title: Upper limb strength in individuals with spinal cord injury who use manual wheelchairs.
abstract: BACKGROUND
  Manual wheelchair users have been found to be at risk for secondary upper extremity injuries.
  
  
  OBJECTIVE
  The primary goal of this study was to compare shoulder strength and muscle imbalance of individuals with paraplegia to case-wise matched unimpaired controls (UC). A secondary goal was to evaluate the impact of age and neurologic level of injury (NLI) on weight-normalized strength (WNS).
  
  
  METHODS
  The SCI group (n = 28) and the UC group (n = 28) completed bilateral shoulder isokinetic strength testing in the sagittal, frontal, and horizontal plane at 60 degrees/second using the BioDex system. Strength ratios, an indicator of muscle imbalance, were also calculated.
  
  
  RESULTS
  No significant difference was seen in shoulder strength or strength ratios between the SCI group and the UC group. However, NLI was significantly related to WNS on several planes in the SCI group. Therefore, we dichotomized the SCI group into equal groups based on an NLI. The Low-SCI group was significantly stronger than the High-SCI group in most planes (P < 0.05). The High-SCI group was significantly weaker than the UC in extension (P < 0.01) and a trend (P < 0.01) was seen in flexion, abduction, and external rotation. The Low-SCI group was significantly stronger in abduction than the UC.
  
  
  CONCLUSIONS
  WNS at the shoulder correlated with NLI. It is likely that this is related to contributions of the trunk and abdominal muscles during testing, since proximal trunk strength aids in generating forces distally. This study and others of strength in individuals with paraplegia may overestimate shoulder strength.
authors.affiliation: Department of Rehabilitation Science and Technology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Aaron L
authors.initials: AL
authors.lastname: Souza
authors.forename: Michael L
authors.initials: ML
authors.lastname: Boninger
authors.forename: Shirley G
authors.initials: SG
authors.lastname: Fitzgerald
authors.forename: Sean D
authors.initials: SD
authors.lastname: Shimada
authors.forename: Rory A
authors.initials: RA
authors.lastname: Cooper
authors.forename: Fabrisia
authors.initials: F
authors.lastname: Ambrosio
mesh_terms: D000328:Adult; D000367:Age Factors; D001132:Arm / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010264:Paraplegia / Q000209:etiology / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology; D012785:Shoulder Joint / Q000502:physiology; D013119:Spinal Cord Injuries / Q000150:complications / Q000503:physiopathology*; D019415:Torque; D014910:Wheelchairs