Abstract
This study examined cardiovascular adaptations in 8- to 10-year-old schoolchildren after 10months (a full school year) of 3×40minute per week of small-sided ball games (SSG, including football, basketball, and/or floorball) or circuit strength training (CST). The study involved 291 Danish schoolchildren, 8-10 years old, cluster-randomized to SSG (n=93, 4 schools, 5 classes), CST (n=83, 4 schools, 4 classes), or a control group (CON, n=115, 2 schools, 5 classes). Before and after the 10-month intervention, resting heart rate and blood pressure measurements were performed as well as comprehensive transthoracic echocardiography and peripheral arterial tonometry (PAT). Analysis of baseline-to-10-months changes showed between-group differences (P<0.05) after both training interventions in diastolic blood pressure (delta scores: SSG -2.1±6.0mmHg; CST -3.0±7.1mmHg; CON 0.2±5.3mmHg). Moreover, there were between-group differences in delta scores (P<0.05) in interventricular septum thickness (SSG 0.17±0.87mm; CST 0.30±0.94mm; CON -0.15±0.68mm), left-atrial volume index (SSG 0.32±5.13mL/m2 ; CON 2.60±5.94mL/m2 ), and tricuspid annular plane systolic excursion (SSG -0.4±3.3mm; CON: 0.1±3.6mm). No significant between-group differences were observed for the PAT-derived reactive hyperemia index. In conclusion, 10months of 3×40minutes per week of SSG and CST in 8- to 10-year-old children decreased diastolic blood pressure and elicited discrete cardiac adaptations, suggesting that intense physical exercise in school classes can have effects on cardiovascular health in children.
Highlights
IntroductionReductions in physical activity and cardiorespiratory fitness in children are associated with clustering of traditional cardiovascular risk factors, for example, obesity, increased blood pressure, and hypercholesterolemia that track into adult life and are linked to increased risk of cardiovascular disease.[1,2] Physical activity and participation in sport during childhood offer numerous benefits for physical, psychosocial, and cognitive health.[3,4] Current guidelines recommend that children should engage in at least 60 minutes or more of moderate to vigorous physical activity (MVPA) per day, and children with a higher average time engaged in MVPA have a more favorable cardiovascular risk factor profile regardless of the amount of sedentary time.[5,6] the proportion of children who are physically active is decreasing and data from the United States have showed that only 42% of children and 8% of adolescents engage in the recommendedScand J Med Sci Sports. 2018;28(Suppl. 1):[33–41].wileyonlinelibrary.com/journal/sms|34 amount of MVPA, with data from Denmark indicating that in 11-year-old children, the figures are just 17% for boys and 7% for girls.[7,8]While MVPA is the focus of available guidelines, specific characteristics of optimal physical training for children in various age groups have not been established
No baseline differences (P > 0.05) were observed between the three groups, except that systolic blood pressure was significantly lower in circuit strength training (CST) than in control group (CON) (100.4 ± 11.6 vs 104.5 ± 9.5 mm Hg), and more children spent 2-4 hours sitting in front of a screen in CST than in CON (32 vs 9%) (Table 1)
The primary results of the present study were that a 10- month school-based intervention consisting of either small-s ided ball games or circuit strength training elicited cardiovascular adaptations in 9-to 10-year-old children, including lowered diastolic blood pressure (BP) and discrete cardiac adaptations
Summary
Reductions in physical activity and cardiorespiratory fitness in children are associated with clustering of traditional cardiovascular risk factors, for example, obesity, increased blood pressure, and hypercholesterolemia that track into adult life and are linked to increased risk of cardiovascular disease.[1,2] Physical activity and participation in sport during childhood offer numerous benefits for physical, psychosocial, and cognitive health.[3,4] Current guidelines recommend that children should engage in at least 60 minutes or more of moderate to vigorous physical activity (MVPA) per day, and children with a higher average time engaged in MVPA have a more favorable cardiovascular risk factor profile regardless of the amount of sedentary time.[5,6] the proportion of children who are physically active is decreasing and data from the United States have showed that only 42% of children and 8% of adolescents engage in the recommendedScand J Med Sci Sports. 2018;28(Suppl. 1):[33–41].wileyonlinelibrary.com/journal/sms|34 amount of MVPA, with data from Denmark indicating that in 11-year-old children, the figures are just 17% for boys and 7% for girls.[7,8]While MVPA is the focus of available guidelines, specific characteristics of optimal physical training for children in various age groups have not been established. It is noteworthy that high-intensity interval training based on high-intensity aerobic bursts separated by recovery periods of lower intensity may be more effective than moderate continuous training for achieving improvement in cardiovascular risk factors and cardiac function in obese and non-obese children and adolescents.[9,10,11] Football, which is an intense, fun, social, and universally known team sport, has features of high-intensity interval training, and we have previously found considerable increases in aerobic fitness in 9-to 10-year-o ld schoolchildren after only 6 weeks of 2 × 30 minutes per week of intense football or unihockey training.[12]
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