title: Immediate Effect of Positioning Devices on Infant Leg Movement Characteristics.
abstract: To determine the immediate effects of constraining or encouraging positioning devices on leg movement of infants with typical development (TD) and at-risk for developmental delay (AR).
  
  
  
  Twenty-six infants (13 TD, 13 AR) were placed in the supine position, a jungle gym, or a car seat. Movement sensors on infants' ankles measured acceleration and angular velocity. We calculated the number of leg movements, peak acceleration, and peak rotational rate of each leg movement. A 2 (group) × 3 (condition) analysis of variance with repeated measures on condition tested for a group effect, a condition effect, and a group by condition interaction for leg movement quantity, average peak acceleration, and average peak rotation.
  
  
  
  Leg movement quantity and average peak acceleration were significantly lower for the car seat condition compared with the supine position or the gym.
  
  
  
  Positioning device use has an immediate effect on infant leg movement characteristics. Long-term effects remain unknown.
authors.affiliation: Division of Biokinesiology and Physical Therapy (Mss Jiang, Armendi, and Dr Smith), University of Southern California, Los Angeles.
authors.forename: Crystal
authors.initials: C
authors.lastname: Jiang
authors.forename: Joyce T
authors.initials: JT
authors.lastname: de Armendi
authors.forename: Beth A
authors.initials: BA
authors.lastname: Smith
mesh_terms: D000842:Ankle / Q000502:physiology; D002658:Developmental Disabilities / Q000534:rehabilitation*; D005260:Female; D006801:Humans; D007223:Infant; D007866:Leg / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology*; D026741:Physical Therapy Modalities