AbstractBackgroundPeople with hypermobility spectrum disorder (HSD) are in great risk of experiencing shoulder symptoms, but evidence for treatment is sparse. Therefore, the objective was to evaluate the feasibility of 16-week shoulder strengthening programme for improving shoulder strength and function in people with HSD and shoulder symptoms for more than 3 months to inform a future randomised controlled trial (RCT).MethodsTwelve participants (11 females, 39.3 ± 13.9 years) with HSD and shoulder instability and/or pain for more than 3 months underwent a 16-week heavy shoulder strengthening exercise programme three times weekly using exercises targeting scapular and rotator cuff muscles. Primary outcomes were pre-defined research progression criteria including recruitment rate (acceptable, 6 participants/month), assessment duration (acceptable: < 120 min), participant retention (acceptable: > 80% complete intervention), training adherence (acceptable: > 75% adhere to > 36 training sessions) and adverse events (acceptable: minor events with no participants discontinuing the study), besides participant and physiotherapist feedback. Secondary treatment outcomes were assessed using the Western Ontario Shoulder Instability Index (WOSI, 0–2100 better to worse), self-reported pain, kinesiophobia and fatigue, isometric shoulder strength, besides clinical tests for instability, hypermobility, laxity, and proprioception.ResultsRecruitment rate was 5.6/month, assessment duration (mean ± SD) 105 ± 9 min, retention 100%, adherence 83%, and four participants experienced short-lasting soreness or pain. Participant feedback was positive, and physiotherapists found the intervention relevant and applicable to the population. The WOSI total score showed an improvement by 51% (mean ± SD, points: baseline 1037 ± 215; Follow up 509 ± 365; mean change (95% CI), − 528 (− 738, − 318)), and participants reported reduced pain, kinesiophobia and fatigue. Shoulder strength measurements improved by 28–31% (mean change (95% CI), Nm/kg: scaption 0.51 (0.23, 0.78); internal rotation 1.32 (0.70, 1.95) and external rotation 0.89 (0.37, 1.40)), and clinical tests indicated decreased shoulder laxity/instability.ConclusionsThe shoulder strengthening exercise programme was feasible and safe for people with HSD and long-lasting shoulder symptoms. A future RCT, with an improved recruitment strategy, will demonstrate whether the exercise programme is also effective in improving symptoms and muscle-tendon function in this population.Trial registrationClinicalTrials.gov:NCT03547570. Registered on May 3, 2018.