Heidi Klakk

Study protocol. The Childhood Health, Activity, and Motor Performance School Study Denmark (The CHAMPS-study DK)

BackgroundAn increasingly passive life-style in the Western World has led to a rise in life-style related disorders. This is a major concern for all segments of society. The county council of the municipality of Svendborg in Denmark, created six Sport Schools with increased levels of suitable physical activities, which made it possible to study the health outcomes in these children whilst comparing them to children who attended the ‘normal’ schools of the region using the design of a “natural experiment”.MethodsChildren from the age of 6 till the age of 10, who accepted to be included in the monitoring process, were surveyed at baseline with questionnaires, physical examinations and physical and biological testing, including DXA scans. The physical examination and testing was repeated during the early stage of the study. Every week over the whole study period, the children will be followed with an automated mobile phone text message (SMS-Track) asking questions on their leisure time sports activities and the presence of any musculoskeletal problems. Children who report any such problems are monitored individually by health care personnel. Data are collected on demography, health habits and attitudes, physical characteristics, physical activity using accelerometers, motor performance, fitness, bone health, life-style disorders, injuries and musculoskeletal problems. Data collection will continue at least once a year until the children reach grade 9.DiscussionThis project is embedded in a local community, which set up the intervention (The Sport Schools) and thereafter invited researchers to provide documentation and evaluation. Sport schools are well matched with the ‘normal’ schools, making comparisons between these suitable. However, subgroups that would be specifically targeted in lifestyle intervention studies (such as the definitely obese) could be relatively small. Therefore, results specific to minority groups may be diluted. Nonetheless, the many rigorously collected data will make it possible to study, for example, the general effect that different levels of physical activity may have on various health conditions and on proxy measures of life-style conditions. Specifically, it will help answer the question on whether increased physical activity in school has a positive effect on health in children.

Do extra compulsory physical education lessons mean more physically active children - findings from the childhood health, activity, and motor performance school study Denmark (The CHAMPS-study DK)

BackgroundPrimarily, this study aims to examine whether children attending sports schools are more active than their counterpart attending normal schools. Secondary, the study aims to examine if physical activity (PA) levels in specific domains differ across school types. Finally, potential modifications by status of overweight/obesity and poor cardio-respiratory fitness are examined.MethodsParticipants were from the first part of the CHAMPS-study DK, which included approximately 1200 children attending the 0th - 6th grade. At the sports schools, the mandatory physical education (PE) program was increased from 2 to 6 weekly lessons over a 3-year period. Children attending normal schools were offered the standard 2 PE lessons. PA was assessed at two different occasions with the GT3X ActiGraph accelerometer, once during winter in 2009/10 and once during summer/fall in 2010. Leisure time organized sports participation was quantified by SMS track. Based on baseline values in 2008, we generated a high-BMI and a low-cardio-respiratory fitness for age and sex group variable.ResultsThere were no significant differences in PA levels during total time, PE, or recess between children attending sports schools and normal schools, respectively. However, children, especially boys, attending sports schools were more active during school time than children attending normal schools (girls: β=51, p=0.065; boys: β=113, p<0.001). However, in the leisure time during weekdays children who attended sports schools were less active (girls: β=-41, p=0.004; boys: β=-72, p<0.001) and less involved in leisure time organized sports participation (girls: β=-0.4, p=0.016; boys: β=-0.2, p=0.236) than children who attended normal schools. Examination of modification by baseline status of overweight/obesity and low cardio-respiratory fitness indicated that during PE low fit girls in particular were more active at sports schools.ConclusionNo differences were revealed in overall PA levels between children attending sports schools and normal schools. Sports schools children were more active than normal schools children during school time, but less active during leisure time. In girls, less organized sports participation at least partly explained the observed differences in PA levels during leisure time across school types. Baseline status of cardio-respiratory fitness modified school type differences in PA levels during PE in girls.

The intensity of physical activity influences bone mineral accrual in childhood: the childhood health, activity and motor performance school (the CHAMPS) study, Denmark

BackgroundStudies indicate genetic and lifestyle factors can contribute to optimal bone development. In particular, the intensity level of physical activity may have an impact on bone health. This study aims to assess the relationship between physical activity at different intensities and Bone Mineral Content (BMC), Bone Mineral Density (BMD) and Bone Area (BA) accretion.MethodsThis longitudinal study is a part of The CHAMPS study-DK. Whole-body DXA scans were performed at baseline and after two years follows up. BMC, BMD, and BA were measured. The total body less head (TBLH) values were used. Physical activity (PA) was recorded by accelerometers (ActiGraph, model GT3X). Percentages of different PA intensity levels were calculated and log odds of two intensity levels of activity relative to the third level were calculated. Multilevel regression analyses were used to assess the relationship between the categories of physical activity and bone traits.ResultsOf 800 invited children, 742 (93%) accepted to participate. Of these, 682/742 (92%) participated at follow up. Complete datasets were obtained in 602/742 (81%) children. Mean (range) of age was 11.5 years (9.7-13.9). PA at different intensity levels was for boys and girls respectively, sedentary 62% and 64%, low 29% for both genders and moderate to high 9% and 7% of the total time. Mean (range) BMC, BMD, and BA was 1179 g (563–2326), 0.84 g/cm2 (0.64-1.15) and 1393 cm2 (851–2164), respectively. Valid accelerometer data were obtained for a mean of 6.1 days, 13 hours per day.ConclusionsThere 7was a positive relationship between the log odds of moderate to high-level PA versus low level activity and BMC, BMD and BA. Children with an increased proportion of time in moderate to high-level activity as opposed to sedentary and low-level activity achieved positive effects on BMC, BMD and BA.

Effect of four additional physical education lessons on body composition in children aged 8-13 years--a prospective study during two school years.

BackgroundStrategies for combating increasing childhood obesity is called for. School settings have been pointed out as potentially effective settings for prevention. The objective of this paper was to evaluate the effect of four additional Physical Education (PE) lessons/week in primary schools on body composition and weight status in children aged 8–13.MethodsChildren attending 2nd to 4th grade (n = 632) in 10 public schools, 6 intervention and 4 control schools, participated in this longitudinal study during 2 school years. Outcome measures: Primary: Body Mass Index (BMI) and Total Body Fat percentage (TBF%) derived from Dual Energy X ray Absorptiometry (DXA). Secondary: the moderating effect of overweight/obesity (OW/OB) and adiposity based on TBF% cut offs for gender.ResultsIntervention effect on BMI and TBF% (BMI: β -0.14, 95% CI: -0.33; 0.04, TBF%: β -0.08, 95% CI:-0.65;0.49) was shown insignificant. However, we found significant beneficial intervention effect on prevalence of OW/OB based on BMI (OR 0.29, 95% CI: 0.11;0.72). The intervention effect on adiposity based on TBF% cut offs was borderline significant (OR 0.64, 95% CI:0. 39; 1.05).ConclusionFour additional PE lessons/week at school can significantly improve the prevalence of OW/OB in primary schoolchildren. Mean BMI and TBF% improved in intervention schools, but the difference with controls was not significant. The intervention had a larger effect in children who were OW/OB or adipose at baseline.

Overuse and traumatic extremity injuries in schoolchildren surveyed with weekly text messages over 2.5 years

The objectives of this prospective cohort study were to report the incidence, prevalence, and duration of traumatic and overuse injuries during a period of 2.5 years and to estimate the odds of injury types. In all, 1259 schoolchildren, aged 6–12, were surveyed each week with an automated mobile phone text message asking questions on the presence of any musculo‐skeletal problems and participation in leisure‐time sport. Children were examined and injuries classified as overuse or traumatic. The overall injury incidence and prevalence were 1.2% and 4.6% per week, with 2.5 times more overuse than traumatic injuries in lower extremities, and mean injury duration of 5.3 and 4.8 weeks, respectively. A reverse pattern was found for upper extremities, with 3.1 times more traumatic than overuse injuries and mean durations of 3.3 and 5.2 weeks, respectively. Grade level, school type, leisure‐time sport, and seasonal variation were associated with the risk of sustaining lower extremity injuries. Only grade level was associated with upper extremity injuries. The magnitude of overuse and traumatic limb injuries emphasizes the need for health professionals, coaches, and parents to pay special attention in relation to the growing and physically active child.

Six physical education lessons a week can reduce cardiovascular risk in school children aged 6–13 years: A longitudinal study

Aims: Cardiovascular disease (CVD) originates during childhood and adolescence. Schools are potentially effective settings for early public health prevention strategies. The aim of this study was to evaluate the effect of six physical education (PE) lessons on children’s CVD risk. Methods: This longitudinal study in 10 public schools (1218 children, aged 6–13 years), 6 intervention and 4 control schools evaluates a natural experiment, where intervention schools tripled PE to six lessons per week compared to the mandatory two PE lessons in the control schools. Baseline (2008) and 2-year follow-up measures were anthropometrics, cardiorespiratory fitness, blood pressure and blood samples providing lipids and measures for insulin resistance. Based on these variables, a composite risk score was calculated and used for further analysis. Multivariate multilevel mixed effect regression models were used to estimate effect of intervention taking the hierarchical structure of data into account. Individual, class and school were considered random effects. Intra class correlation (ICC) was calculated. Results: Intervention significantly lowered mean of composite risk score with 0.17 SD (95% CI: −0.34 to −0.01). Six PE lessons per week had a beneficial effect on triglycerides (TG) levels (−0.18 SD, 95% CI: −0.36 to 0.00), systolic blood pressure (SBP) (−0.22 SD, 95% CI: −0.42 to −0.02) and insulin resistance (HOMA-IR) (−0.17 SD, 95% CI: −0.34 to 0.01). Conclusions: Six PE lessons at school can reduce children’s CVD risk measured as a composite risk score. The changes in risk score are considered substantial in the perspective of public health strategy for preventing CVD in later life.

Prospective association of adiposity and cardiorespiratory fitness with cardiovascular risk factors in healthy children

This study aimed to examine the prospective association of three different measures of adiposity and cardiorespiratory fitness (CRF) with 2‐year change in cardiovascular disease (CVD) risk factors in children. Two‐year longitudinal data in schoolchildren aged 7–11 years (n = 365–729) was used. Total body fat (TBF) from dual‐energy x‐ray absorptiometry, body mass index (BMI), waist circumference (WC), CRF, blood samples, and blood pressure were obtained in 2008 and 2010 in the Childhood Health, Activity, and Motor Performance School Study in Denmark (CHAMPS study‐DK). Greater adiposity at baseline was associated with increased CVD risk factor levels at follow‐up. The magnitudes of associations were similar regardless of adiposity measure [TBF%: β 0.30, 95% confidence interval (CI): 0.21–0.39; BMI: β 0.24, 95% CI: 0.14–0.33; WC: β 0.20, 95% CI: 0.10–0.31], and no evidence of nonlinear relationships was observed. We found less strong associations of CRF with increase in CVD risk factor levels after adjusting for adiposity; however, increasing CRF was still favorably associated with decrease in CVD risk factor levels among boys. Results suggest that any effort to shift the population distribution of adiposity downward would be valuable for early CVD prevention. The association of CRF with CVD risk factors was largely explained by adiposity, particularly among girls.

Total body fat percentage and body mass index and the association with lower extremity injuries in children: a 2.5-year longitudinal study

Background Overweight youths are generally recognised as being at increased risk of sustaining lower extremity injuries in sports. However, previous studies are inconclusive and choices for measuring overweight are manifold. Objective To examine two different measures of overweight, body mass index (BMI) and total body fat percentage (TBF%), as risk factors for lower limb injuries in a school-based cohort. Study design A longitudinal cohort study. Methods A total of 632 school children, baseline age 7.7–12.0 years, were investigated. Whole body dual energy x-ray absorptiometry scans provided measures of TBF%. Measures of BMI were obtained by standard anthropometric methods. Musculoskeletal complaints were reported by parents answering weekly mobile phone text messages during 2.5 years. Injuries were diagnosed by clinicians. Leisure time sports participation was reported weekly using text messaging. Results During 2.5 years of follow-up, 673 lower extremity injuries were diagnosed. Children being overweight by both BMI and TBF% showed the highest risk of sustaining lower extremity injuries (IRR 1.38 (95% CI 1.05 to 1.81)). Children who were overweight using BMI and TBF% showed the highest risk of sustaining lower extremity injuries (IRR 1.38 (95% CI 1.05 to 1.81)). Conclusions The risk of lower extremity injuries appeared to be increased for overweight children. When comparing two different measures of overweight, overweight by TBF% is a higher risk factor than overweight by BMI. This suggests that a high proportion of adiposity is more predictive of lower extremity injuries, possibly due to a lower proportion of lean muscle mass.

The prospective association of organized sports participation with cardiovascular disease risk in children (the CHAMPS Study-DK)

Objective: To investigate the prospective association of organized leisure‐time sports participation with cardiovascular risk in children. Methods: Students were recruited from 10 public primary schools. From July 2009 to October 2010, parents reported childrens weekly organized leisure‐time sports participation via text messaging. Clustered cardiovascular risk was estimated with a composite score comprising fasting serum triglyceride levels, homeostasis assessment model‐estimated insulin resistance, total to high‐density lipoprotein cholesterol ratio, and systolic blood pressure. Additional outcomes were body mass index categories and fasting serum insulin and glucose concentrations. Associations were explored with generalized estimating equations and reported with beta coefficients (&bgr;) and percent difference per weekly sports session or incidence rate ratios. All models were adjusted for baseline values and other potential confounders. Results: In total, 1197 children (53% female) with a mean age of 8.4±1.4 years were included. Participating in sports for 53 weeks was associated with lower clustered cardiovascular risk (&bgr;, −0.25; 95% CI, −0.41 to −0.10; percent difference, 3.2%; 95% CI, 5.2%‐1.3%). Similar outcomes were observed for log homeostasis assessment model‐estimated insulin resistance (&bgr;, −0.08; 95% CI, −0.12 to −0.04; percent difference, 3.4%; 5.1%‐1.7%) and log insulin (&bgr;, −0.07; 95% CI, −0.11 to −0.04; percent difference, 2.6%; 95% CI, 4.0%‐1.5%). Sports participation was associated with a 20% decreased risk of overweight/obesity (incidence rate ratio, 0.78; 95% CI, 0.64–0.96). Conclusion: Participating in organized leisure‐time sports for approximately 1 year is associated with decreased clustered cardiovascular risk in children. These findings show that participating in youth sports may be an effective strategy to reduce cardiovascular risk in children.

Effects of extra school‐based physical education on overall physical fitness development – the CHAMPS study DK

First, this study aimed to investigate if four extra physical education (PE) lessons per week improved childrens development in physical fitness. Second, to investigate if the extra PE lessons improved development in physical fitness for children with lower levels of fitness at baseline. This study was a longitudinal controlled school‐based study. The study population consisted of 10 Danish public schools with children in preschool to fourth grade (cohorts 0–4) with 2.5‐year follow‐up. Six schools had extra PE and four schools had normal PE. In total 1247 children were included (normal PE = 536, extra PE = 711). Development in fitness was analyzed using a composite z‐score from six fitness tests. Multilevel mixed‐effects linear regression was used to examine the association between school type and development in fitness. Extra PE increased the total development of composite z‐score units among children enrolled in cohort 4 and borderline in cohort 3 with 1.06 (95% confidence interval 0.48–1.65) and 0.52 z‐score units (−0.06 to 1.09), respectively. Children in the lower 50 percentiles increased their development with 0.47 (0.08–0.85) z‐score units. Extra PE in schools improved development in fitness for cohort 4 and borderline for cohort 3 among all children. Extra PE improved fitness development across all cohorts among children with low fitness levels.