Physical Growth, Body Scale, and Perceptual-Motor Development

Unweighting infants reveals hidden motor skills

We investigated the role of rate limiting factors in development using walking as a model system. The achievement of bipedal posture and locomotion are among the most significant achievements in an infant's first year, with poor balance and weak muscles long proposed as the rate limiting factors. Compensating for either may reveal upright motor skill that has not yet emerged in the infant's natural repertoire. To probe this question, we unweighted prewalking infants and measured their performance in various standing and walking behaviors while unweighted compared to baseline. Our secondary objective was to determine if the influence of unweighting was related to infants' locomotor experience. Infants stood unsupported for longer durations with 20% or 40% unweighting. Infants took more independent steps and more steps with one hand held with 40% unweighting. No differences in transition to/from standing were observed. Locomotor experience was related to the influence of unweighting during cruising and walking with a push toy. This is the first report of more advanced motor skills-longer periods of unsupported standing and the emergence of independent walking-revealed by unweighting infants. We interpret our observations to suggest that the refinement of motor control needed to support bipedal posture and locomotion precedes the functional emergence of these skills in infants. In other words, the musculoskeletal components required for walking are slower to develop than the neurological factors - and consequently may be the rate limiters. We further suggest that training regimens including unweighting should be explored in infants with motor delays.

Relationship Among Motor Behavior, Motor Development, and Motor Performance in Children Aged 7-8 Years in China

For children aged 7-8 years in China, "immobility" is a key problem hindering their physical and mental development in recent years. It is widely accepted that motor performance development in children is accompanied by physical and mental growth and development. However, few studies have clarified the relationship among motor behavior, motor development and motor performance. To bridge this knowledge gap, an empirical analysis of children aged 7-8 years in China was conducted. This study developed scales for testing motor performance, motor behavior and motor performance, respectively, and collected data of these tests on children aged 7-8 years in China. Canonical correlation analysis was used to analyze the correlations among motor performance, motor behavior and motor performance, and partial least squares regression was used to evaluate the relationship between dependent and independent variables. It was found that, for the children aged 7-8 years in China, there were significant positive correlations among the motor performance, motor behavior, and motor development. The three tests were closely related and could be applied to promote children's sports performance through improved training activities for targeting specific indicators. The study found there was no significant differences in the application of the three tests for children with different age and gender. This finding lays a foundation for further testing in older children and meets the measurement requirements of modern medicine's "bio-psycho-social model of health promotion". Additionally, the theoretical motional quotient model of "The Bio-Behavior-Task" is constructed as a comprehensive motor performance evaluation system, aligning with students' physical and mental development standards.

The Role of Walking Experience in the Emergence of Gait Harmony in Typically Developing Toddlers

The ability to walk without support usually develops in the first year of a typically developing toddler’s life and matures further in the following years. Mature walking is characterized by the correct timing of the different gait phases that make up a full gait cycle formed by stance, swing, and double support phases. The harmony of mature walking is given by a specific self-similar structure of the ratios between the durations of these phases (stride/stance, stance/swing, swing/double support), that in adults all converge to the golden ratio (phi, about 1.618). The aim of this longitudinal, prospective, experimental study was to investigate the evolution of this gait harmonic structure in the transition from supported to independent walking. In total, 27 children were recruited and recorded at various stages of locomotor development, ranging from neonatal stepping up to an independent walking experience of about six months. Differently from walking speed that progressively increased with age, the gait phase ratios started to converge to golden value only after the first independent steps, suggesting a relation to the maturation of the walking experience. The independent walking experience seems to represent a trigger for the evolution of a locomotor harmonic pattern in toddlers learning to walk.

Influence of an increased number of physical education lessons on the motor performance of adolescents-A non-interventional cohort study

Increasing the amount of regular physical education lessons in school is currently discussed in many countries in order to increase physical activity in youth. The purpose of this study was to compare the motor performance of pupils from an observation group participating in a school trial of two additional physical education lessons (5 lessons of each 50 min/week) without a specific intervention program to a control group with a regular amount of three physical education lessons (3 lessons of each 50 min/week) as indicated by the standard Austrian school curriculum. In this cohort study motor performance of 140 adolescents (12.7±0.5 years) was assessed by means of the German Motor Performance Test 6–18 over a period of 1.5 years with measurement time points before (T1), after eight months (T2) and at the end of the observation period (T3). Two- and three-way mixed analysis of variance were used to detect time, group and interaction effects. Although the observation group demonstrated a higher total motor performance score at all time points (P = 0.005), the improvement over time in total motor performance (P < 0.001) was more pronounced in the control group. Girls and boys developed differently over time (time*gender interaction: P = 0.001), whereby group allocation did not affect this interaction (time*gender*group: P = 0.167). Anyway, girls of control group tend to benefit most of additional physical education lessons. Sports club members scored significantly higher in motor performance across the observation period (P = 0.018) irrespective of group allocation. These findings indicate that there could be a ceiling effect in what the pupils could achieve in terms of motor performance as the pupils of the observation group might have reached this point earlier than their counterparts in the control group. Nevertheless, sports club membership seems to reveal some benefits. Whether improving quality and specificity of the single physical lessons might be superior to merely adding additional ones needs to be confirmed in future studies.

Underweight and early childhood caries among young children in rural Cambodia: a pilot study

Objectives

To investigate the association between underweight and early childhood caries (ECC) among children aged one to three years in rural Cambodia.

Materials and methods

A total of 200 Cambodian children aged one to three years at several villages in Kampong Cham province participated in this study. The children whose Z scores were below two and three standard deviations were considered as moderately-underweight and severely-underweight. Children whose mid-upper arm circumstance (MUAC) was below 12.5 cm, were regarded as having malnutrition. ECC was recorded following the WHO guidelines. Associated factors were obtained through interviews with caregivers.

Results

33.5% and 7.0% of the children were identified as being moderately-underweight and severely-underweight, respectively. The prevalence of ECC was 61.5%. ECC was significantly associated with children being moderately-underweight (P < 0.05). The prevalence of ECC was higher prevalence of those who with severely-underweight, although significant differences were not observed (P = 0.054). Logistic regressions showed that those with low birth weight (OR = 2.57; 95% CI = 1.03–6.40) and malnutrition (OR = 4.71; 95% CI = 1.08–20.62) were likely to be moderately-underweight and severely-underweight, whereas those who with ECC had more moderately-underweight, although it was not significant (OR = 2.21; 95% CI = 0.97–5.00). Those with low birth weight (OR = 10.68; 95% CI = 2.95–38.65) and ECC (OR = 6.67; 95% CI = 1.02–43.61) were likely to be severely-underweight.

Conclusion

The findings of this study suggest that low birth weight, malnutrition and ECC were associated factors of underweight in this population.

The influence of object size on second-order planning in an overturned cup task

For children, second-order planning in object manipulation, as demonstrated by the end-state comfort (ESC) effect, is constrained by numerous factors. As a step towards delineating the influence of object size, children (ages 6-10, n = 113) and adults (ages 18-25, n = 17) performed an overturned cup task with 8 cup sizes (4.7-8.4 cm diameter). Contrary to the hypothesis, cup size did not predict the overall proportion of trials with ESC. An increase in age and hand length did result in more ESC. Subsequent analyses with children, which focused on each cup size, revealed an increase in the ratio of hand size to cup size resulted in an increase in ESC with the 4.7, 5.2, 6.2, and 6.7 cm cups, age was a significant predictor with 4.7, 5.2, and 6.2 cm cups, and the interaction was significant for the 6.2 cm cup. No other significant results emerged. Together, findings offer preliminary support for the notion that object size does constrain children's motor planning skills to a certain degree (i.e., with large cups); however, further inquiry is warranted to elucidate the link between object size and hand size in children's performance of tasks requiring second-order planning.

Using virtual reality to assess dynamic self-motion and landmark cues for spatial updating in children and adults

The relative contribution of different sources of information for spatial updating - keeping track of one's position in an environment - has been highly debated. Further, children and adults may differ in their reliance on visual versus body-based information for spatial updating. In two experiments, we tested children (age 10-12 years) and young adult participants on a virtual point-to-origin task that varied the types of self-motion information available for translation: full-dynamic (walking), visual-dynamic (controller induced), and no-dynamic (teleporting). In Experiment 1, participants completed the three conditions in an indoor virtual environment with visual landmark cues. Adults were more accurate in the full- and visual-dynamic conditions (which did not differ from each other) compared to the no-dynamic condition. In contrast, children were most accurate in the visual-dynamic condition and also least accurate in the no-dynamic condition. Adults outperformed children in all conditions. In Experiment 2, we removed the potential for relying on visual landmarks by running the same paradigm in an outdoor virtual environment with no geometrical room cues. As expected, adults' errors increased in all conditions, but performance was still relatively worse in teleporting. Surprisingly, children showed overall similar accuracy and patterns across locomotion conditions to adults. Together, the results support the importance of dynamic translation information (either visual or body-based) for spatial updating across both age groups, but suggest children may be more reliant on visual information than adults.

Mind the Gap: Gap Affordance Judgments of Children, Teens, and Adults in an Immersive Virtual Environment

Affordances are possibilities for action that depend on both an observer's capabilities and the properties of the environment. Immersive Virtual Environments (IVEs) have been used to examine affordances in adults, demonstrating that judgments about action capabilities are made similarly to the real world. However, less is known about affordance judgments in middle-aged children and adolescents in IVEs. Differences in rate of growth, decision criteria, and perceived risk could influence affordance judgments for children. In Experiment 1, children, teens, and adults stood in an IVE at ground level or at a height of 15 m, and were asked to view gaps of different widths. Across all age groups, estimates of gap crossing were underestimated at the higher height compared to the ground, consistent with reports of fear and risk of falling. Children, compared to adults, underestimated their maximum crossable gap compared to their actual crossable gap. To test whether this difference was specific to IVEs or a more generalized age effect, children and adults were tested on gap estimates in the real world in Experiment 2. This real world study showed no difference between children and adults, suggesting a unique contribution of the IVE to children's affordance judgments. We discuss the implications for using IVEs to study children's affordances.