title: Biomechanics of submaximal recumbent cycling in adolescents with and without cerebral palsy.
abstract: OBJECTIVE
  The purpose of this study was to compare the biomechanics of recumbent cycling between adolescents with cerebral palsy (CP) classified at Gross Motor Function Classification System (GMFCS) levels III and IV and adolescents with typical development (TD).
  
  
  METHODS
  Twenty subjects, ages (X+/-SD) 15.2+/-1.6 years (10 with TD, 10 with CP), participated.
  
  
  METHODS
  Lower-extremity kinematics and muscle activity were measured at 30 and 60 rpm while subjects pedaled on a recumbent cycle. Energy expenditure and perceived exertion were measured during a 5-minute test, and efficiency was calculated. Noncircular data were analyzed with analyses of variance. Circular data were analyzed using circular t tests.
  
  
  RESULTS
  Differences were found between groups for joint kinematics for all motions. Subjects with CP displayed earlier onsets and later offsets of muscle activity, increased co-contraction of agonist and antagonist muscles, and decreased efficiency compared with subjects with TD. There were no differences in perceived exertion.
  
  
  CONCLUSIONS
  Differences in cycling biomechanics between children with CP and children with TD may be due to decreased strength and motor control in the children with CP.
authors.affiliation: Shriners Hospitals for Children, 3551 N Broad St, Philadelphia, PA 19140, USA. tjohnston@shrinenet.org
authors.forename: Therese E
authors.initials: TE
authors.lastname: Johnston
authors.forename: Ann E
authors.initials: AE
authors.lastname: Barr
authors.forename: Samuel Ck
authors.initials: SC
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D001642:Bicycling / Q000502:physiology*; D001696:Biomechanical Phenomena; D002547:Cerebral Palsy / Q000503:physiopathology*; D004576:Electromyography; D004734:Energy Metabolism / Q000502:physiology; D005080:Exercise Test; D006801:Humans; D007596:Joints / Q000502:physiology; D035002:Lower Extremity / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology