Immediate Effect of Positioning Devices on Infant Leg Movement Characteristics.

Purpose: 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).

Methods: 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.

Results: Leg movement quantity and average peak acceleration were significantly lower for the car seat condition compared with the supine position or the gym.

Conclusions: Positioning device use has an immediate effect on infant leg movement characteristics. Long-term effects remain unknown.