title: Bilateral changes in forearm oxygen consumption at rest and after exercise in patients with unilateral repetitive strain injury: a case-control study.
abstract: METHODS
  Case-control study.
  
  
  OBJECTIVE
  To investigate whether oxygen consumption and blood flow at rest and after exercise are lower in the affected arm of patients with repetitive strain injury (RSI) compared to controls, and lower in the healthy nonaffected forearm within patients with unilateral RSI.
  
  
  BACKGROUND
  RSI is considered an upper extremity overuse injury. Despite the local presentation of complaints, RSI may be represented by systemic adaptations. Insight into the pathophysiology of RSI is important to better understand the development of RSI complaints and to develop effective treatment and prevention strategies.
  
  
  METHODS
  Twenty patients with unilateral RSI and 20 gender-matched control subjects participated in this study. Forearm muscle blood flow and oxygen consumption were measured using near-infrared spectroscopy at baseline and immediately after isometric handgrip exercises at 10%, 20%, and 40% of the individual maximal voluntary contraction.
  
  
  RESULTS
  Unilateral RSI resulted in a lower oxygen consumption and blood flow in the affected forearm at baseline and lower oxygen consumption after incremental handgrip exercises compared to controls (P<.05). In addition, exercise-induced blood flow and oxygen consumption in the nonaffected forearm in patients with RSI were similarly reduced.
  
  
  CONCLUSIONS
  Blood flow and oxygen consumption after exercise are similarly attenuated in the affected and nonaffected arms of patients with unilateral RSI. Our findings suggest that, despite the unilateral character in clinical symptoms, RSI demonstrates systemic adaptations in forearm blood flow and oxygen consumption at rest and after exercise.
authors.affiliation: Department of Physiology, Radboud University Nijmegen Medical Centre, The Netherlands.
authors.forename: Jaap J J
authors.initials: JJ
authors.lastname: Brunnekreef
authors.forename: Dick H J
authors.initials: DH
authors.lastname: Thijssen
authors.forename: Jan
authors.initials: J
authors.lastname: Oosterhof
authors.forename: Maria T E
authors.initials: MT
authors.lastname: Hopman
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D012090:Cumulative Trauma Disorders / Q000503:physiopathology*; D005260:Female; D005542:Forearm / Q000098:blood supply / Q000503:physiopathology*; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared