Ultrasound evaluation of the subacromial space in healthy subjects performing three different positions of shoulder abduction in both loaded and unloaded conditions

摘要: Abstract Background Subacromial space (SS) narrowing may result in unsafe contact of rotator cuff tendons and bursa with the acromion, possibly promoting pathologies pain. We measured SS asymptomatic subjects after three movements employed for shoulder muscles' training. Participants main outcome measures Twenty-five males (age 24±5years; stature 175±8 cm; body mass 74±12 kg) underwent ultrasound evaluation while executing (WL) without (NL) 4-kg load: 90° abduction (SA) humerus rotation (90° neutral ); SA maximal humeral external er maximum (above 90°) during upright row (UR). For inter-operator reliability analysis, a subset 12 was assessed by two operators. Results Intra/inter-operator coefficients were high (ICC>0.87; standard error measurement range: 0.23–0.51 mm; minimum detectable change 0.61–1.79 mm). ANOVA revealed significant differences between loads (p = 0.003, η 2  = 0.37) angles (p   = 0.72), interaction (p = 0.004,  = 0.45). Normalized values WL higher at vs. UR both (p = 0.002) (p = 0.009). Conclusions When holding load, is larger than positions. In unloaded condition, reduced compared to UR.