The shoulder rehabilitation challenge faced by athletes participating in sports is characterized by the high risk of overuse injury. Conventional rehabilitation methods for shoulder conditions such as subacromial pain syndrome (SAPS) may not always be effective for athletes who require more targeted and personalized rehabilitation . The DAid smart shirt prototype offers a promising solution to address this issue by providing real-time feedback on movement patterns during physiotherapy, leading to more effective and personalized treatment . This study aimed to investigate the effect of the DAid smart shirt-based feedback on the self-reported DASH (the Disability of Arm, Shoulder, and Hand or DASH) scores during physiotherapy in patients with subacromial pain syndrome who participate in sports, characterized by a high risk for overuse injury. A randomized controlled trial was performed where patients with subacromial pain syndrome had to perform the assigned training exercises while using the DAid smart shirt system. The results showed that the self-reported improvement in DASH scores after the 8-week treatment statistically significantly (p < 0.001) differs between the treatment and control groups. The study concludes that the use of the DAid smart shirt-based feedback for the physiotherapy of subacromial pain syndrome in patients, participating in high-risk for overuse injury sports, provides a better self-reported improvement, as compared to the conventional methods.