AUTHOR=Järvamägi Merike , Riso Eva-Maria , Reisberg Kirkke , Jürimäe Jaak 

TITLE=Development of Cardiorespiratory Fitness in Children in the Transition From Kindergarten to Basic School According to Participation in Organized Sports

JOURNAL=Frontiers in Physiology

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2022.881364

DOI=10.3389/fphys.2022.881364

ISSN=1664-042X

ABSTRACT=Purpose: This study examined the longitudinal development of cardiorespiratory fitness (CRF) in children in the transition from kindergarten to basic school according to participation in organized sports and estimated the associations of CRF and body composition indices during the transition from childhood to preadolescence. 
Methods: Children participated in the three-staged longitudinal study (Kindergarten, 6.6 years, n=212; 1st Grade, 7.6 years, n=136; 5th Grade, 11.5 years, n=142) for 5 years and were categorized into three groups according to participation in organized sports in study period (whole period, episodically, never). Cardiorespiratory fitness was assessed using 20 m shuttle run test, while body composition was measured by skinfold thicknesses and physical activity was registered with accelerometer. International gender- and age-specific CRF reference normatives were also used to characterize participants.
Results: Children who participated consistently in organized sports had significantly higher CRF level and lower body fatness (31.3 ± 13.5 laps in 20 m shuttle run; 21.1 ± 6.3% body fat) in 11.5 years as compared to children who had never participated in sports clubs (20.7±12.0 laps in 20 m shuttle run; 26.1 ± 6.8% body fat). Body composition and CRF did not associate in consistently trained children. The proportion of 5th Grade children demonstrating age appropriate healthy CRF was almost threefold higher in group of consistent sports trainings among both in boys and girls than among non-members of sports clubs. 
Conclusion: Consistent attendance in organized sports in childhood and early preadolescence ensures higher CRF and more healthier body composition as compared to children who had no experience of organized sports.