title: Shoulder rotator strength and torque steadiness in athletes with anterior shoulder instability or SLAP lesion.
abstract: OBJECTIVE
  To investigate shoulder rotator strength and steadiness in athletes with anterior instability and superior labrum anterior posterior (SLAP) lesion.
  
  
  METHODS
  Cross-sectional laboratory study.
  
  
  METHODS
  Athletes with anterior shoulder instability (instability group, n=10) and a SLAP lesion (SLAP group, n=10) were compared with healthy athletes matched by age, anthropometrics and sport (control group for shoulder instability, n=10 and control group for SLAP, n=10). Torque steadiness was evaluated with three 10s submaximal isometric contractions (35% of peak torque) with the arm at 90° of shoulder abduction and 90° of external rotation. The mean isometric torque, standard deviation and coefficient of variation were measured from the steadiness trials. To evaluate shoulder rotator strength, concentric isokinetic tests (90°/s, 180°/s) were performed at the 90-90° position and peak torque to body mass and shoulder external to internal rotation ratio variables were analyzed. The variables were tested with the instability and control groups with respect to shoulder instability and between the SLAP and control groups for SLAP lesion using the Mann-Whitney test.
  
  
  RESULTS
  The SLAP group presented a higher coefficient of variation than the SLAP control group (p=0.003). Regarding shoulder strength, the internal and external shoulder rotators were weaker in the instability group than in the instability control group (p<0.05).
  
  
  CONCLUSIONS
  Athletes with anterior shoulder instability presented shoulder rotation weakness, while athletes with a SLAP lesion showed higher torque fluctuation during internal rotation. These results indicate that there are different alterations to strength and sensory motor control in each condition.
authors.affiliation: Department of Physical Therapy, Federal University of São Carlos, São Carlos, Brazil. Electronic address: stela@ufscar.br.
authors.forename: Michele Forgiarini
authors.initials: MF
authors.lastname: Saccol
authors.affiliation: Department of Physical Therapy, Federal University of São Carlos, São Carlos, Brazil.
authors.forename: Gisele Garcia
authors.initials: GG
authors.lastname: Zanca
authors.affiliation: Department of Orthopaedic Surgery and Sports Medicine, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Benno
authors.initials: B
authors.lastname: Ejnisman
authors.affiliation: Center of Studies on Psychobiology and Exercise, Department of Psychobiology, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Marco Túlio
authors.initials: MT
authors.lastname: de Mello
authors.affiliation: Department of Physical Therapy, Federal University of São Carlos, São Carlos, Brazil.
authors.forename: Stela Márcia
authors.initials: SM
authors.lastname: Mattiello
mesh_terms: D000328:Adult; D001265:Athletic Injuries / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D006801:Humans; D007593:Joint Instability; D008023:Ligaments, Articular / Q000293:injuries*; D009119:Muscle Contraction / Q000502:physiology; D017006:Rotator Cuff / Q000503:physiopathology; D019534:Shoulder Impingement Syndrome / Q000503:physiopathology; D012785:Shoulder Joint / Q000503:physiopathology*; D019415:Torque; D055815:Young Adult
keywords: Joint instability; Muscle strength; SLAP lesion; Sensory motor performance; Shoulder joint