title: Lower extremity skeletal muscle function in persons with incomplete spinal cord injury.
abstract: METHODS
  A cross-sectional study design.
  
  
  OBJECTIVE
  To characterize and specifically quantify impairments in muscle function after chronic incomplete spinal cord injury (SCI).
  
  
  METHODS
  University of Florida, Gainesville, FL, USA.
  
  
  METHODS
  Voluntary and electrically elicited contractile measurements were performed and voluntary activation deficits were quantitatively determined in the knee extensor and ankle plantar flexor muscle groups in 10 individuals with chronic incomplete SCI (C5-T8, ASIA C or D) and age-, gender-, height- and body weight matched healthy controls.
  
  
  RESULTS
  Persons with incomplete-SCI were able to produce only 36 and 24% of the knee extensor torque and 38 and 26% of the plantar flexor torque generated by noninjured controls in the self-reported less-involved and more-involved limbs, respectively (P<0.05). In addition, both indices of explosive or instantaneous muscle strength, torque200 (absolute torque reached at 200 ms) and the average rate of torque development (ARTD) were dramatically reduced in the ankle plantar flexor and knee extensor muscle groups in persons with incomplete-SCI. However, the deficit in instantaneous muscle strength was most pronounced in the ankle plantar flexor muscles, with an 11.7-fold difference between the torque200 measured in the self-reported more involved limb and a 5-fold difference in the less-involved limb compared to control muscles. Voluntary activation deficits ranged between 42 and 66% in both muscle groups. Interestingly, electrically elicited contractile properties did not differ between the groups.
  
  
  CONCLUSIONS
  The resultant impact of incomplete-SCI is that affected muscles not only become weak, but slow to develop voluntary torque. We speculate that the large deficit in torque200 and ARTD in the ankle plantar flexors muscles of persons with incomplete-SCI may limit locomotor function. The results presented in this study provide a quantitative and sensitive assessment of muscle function upon which future research examining rehabilitation programs aimed at restoring muscle function and promoting functional recovery after incomplete-SCI may be based.
authors.affiliation: Department of Physical Therapy, University of Florida, Gainesville, FL 32610, USA.
authors.forename: A
authors.initials: A
authors.lastname: Jayaraman
authors.forename: C M
authors.initials: CM
authors.lastname: Gregory
authors.forename: M
authors.initials: M
authors.lastname: Bowden
authors.forename: J E
authors.initials: JE
authors.lastname: Stevens
authors.forename: P
authors.initials: P
authors.lastname: Shah
authors.forename: A L
authors.initials: AL
authors.lastname: Behrman
authors.forename: K
authors.initials: K
authors.lastname: Vandenborne
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology; D013119:Spinal Cord Injuries / Q000473:pathology / Q000503:physiopathology*; D013997:Time Factors; D019415:Torque