Importance of Return to Usual and School Activities After Social Isolation in Recovering Vitamin D Concentrations, Physical Fitness, and Motor Performance in Adolescents.

This study aimed to observe adolescents' changes and individual responses regarding the anthropometry, cardiometabolic profile, vitamin D concentrations, physical fitness, and motor competence upon immediate return and three months of school activities after lockdown.
Methods: The study included 28 adolescents (14.8 ± 0.8 years) of both sexes. Anthropometric measures, body composition, cardiometabolic parameters, physical fitness, and motor competence were assessed. A paired t -test was used to compare the frequencies of respondents and the effect size of the results, considering significant p < 0.05.
Results: After three months of school activities, adolescents changed their body composition, reducing % fat mass ( p = 0.008) and increasing fat-free mass ( p = 0.008). In terms of physical fitness, there was increased abdominal resistance ( p < 0.001; ES = -0.42) and motor performance, with reduction in supine-to-stand test time ( p < 0.001; ES = 0.53). There were very beneficial effects in reducing resting heart rate ( p ≤ 0.001; ES = 0.61) and increasing vitamin D concentrations ( p < 0.001; ES = -0.61). After three months of a school routine, the proportions of change in respondents were similar between girls and boys and eutrophic individuals and overweight individuals.
Conclusions: Returning to school activities after lockdown was important for the recovery of vitamin D concentrations, physical fitness, and motor competence, whose responses were independent of the level of adiposity and sex of the adolescents.