BACKGROUND: The lockdown measures related to coronavirus disease 2019 (COVID) impacted the health of adolescents by reducing physical activity (PA). The physical changes in response to decreases in PA can be measured with full body composition analysis. The aim of this study was to evaluate the effects of long-term PA restrictions on body fat (BF), fat-free mass (FFM) and skeletal muscle mass (SMM) in adolescents. METHODS: A total of 1669 boys (before PA restriction (G1): 998; after PA restrictions ended (G2): 671; between the ages of 11 and 18 were included. The measured parameters were body mass (BM), visceral fat area (VFA), BF, FFM and SMM. The whole-body composition was evaluated using bioelectrical impedance analysis (BIA). RESULTS: Compared to G1, G2 exhibited an increase in BF between 1.2 and 5.1%. This difference was significant in boys aged 13 to 18 years (p < 0.05). VFA increased between 5.3 and 20.5 cm2; this increase was significant in boys aged 13 to 18 years (p < 0.05). SMM decreased between 2.6 and 3.8%, and this decrease was significant in all age groups (p < 0.05). Changes in body composition were not accompanied by any significant changes in BM. CONCLUSIONS: COVID-19 restrictions reduced PA, resulting in a significant decrease in SMM. This decrease may impact boys' ability to engage in sufficiently varied PA, which may lead to a further decline in PA and subsequent medical consequences in adulthood.

• Keywords
• Body fat, Body mass, Fat-free mass, Physical activity restriction, Skeletal muscle mass, Visceral fat,
• MeSH
• COVID-19 * epidemiology   MeSH
• Child MeSH
• Adult MeSH
• Communicable Disease Control MeSH
• Humans MeSH
• Adolescent MeSH
• Body Composition MeSH
• Adipose Tissue MeSH
• Check Tag
• Child MeSH
• Adult MeSH
• Humans MeSH
• Adolescent MeSH
• Male MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic epidemiology   MeSH

Background and objectives: Body mass index (BMI) is commonly used to assess the proportionality of body mass; however, there are currently no standards for assessing the weight status of the child population for the needs of epidemiological studies. This study aims to establish bioelectric impedance analysis (BIA) standards for assessing the body weight of children (body fat, visceral fat) using BMI percentile growth charts. Materials and Methods: The study was implemented in a group of 1674 children (816 boys and 858 girls), ages 6 to 11. To classify the subjects at a percentile level, the percentile growth charts from the 6th national anthropological study in the Czech Republic were used. Body composition parameters were ascertained by BIA. Results: Body fat (%) and visceral fat standard values were determined for all age categories. The standards were in three-stages, enabling the determination of underweight, normal weight and overweight children aged 6-11 years. For boys with proportionate body mass, standard body fat values ranging from 14.3-16.0% to 15.5-18.0% were determined, while for girls' values ranging from 16.7-19.4% to 18.3-20.5% were determined, depending on age. As far as visceral fat is concerned, standard values in boys ranging from 30.3-36.9 cm2 to 36.1-44.9 cm2 and in girls 30.3-36.9 cm2 to 36.1-44.9 cm2 were determined, depending on age. Conclusions: Standards for assessing weight status are applicable to children aged 6-11 years, while it can be confirmed that BMI can be considered as an objective tool in assessing body mass and body composition in children.

• Keywords
• body fat, body mass index, growth chart, prepubescent children, standards,
• MeSH
• Child MeSH
• Electric Impedance MeSH
• Body Mass Index MeSH
• Humans MeSH
• Schools * MeSH
• Body Weight MeSH
• Adipose Tissue * MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic epidemiology   MeSH

Secular trends of adiposity and motor development in preschool children since the fifties of the last century up to the beginning of this millennium were analyzed so as to reveal possible changes due to continuously differentiating lifestyle. In preschool children (n = 3678) height, weight, skinfold thickness over triceps, subscapular, and suprailiac were measured by Harpenden caliper in 1957, 1977, 1980, 1985, 1990, and 2012. Simultaneously, motor performance was tested by evaluating the achievements in broad jump and throwing a ball, as a marker of adaptation to changing level of physical activity, free games, and exercise. Along the period of five decades the values of skinfold thickness increased significantly until 2012, mainly on the trunk. Simultaneously, the level of motor performance significantly decreased. Modifications of the way of life during the mentioned five decades characterized by sedentarism and inadequate food intake as related to energy output influenced negatively both adiposity and motor performance already in preschool children. Mostly increased deposition of fat on the trunk which is considered as a marker of possible development of metabolic syndrome was apparent already in preschool age, indicating the importance of early intervention concerning also physical activity and availability for exercise since early life.

• MeSH
• Adiposity physiology   MeSH
• Exercise * MeSH
• Child MeSH
• Humans MeSH
• Obesity epidemiology   MeSH
• Child, Preschool MeSH
• Retrospective Studies MeSH
• Body Weight * MeSH
• Life Style MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Male MeSH
• Child, Preschool MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic MeSH