BACKGROUND AND OBJECTIVE: Insufficient iron levels for optimal fetal and infant development is a concern during pregnancy and infancy. The goal of this study was to assess the effects of iron supplementation in pregnancy and/or infancy on motor development at 9 months. METHODS: The study was a randomized controlled trial (RCT) of infancy iron supplementation linked to an RCT of pregnancy iron supplementation, conducted in Hebei, China. A total of 1482 infants were randomly assigned to receive placebo (n = 730) or supplemental iron (n = 752) from 6 weeks to 9 months. Gross motor development (assessed by using the Peabody Developmental Motor Scale, Second Edition, instrument) was the primary outcome. Neurologic integrity and motor quality were secondary outcomes. RESULTS: Motor outcome was available for 1196 infants, divided into 4 supplementation period groups: (1) placebo in pregnancy/placebo in infancy (n = 288); (2) placebo in pregnancy/iron in infancy (n = 305); (3) iron in pregnancy/placebo in infancy (n = 298); and (4) iron in pregnancy/iron in infancy (n = 305). Using the Peabody Developmental Motor Scale, instrument, iron supplementation in infancy but not pregnancy improved gross motor scores: overall, P < .001; reflexes, P = .03; stationary, P < .001; and locomotion, P < .001. Iron supplementation in infancy improved motor scores by 0.3 SD compared with no supplementation or supplementation during pregnancy alone. Effects of iron supplementation in infancy alone were similar to effects with iron in both pregnancy and infancy. CONCLUSIONS: The RCT design supports the causal inference that iron supplementation in infancy, with or without iron supplementation in pregnancy, improved gross motor test scores at 9 months.

Background/objectives Poorer motor development is reported in infants with iron deficiency (ID). The role of timing, duration and severity is unclear. We assessed relations between ID timing, duration, and severity and gross motor scores, neurological integrity, and motor behavior quality at 9 months. Subjects/methods Iron status was determined at birth and 9 months in otherwise healthy term Chinese infants. The 9-month motor evaluation included the Peabody Developmental Motor Scale (PDMS-2), Infant Neurological International Battery (INFANIB), and motor quality factor. Motor outcomes were analyzed by ID timing (fetal–neonatal, infancy), duration, and severity. For severity, we also considered maternal iron status. Results The data were available for 1194 infants. Iron status was classified as fetal–neonatal and infancy ID (n = 253), fetal–neonatal ID (n = 256), infancy ID (n = 288), and not ID (n = 397). Compared with not ID, infants with fetal–neonatal or infancy ID had lower locomotion scores (effect size ds = 0.19, 0.18) and those with ID in both periods (longer duration) had lower locomotion and overall PDMS-2 gross motor scores (ds = 0.20, 0.18); ID groups did not differ. More severe ID in late pregnancy was associated with lower INFANIB Vestibular function (p = 0.01), and total score (p = 0.03). More severe ID in infancy was associated with lower scores for locomotion (p = 0.03), overall gross motor (p = 0.05). Conclusions Fetal–neonatal and/or infancy ID was associated with lower overall gross motor development and locomotion test scores at 9 months. Associations with ID severity varied by ID timing: more severe ID in late pregnancy, poorer neurological integrity; more severe ID in infancy, poorer gross motor development.

We assessed the effect of an acute intense exercise bout on the adaptation and consolidation of a visuomotor adaptation task in children. We also sought to assess if exercise and learning task presentation order could affect task consolidation. Thirty-three children were randomly assigned to one of three groups: (a) exercise before the learning task, (b) exercise after the learning task, and (c) only learning task. Baseline performance was assessed by practicing the learning task in a 0° rotation condition. Afterward, a 60° rotation-adaptation set was applied followed by three rotated retention sets after 1 hr, 24 hr, and 7 days. For the exercise groups, exercise was presented before or after the motor adaptation. Results showed no group differences during the motor adaptation while exercise seemed to enhance motor consolidation. Greater consolidation enhancement was found in participants who exercised before the learning task. Our data support the importance of exercise to improve motor-memory consolidat...

Performance and control of upright bipedal posture requires a constant and dynamic integration of relative contributions of different sensory inputs (i. e., sensory reweighting) to enable effective adaptations as individuals face environmental changes and perturbations. Children with gymnastic experience showed balance performance closer to that of adults during and after proprioceptive alteration than children without gymnastic experience when their center of pressure (COP) was analyzed. However, a particular COP sway can be achieved through performing and coordinating different postural movements. The aim of this study was to assess how children and adults of different gymnastic experience perform and control postural movements while they have to adjust balance during and after bilateral tendon vibration. All participants were equipped with spherical markers attached to their skin and two vibrators strapped over the Achilles tendons. Bipedal stance was performed in three 45-s trials in two visual conditions (eyes open, EO, and eyes closed, EC) ordered randomly in which vibration lasted 10 s. Posture movements were analyzed by a principal component analysis (PCA) calculated on normalized and weighted markers coordinates. The relative standard deviation of each principal movement component (principal position, PP-rSTD) quantified its contribution to the whole postural movements, i.e., quantified the coordinative structure. The first (principal velocities, PV-rSTD) and second (principal accelerations, PA-rSTD) time-derivatives characterized the rate-dependent sensory information associated with and the neuromuscular control of the postural movements, respectively. Children without gymnastic experience showed a different postural coordinative structure and different sensory-motor control characteristics. They used less ankle movements in the anterior-posterior direction but increased ankle movements in medio-lateral direction, presented larger hip and trunk velocities, and exhibited more hip actions. Gymnastic experience during childhood seemed to benefit the development of proprioceptive reweighting processes in children, leading to a more mature form of coordinating and controlling posture similarly to adults.

Physical exercise has been proposed as a viable means to stimulate motor learning. Exercise characteristics, including intensity and duration, may play a role in modulating the exercise effect on motor learning. While some evidence exists regarding the benefits of intense and relatively long exercise, little is known about the effect of short exercise bouts on motor learning, especially in children. This study aimed to assess the effect of long versus short intense exercise bouts on the adaptation and consolidation of a rotational visuomotor adaptation task. The participants were 71 healthy children from two sites divided into three groups: long exercise bout (LONG), short exercise bout (SHORT), and no exercise (CON). Children performed a rotated (clockwise 60° rotation) motor task on four different occasions: an adaptation set and 1 h, 24 h, and 7 days delayed retention sets. Exercise bouts were performed prior to the adaptation set. Results showed a group effect during motor adaptation [F(2,68) = 3.160; p = 0.049; ${\mathrm{\eta }}_{\text{p}}^2$ = 0.087], but no statistical differences were found between groups. Regarding retention tests, both exercise groups (LONG and SHORT) showed superior retention compared to CON group [F(2,68) = 7.102; p = 0.002; ${\mathrm{\eta }}_{\text{p}}^2$ = 0.175]. No differences were found between exercise groups, indicating similar benefits for the two exercise interventions. Overall, whether the exercise duration was long or short, exercise improved motor memory retention as an estimate of memory consolidation process. The use of short exercise bouts may be suitable to improve children’s motor memory consolidation in environments where time constraints exist.

To study the interplay between motor learning and emotional responses of young infants, we developed a contingent learning paradigm that included two related, difficult, operant tasks. We also coded facial expression to characterise emotional response to learning. In a sample of nine-month-old healthy Chinese infants, 44.7% achieved learning threshold during this challenging arm-conditioning test. Some evidence of learning was observed at the beginning of the second task. The lowest period of negative emotions coincided with the period of maximum movement responses after the initiation of the second task, and movement responses negatively correlated with the frequency of negative emotions. Positive emotions, while generally low throughout the task, increased during peak performance especially for learners. Peak frequency of movement responses was positively correlated with the frequency of positive emotions. Despite the weak evidence of learning this difficult task, our results from the learners would suggest that increasing positive emotions, and perhaps down-regulating negative emotional responses, may be important for improving performance and learning a complex operant task in infancy. Further studies are necessary to determine the role of emotions in learning difficult tasks in infancy.