 The aim of this study is to evaluate the efficacy of coactivation strengthening exercises in patient with RCT compared to regular strengthening exercises. Forty-two participants diagnosed with RCT by an orthopaedic surgeon following a standardized protocol will be randomised to either coactivation or regular strengthening exercises. Participants will perform a 6-week exercise protocols. Outcomes will be measured at baseline, and at three, six, 12, 18 and 24 weeks. The primary outcome is function assessed with the Disabilities of arm, shoulder and Hand DASH questionnaire. Secondary outcomes focus on pain visual analog scale, quality of life Western Ontario Rotator Cuff Index, impression of change Patient Global Impression of Change, subacromial distance ultrasonography and muscular strength manual dynamometer. Investigators expect that coactivation strengthening exercises will be more efficient over the short and long term. 