title: Changes in muscle activity in typically developing children walking with unilaterally induced equinus.
abstract: BACKGROUND
  Distinguishing changes in lower limb muscle activation during gait caused by abnormal motor control or adaptations to the presence of a fixed equinus remains a challenge. The objective of this study was to determine a threshold degree of equinus at which changes in muscle activity occur and to characterize adaptive patterns of muscle activity in typically developing children walking with unilateral induced equinus.
  
  
  METHODS
  Ten typically developing children were included. A customized orthosis was fitted to the right ankle. Five conditions of dorsiflexion limitation were evaluated: 10° dorsiflexion, 0°, 10°, 20° of plantar flexion and maximum plantar flexion. Muscle activity of the rectus femoris, vastus lateralis, hamstring, tibialis anterior and soleus muscles of both limbs was recorded.
  
  
  RESULTS
  Significant changes in muscle activation and co-activation occurred from 10° of plantar flexion in the orthosis limb and from maximum plantar flexion in the contralateral limb. Soleus activation occurred prematurely in terminal swing and increased with the degree of equinus. Tibialis anterior activation was increased during initial and midswing and was decreased during terminal swing. From the -20° condition, hamstring activation was increased during the loading response. Vastus lateralis and rectus femoris activation was increased during stance phase. Similar changes in tibialis anterior and soleus activation occurred on the contralateral side. Changes in co-activation occurred in the soleus/tibialis anterior muscle pair in both limbs.
  
  
  CONCLUSIONS
  This study provides indications regarding changes in muscle activity during simulation of equinus gait which should be helpful for therapeutic decision making.
authors.affiliation: CHRU de Brest, Hôpital Morvan, Service de Médecine Physique et Réadaptation, Brest, France; Laboratoire de Traitement de l'Information Médicale INSERM U1101, Brest, France; Université de Bretagne Occidentale, Brest, France. Electronic address: laetitia.houx@chu-brest.fr.
authors.forename: Laetitia
authors.initials: L
authors.lastname: Houx
authors.affiliation: CHRU de Brest, Hôpital Morvan, Service de Médecine Physique et Réadaptation, Brest, France; Laboratoire de Traitement de l'Information Médicale INSERM U1101, Brest, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Lempereur
authors.affiliation: CHRU de Brest, Hôpital Morvan, Service de Médecine Physique et Réadaptation, Brest, France; Laboratoire de Traitement de l'Information Médicale INSERM U1101, Brest, France; Université de Bretagne Occidentale, Brest, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Rémy-Néris
authors.affiliation: CHU de Nantes, Pôle de Médecine Physique et Réadaptation, Hôpital Saint Jacques, Nantes, France.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Gross
authors.affiliation: CHRU de Brest, Hôpital Morvan, Service de Médecine Physique et Réadaptation, Brest, France; Laboratoire de Traitement de l'Information Médicale INSERM U1101, Brest, France; Université de Bretagne Occidentale, Brest, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Brochard
mesh_terms: D000843:Ankle Joint / Q000503:physiopathology*; D002547:Cerebral Palsy / Q000150:complications / Q000503:physiopathology; D002648:Child; D004576:Electromyography; D004863:Equinus Deformity / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D005528:Foot / Q000503:physiopathology*; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology*; D016138:Walking / Q000502:physiology
keywords: Children; Electromyography; Fixed equinus; Gait; Toe-walking