Vitamin D has been shown to benefit a diverse range of health functions including muscle function. The aim of the present study was to identify serum 25(OH)D3 levels in a sample of adolescent dancers and compare them to muscle function and injury incidence. We incorporated a cross-sectional design to study 49 pre-professional male and female dancers (17±4.44 yrs, 52.1±6.72 kg, 1.63±0.07 m) in full-time training in Bazil. Serum 25[OH]D3 was analyzed by Enzyme-linked Immunosorbent Assay; quadriceps and hamstring peak torque and muscle fatigue were measured by isokinetic dynamometer at 60 and 300° s−1. Injury type and location in the previous 6-months were determined by self-report questionnaire. Participants were categorized into 2 groups: normal or insufficient/deficient (>or<30 ng/ml 25[OH]D3). Results indicated the normal serum 25[OH]D3 group had significantly lower fatigue rates than the insufficient/deficient group (p<0.05) but not for the other muscle function parameters. Fifty-seven percent of participants reported at least 1 injury. The most common were sprains (33%) and tendinopathies (19%). Injured dancers had significantly lower peak torque at 60°/s. The link between serum 25[OH]D3 and reduced muscle fatigue resistance has not been shown before, though the underlying mechanisms aren’t apparent and the link between muscular strength and injury has been previously evidenced.

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Introduction: The growth and development of children is a product of the interaction of biological andenvironmental factors. Dance practice can optimize various aspects of motor control, coordination andbalance in childhood and adolescence. Objective: The objective of the present study was to verify how the practice of classical ballet, at a professional level, can influence the plantar pressures and balance of children and adolescents, as well as to verify if subjects’ vision and posture of the upper limbs can interfere in this result. Methods: Cross-sectional study performed with 111 girls aged 10 to 15 years who practice classical ballet (n = 56) and non-dancers (n = 55). Anthropometry (BMI), plantar pressures and postural stability (baropodometry platform) were assessed. Three different conditions: eyes open (EO), eyes closed (EC) and arms outstretched (AO) were observed. Data analysis performed by using group comparison and correlation tests. Results: Those who practiced classical ballet placed less weight onto the left forefoot, presented lower values of maximum pressure and plantar surface area in all the evaluated conditions and moved less in the stabilometry analysis. It also observed that ballet dancers were more influenced by vision and positioning of the upper limbs than the group of non-dancers. Length of time as a dancer influenced the results found. Conclusions: Girls who practice classical ballet have specific characteristics of plantar pressure and develop different postural control strategies when compared to typical girls of similar age, especially in the arms outstretch position.

Introduction: Electronic devices have been used by increasingly younger people, leading researchers to investigate the impact of these technologies on the health of developing children. Objective: To investigate the impact of smartphone use on the postural control of Brazilian children 6 to 9 years old.Methods: This cross-sectional study was conducted with 278 children from public schools in Goiânia (Goiás, Brazil). The children were assessed in an orthostatic posture with the computerized baropodometry system in three conditions: eyes open, eyes closed, and using a free smartphone application. Results: The children were 8.36 years old on average, 82% of them were well-nourished, and had a daily mean screen time of 2 hours. The postural control analyses revealed that the children made greater postural adjustments with their eyes closed than with them open. When using the smartphone application, the postural adjustments were similar to those with eyes closed. In the stabilometry, the postural displacements made by the children behaved similarly to the static assessment only in total feet surface area. Conclusion: Smartphone use and absence of visual stimulus in the orthostatic position caused postural instability in children 6 to 9 years old. These findings can contribute to understanding the impact of technologies on children’s development of balance in daily tasks.

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