been extensively researched and it is unclear whether increased muscle strength is yet another reflex effect of manipulation. As the rotator cuff is innervated by nerves arising from the mid and lower cervical spine, it is theorised that dysfunction of the spinal joints adversely affects nerve endings, causing inhibition of nerve function and affecting the rotator cuff. This is congruent with research which describes how there could be a decrease in muscular activity due to interference with the nerve supply of a muscle by means of a spinal joint fixation. In light of this, one could hypothesize that removal of a cervical joint dysfunction by manipulation, could increase motor unit recruitment and muscular activity of the muscles supplied by that cervical level and therefore possibly strengthen the muscles involved. Therefore the aim of this study was to determine whether cervical manipulation could contribute to the strengthening process of the rotator cuff.