Previous research demonstrates that augmented feedback effectively enhances motor skills and performance in both healthy individuals and those with neurological conditions. However, while the role of Knowledge of Results (KR)-a specific augmented feedback strategy-in supporting motor learning is well-established, its efficacy in improving rehabilitation outcomes remains unclear. Notably, there is a lack of studies in the current literature investigating the effects of augmented feedback strategies in individuals with rotator cuff-related shoulder pain (RCRSP). Given the complex and multidimensional pain neurophysiology associated with RCRSP, a KR intervention is hypothesized to hold significant potential for restoring motor control, correcting pain-driven maladaptive movement patterns, alleviating pain, and recovering function in this population. Therefore, the primary objective of this study is to investigate the effects of a KR intervention on clinical outcomes, physical performance, and psychosocial parameters in individuals with RCRSP. The study is designed as a two-arm, prospective, parallel-group, randomized controlled trial. Eligible participants meeting the inclusion criteria will be randomly allocated to either the intervention (n = 28; standard rehabilitation program+ KR intervention)or control group (n = 28; standard rehabilitation program) using computer-based randomization software (www.sealedenvelope.com). Both groups will undergo the same routine exercise-based treatment protocol over an 8-week period, consisting of one physiotherapist-supervised session per week and a home exercise program on the remaining days. While the control group will solely receive the standard rehabilitation program, the intervention group will additionally receive the KR intervention, wherein their assessment results will be regularly shared throughout the treatment process. Conversely, these data will only be disclosed to the control group participants at the conclusion of the 8-week intervention.

A comprehensive, multidimensional assessment protocol will be conducted to evaluate the clinical, neuromuscular, sensorimotor, and psychosocial effects of the intervention. To ensure consistency, all measurements will be performed by the same physiotherapist. Pain intensity (VAS), disability (SPADI), active and pain-free range of motion (using a smartphone inclinometer for flexion, abduction, and internal/external rotation), isometric external rotation strength (via a handheld dynamometer), and the Global Rating of Change (GROC) will be recorded at baseline and continuously monitored prior to each supervised session. Additionally, at baseline and after the 8-week intervention, further pre- and post-intervention assessments will be conducted. These include isometric external rotation, internal rotation, and scaption strength using a strap-fixated handheld dynamometer (EasyForce), with strength tests being terminated if pain exceeds 5/10 on the VAS. Sensorimotor function will be evaluated by measuring shoulder proprioception via Active Joint Position Sense (AJPS) at a 45° target angle in a 90°/90° position, alongside posterior shoulder endurance tested in a prone position holding 2% of body weight. Psychosocial and behavioral parameters will also be assessed, including kinesiophobia (Tampa Scale of Kinesiophobia), pain catastrophizing (Pain Catastrophizing Scale), avoidance behaviors (ADAP-TR and ASAP-Shoulder scales), patient satisfaction (Single Assessment Numeric Evaluation - SANE), and self-efficacy (Pain Self-Efficacy Questionnaire - PSEQ).

Both groups will undergo an 8-week multimodal, evidence-based shoulder rehabilitation program consisting of one supervised clinical session per week and a home exercise program performed three times daily. The protocol includes patient education focusing on pathophysiology, pain management, and activity modification to improve posture and restrict heavy overhead activities. It also incorporates cryotherapy as needed, and targeted manual therapy involving soft tissue release for the long head of the biceps, pectoralis minor, posterior capsule, and supraspinatus. Furthermore, a structured, pain-guided (VAS < 4/10) bilateral progressive exercise therapy program will be implemented. This comprises stretching of the upper trapezius, pectoralis minor, and posterior capsule for 3 sets of 30 seconds, alongside a specific regimen of progressive strengthening and neuromuscular control exercises. The exercise protocol specifically includes bilateral scapular retraction, internal and external rotation, the push-up plus, the full can exercise, bilateral external rotation with elevation using a resistance band, the lawnmower with diagonal squat, the robbery with squat, and proprioceptive exercises utilizing a laser pointer (Motion Guidance). Exercises will be performed for 3 sets of 10 repetitions during weeks 1 to 4, and progressed to 3 sets of 12 repetitions during weeks 5 to 8. Resistance is established using 30% of 1-Repetition Maximum (1-RM) for free weights or an OMNI-RES EB score of 3-5 for elastic bands. To optimize muscle activation and minimize compensation, movements will initially be restricted to under 90° of elevation, with the full range of motion restored before any increase in external load.

The Knowledge of Results intervention will be administered exclusively to the intervention group once a week for 8 weeks, immediately prior to each supervised treatment session, whereas the control group will receive no such augmented feedback. The objective of this intervention is to systematically provide participants with objective, quantifiable data regarding their task results, enabling them to recognize their performance and cumulative progress through concrete metrics. Upon the completion of the routine assessments the physiotherapist will verbally and numerically report the patient's results for pain intensity (VAS), disability (SPADI), pain-free range of motion, isometric external rotation strength, and perceived recovery (GROC). To maximize patient focus and emphasize the importance of the information, this feedback will be delivered immediately after each assessment set using a clear, emphasized, and slightly elevated tone of voice to distinguish it from ambient noise. For physical performance metrics (range of motion and strength), participants will perform three repetitions; once the joint is returned to the starting position, the physiotherapist will calculate and disclose the arithmetic mean of the three trials, alongside the absolute change compared to the previous week's measurement. Similarly, for clinical parameters (pain, disability, and GROC), both the current scores and the calculated weekly differences will be explicitly communicated. This standardized approach ensures that participants receive immediate, explicit insight into both their current session performance and their longitudinal weekly improvements. For example, "your pain level this week is 4 out of 10, which is a 10% decrease compared to last week."

Inclusion Criteria:

• Aged between 18 and 35 years;
• Presence of unilateral shoulder pain lasting for at least 3 months;
• Confirmed diagnosis of at least one of the following conditions by a physician, based on clinical evaluation and magnetic resonance imaging (MRI) or ultrasonography (USG) findings: subacromial impingement syndrome, subacromial bursitis, rotator cuff tendinopathy, or partial rotator cuff tear (< 1 cm);
• Presence of a positive painful arc during flexion or abduction, at least one positive impingement test (Neer or Hawkins-Kennedy), and provocation of symptoms during resisted humeral external rotation, abduction, or scapular plane elevation at 90° of elevation;
• A physical activity score of 5 or higher according to the Tegner Activity Level Scale.

Exclusion Criteria:

• Presence of bilateral shoulder pain;
• Presence of a full-thickness or massive rotator cuff tear;
• History of shoulder trauma, fracture, or instability;
• Restriction in passive range of motion;
• Receipt of any injection to the shoulder joint within the previous 6 weeks;
• History of previous shoulder surgery or dislocation;
• Pregnancy;
• Presence of cervical radiculopathy symptoms or peripheral nerve entrapment syndromes;
• A score of 14 or higher on the Beck Depression Inventory-II;
• Diagnosis of hypertension, cardiovascular disease, peripheral vascular disease, history of deep vein thrombosis, neurological disorders, systemic inflammation, diabetes, cancer, or rheumatological diseases;
• Presence of obesity or metabolic syndrome;
• Participation in any rehabilitation program for a shoulder problem within the past year;
• Unwillingness to participate in the study (or failure to provide informed consent).

Individual participant data will not be shared because the informed consent obtained from the participants and the ethics committee approval do not cover the public sharing of raw data.

Participants are blinded to their group allocation and are kept naive to the specific details of the alternative treatment protocol.