Adaptive dynamics of the leg movement patterns of human infants: III. Age-related differences in limb control

JL Jensen, E Thelen, BD Ulrich… - Journal of Motor …, 1995 - Taylor & Francis
JL Jensen, E Thelen, BD Ulrich, K Schneider, RF Zernicke
Journal of Motor Behavior, 1995Taylor & Francis
In this article, the development of the increasingly differentiated control of the joints
necessary to transform the spontaneous leg movements of early infancy into adaptive and
functional actions is described. The hypothesis—that increasing joint control requires the
capability for disassociation of joint action, the active modulation of joint stiffness, and a
transition from proximal to distal control of the joints—is proposed. Kinematic and kinetic
analyses of the vertical kicks of infants 2 weeks, 3 months, and 7 months of age (as well as a …
Abstract
In this article, the development of the increasingly differentiated control of the joints necessary to transform the spontaneous leg movements of early infancy into adaptive and functional actions is described. The hypothesis—that increasing joint control requires the capability for disassociation of joint action, the active modulation of joint stiffness, and a transition from proximal to distal control of the joints—is proposed. Kinematic and kinetic analyses of the vertical kicks of infants 2 weeks, 3 months, and 7 months of age (as well as a comparative group of adults) indicated increasing joint independence as well as phase-dependent and joint-dependent control modifications. The kicks of the younger infants were dominated by a proximal control strategy and minimal adjustments of the limb energetics during the flexion and extension phases of the kick. By 7 months of age, much larger modulations of the kick phases were observed as well as increasing evidence of distal control. These results revealed kinematic and kinetic patterns of emerging limb control between 2 weeks and 7 months of age.
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