title: Contractile behavior of the medial gastrocnemius in children with bilateral spastic cerebral palsy during forward, uphill and backward-downhill gait.
abstract: Plantarflexor tightness due to muscle degenerations has been frequently documented in children with spastic cerebral palsy but the contractile behavior of muscles during ambulation is largely unclear. Especially the adaptability of gastrocnemius muscle contraction on sloped surface could be relevant during therapy.
  
  
  
  Medial gastrocnemius contractions were measured during flat-forward, uphill (+12% incline) and backward-downhill (-12% decline) treadmill gait in 15 children with bilateral cerebral palsy, walking in crouch, and 17 typically developing controls (age: 7-16years) by means of ultrasound and motion analysis. Tracked fascicle and calculated series elastic element length during gait were normalized on seated rest length. Additionally electromyography of the medial gastrocnemius, soleus and tibialis anterior was collected.
  
  
  
  During forward gait spastic gastrocnemii reached 10% shorter relative fascicle length, 5% shorter series elastic element length and showed 37% less concentric fascicle excursion than controls. No difference in eccentric fascicle excursion existed. Uphill gait increased concentric fascicle excursion in children with cerebral palsy and controls (by 23% and 41%) and tibialis anterior activity during swing (by 33% and 48%). Backward downhill gait more than doubled (+112%) eccentric fascicle excursion in cerebral palsy patients.
  
  
  
  Apart from having innately shorter fascicles at rest, flat-forward walking showed that spastic gastrocnemius fascicles work at shorter relative length than those of controls. Uphill gait may be useful to concentrically train push-off skills and foot lift. During backward-downhill gait the gastrocnemius functions as a brake and displays more eccentric excursion which could potentially stimulate sarcomere-genesis in series with repeated training.
authors.affiliation: Orthopaedic Hospital for Children, Behandlungszentrum Aschau GmbH, Bernauer Str. 18, 83229 Aschau im Chiemgau, Germany; Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Philippstraße 13, Haus 11, 10115 Berlin, Germany. Electronic address: m.hoesl@bz-aschau.de.
authors.forename: Matthias
authors.initials: M
authors.lastname: Hösl
authors.affiliation: Orthopaedic Hospital for Children, Behandlungszentrum Aschau GmbH, Bernauer Str. 18, 83229 Aschau im Chiemgau, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Böhm
authors.affiliation: Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Philippstraße 13, Haus 11, 10115 Berlin, Germany.
authors.forename: Adamantios
authors.initials: A
authors.lastname: Arampatzis
authors.affiliation: Department of Biomechanics in Sports, Technische Universität München, Uptown München-Campus D, Georg-Brauchle-Ring 60/62, 80992 München, Germany.
authors.forename: Antonia
authors.initials: A
authors.lastname: Keymer
authors.affiliation: Orthopaedic Hospital for Children, Behandlungszentrum Aschau GmbH, Bernauer Str. 18, 83229 Aschau im Chiemgau, Germany.
authors.forename: Leonhard
authors.initials: L
authors.lastname: Döderlein
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D016022:Case-Control Studies; D002547:Cerebral Palsy / Q000503:physiopathology*; D002648:Child; D004576:Electromyography; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007866:Leg; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology; D016138:Walking / Q000502:physiology*
keywords: Cerebral palsy; Fascicles; Gastrocnemius; Muscle architecture; Sloped walking; Ultrasound