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Background: The timing and coordination of infant kicking may allow for activities that facilitate learning and cognitive development.

Objective: This study examined spontaneous kicking and associations with changes in kicking during a learning paradigm in typically developing infants.

Methods: Ten healthy full-term infants participated in two experiments at 3 months of age: spontaneous kicking and the mobile paradigm. The inter-limb, intra-limb, and spatiotemporal parameters during spontaneous kicking were collected by 3D motion capture. Learning was measured in the mobile paradigm where an infant's leg was tethered to an overhead mobile. The mobile offered visual and auditory reinforcement when the infant kicked. Changes in kicking rate indicate learning. Friedman tests were used to determine the dominant inter-/intra-limb kicking patterns. Spearman's rank correlation coefficients were used to assess the correlations between spontaneous kicking and performance in the mobile paradigm.

Results: A significant negative correlation (r = -0.72, p = 0.03) was observed between the percentages of unilateral kicking and normalized kicking rate during the extinction phase of the paradigm. There was a trend of positive correlation (r = 0.58, p < 0.10) between dissociated hip-ankle joint coupling and the last three-minute of the acquisition phase of the paradigm.

Conclusion: Exploratory kicking behaviors elicited by visual and auditory feedback may be related to lower extremity movement control. Enhancing movement experience through appropriate external feedback may be critical in treatment programs to support infant development. Future studies to assess how exploratory motor behaviors contribute to development in motor and other domains are warranted.