Objectively assessed physical activity and aerobic fitness in a population-based sample of Norwegian 9- and 15-year-olds

Improving the fitness and physical activity levels of primary school children: results of the Fit-4-Fun group randomized controlled trial

OBJECTIVE

To evaluate the impact of a multi-component school-based physical activity intervention (Fit-4-Fun) on health-related fitness and objectively measured physical activity in primary school children.

METHODS

Four Hunter primary schools were recruited in April, 2011 and randomized by school into treatment or control conditions. Participants included 213 children (mean age = 10.72 years ± 0.6; 52.2% female) with the treatment group (n = 118) completing the 8-week Fit-4-Fun Program. Participants were assessed at baseline and 6-month follow-up, with a 91% retention rate. Cardio-respiratory fitness (CRF) (20 m shuttle run) was the primary outcome, and secondary outcomes included body composition (BMI, BMI(Z)), muscular fitness (7-stage sit-up test, push-up test, basketball throw test, Standing Jump), flexibility (sit and reach) and physical activity (7 days pedometry).

RESULTS

After 6-months, significant treatment effects were found for CRF (adjusted mean difference, 1.14 levels, p < 0.001), body composition (BMI mean, -0.96 kg/m(2), p < 0.001 and BMI z-score mean -0.47 z-scores, p < 0.001), flexibility (sit and reach mean, 1.52 cm, p = 0.0013), muscular fitness (sit-ups) (mean 0.62 stages, p = 0.003) and physical activity (mean, 3253 steps/day, p < 0.001). There were no group by time effects for the other muscular fitness measures.

CONCLUSIONS

A primary school-based intervention focusing on fitness education significantly improved health-related fitness and physical activity levels in children.

Correlates of weight status among Norwegian 11-year-olds: The HEIA study

Background

The underlying mechanisms of overweight and obesity in adolescents are still not fully understood. The aim of this study was to investigate modifiable and non-modifiable correlates of weight status among 1103 Norwegian 11-year-old adolescents in the HEalth in Adolescents (HEIA) study, including demographic factors such as gender and parental education, and behavioral factors such as intake of sugar-sweetened beverages, snacks and breakfast consumption, watching TV and playing computer games, physical activity and sedentary time.

Methods

Weight and height were measured objectively, body mass index (BMI) was calculated and International Obesity Task Force cut-offs were used to define weight status. Physical activity and sedentary time were measured by accelerometers. Other behavioral correlates and pubertal status were self-reported by questionnaires. Parental education was reported by the parents on the consent form for their child. Associations were investigated using logistic regressions.

Results

There were gender differences in behavioral correlates of weight status but not for weight status itself. Adolescents with parents in the highest education category had a 46% reduced odds of being overweight compared to adolescents with parents in the lowest education category. Adolescents with parents with medium education had 42% lower odds of being overweight than adolescents with parents with the lowest education category. Level of parental education, breakfast consumption and moderate to vigorous physical activity were positively associated with being normal weight, and time watching TV was positively associated with being overweight for the total sample. Gender differences were detected; boys had a doubled risk of being overweight for every additional hour of watching TV per week, while for girls there was no association.

Conclusions

The present study showed a social gradient in weight status in 11-year-olds. Both breakfast consumption and moderate to vigorous physical activity were inversely associated with weight status. No associations were found between intake of sugar-sweetened beverages and snacks, playing computer games and weight status. Watching TV was positively associated with weight status for boys but not for girls. Interventions are needed to gain more insight into the correlates of change in weight status.

Experiences from a randomised, controlled trial on cycling to school: Does cycling increase cardiorespiratory fitness?

Aims: The objective of the present study was to investigate the effect of a 12-week randomised controlled cycling-to-school trial on cardiorespiratory fitness. Methods: A total of 53 10- to 13-year-old children from one public school were included. The children were randomised into either a cycling group or a control group. The cycling group was encouraged to cycle to and from school each day during a period of 12 weeks. Peak oxygen consumption (VO2peak) and anthropometrical data (weight and height) were measured at baseline and at the end of the 12-week period. Results: No significant differences were observed in VO2peak change over the 12-week period between the cycling group and the control group (49.7 ml O2/min/kg vs. 50.6 ml O2 /min/kg; effect size=−0.13, F=0.495, p=0.486). Within the intervention group, 69.2% (95% CI 50.1–88.2) started cycling, and within the control group 40.8% (95% CI 20.9–60.5) started cycling. Given that several children in both groups (intervention and control) started cycling to school, re-analyses were conducted between those starting cycling and those not starting cycling. At follow up, a significant difference between those starting cycling and those who did not starting cycling was observed in VO2peak (51.7 ml O2/min/kg vs. 47.9 ml O2/min/kg; effect size=0.49, F=8.145, p=0.007), after adjustment for baseline scores, gender and age. Conclusions: This study indicates that cycling to school improves cardiorespiratory fitness.

Bicycling to school improves the cardiometabolic risk factor profile: a randomised controlled trial

OBJECTIVES

To investigate whether bicycling to school improves cardiometabolic risk factor profile and cardiorespiratory fitness among children.

DESIGN

Prospective, blinded, randomised controlled trial.

SETTING

Single centre study in Odense, Denmark

PARTICIPANTS

43 children previously not bicycling to school were randomly allocated to control group (n=20) (ie, no change in lifestyle) or intervention group (ie, bicycling to school) (n=23).

PRIMARY AND SECONDARY OUTCOME MEASURES

Change in cardiometabolic risk factor score and change in cardiorespiratory fitness.

RESULTS

All participants measured at baseline returned at follow-up. Based upon intention-to-treat (ITT) analyses, clustering of cardiometabolic risk factors was lowered by 0.58 SD (95% CI -1.03 to -0.14, p=0.012) in the bicycling group compared to the control group. Cardiorespiratory fitness (l O(2)/min) per se did not increase significantly more in the intervention than in the control group (β=0.0337, 95% CI -0.06 to 0.12, p=0.458).

CONCLUSIONS

Bicycling to school counteracted a clustering of cardiometabolic risk factors and should thus be recognised as potential prevention of type 2 diabetes mellitus and cardiovascular disease (CVD). The intervention did, however, not elicit a larger increase in cardiorespiratory fitness in the intervention group as compared with the control group.

TRIAL REGISTRATION

Registered at http://www.clinicaltrials.gov (NCT01236222).

Accelerometer-measured daily physical activity related to aerobic fitness in children and adolescents

Maximum oxygen uptake (VO(2PEAK)) is generally considered to be the best single marker for aerobic fitness. While a positive relationship between daily physical activity and aerobic fitness has been established in adults, the relationship appears less clear in children and adolescents. The purpose of this paper is to summarise recently published data on the relationship between daily physical activity, as measured by accelerometers, and VO(2PEAK) in children and adolescents. A PubMed search was performed on 29 October 2010 to identify relevant articles. Studies were considered relevant if they included measurement of daily physical activity by accelerometry and related to a VO(2PEAK) either measured directly at a maximal exercise test or estimated from maximal power output. A total of nine studies were identified, with a total number of 6116 children and adolescents investigated. Most studies reported a low-to-moderate relationship (r = 0.10-0.45) between objectively measured daily physical activity and VO(2PEAK). No conclusive evidence exists that physical activity of higher intensities are more closely related to VO(2PEAK), than lower intensities.

Assessment of a two-year school-based physical activity intervention among 7-9-year-old children

Background

Physical activity (PA) in children has declined in recent decades, highlighting the need for effective intervention programs for school-aged children. The main objective of this study was to assess to what extent PA during and after school hours changed among children who received a progressive two-year long intervention vs. that of children who only received general curriculum-based PA.

Methods

A cluster randomized intervention study was conducted and six elementary schools randomly assigned to serve as control- or intervention schools. All children attending second grade (mean age = 7.4 years - born in 1999) were invited to participate in the fall of 2006 (N = 320, 82% participated), again in 2007 (midpoint) and 2008 (end of intervention). The intervention consisted of multi-component PA-intervention during school hours and was conducted by teachers at each intervention school. PA was assessed by means of accelerometers and subjectively at the intervention schools via teachers' PA log-books.

Results

There was no difference in PA intensity (minutes of moderate-to-vigorous physical activity - min of MVPA) between the two study groups at baseline, but children in the intervention schools were more physically active at moderate-to-vigorous intensity compared to those in control schools after one year of intervention (mean difference of MVPA_log-minutes: 0.61, 95%CI: 0.02, 1.20, p = 0.04). Moreover, the model for minutes of MVPA during school hours, showed a significant three-way interaction between time at mid-point, group and gender (mean difference of MVPA_log-minutes: 1.06, 95%CI: 0.15, 1.97, p = .02), indicating a significantly greater increase among the boys in the intervention schools compared to girls. No difference in PA was detected between the study groups at the end of the study period after two years of intervention.

Conclusions

The results suggest that the objective of increasing PA at school was met after one year of intervention, and it was more pronounced among boys. The lack of increase at the end of the study period suggested that any increase in PA during school may highly depend on both motivation and training of general teachers. Boys may respond better to PA interventions such as the one described in this study.

Improving health-related fitness in children: the Fit-4-Fun randomized controlled trial study protocol

BACKGROUND

Declining levels of physical fitness in children are linked to an increased risk of developing poor physical and mental health. Physical activity programs for children that involve regular high intensity physical activity, along with muscle and bone strengthening activities, have been identified by the World Health Organisation as a key strategy to reduce the escalating burden of ill health caused by non-communicable diseases. This paper reports the rationale and methods for a school-based intervention designed to improve physical fitness and physical activity levels of Grades 5 and 6 primary school children.

METHODS/DESIGN

Fit-4-Fun is an 8-week multi-component school-based health-related fitness education intervention and will be evaluated using a group randomized controlled trial. Primary schools from the Hunter Region in NSW, Australia, will be invited to participate in the program in 2011 with a target sample size of 128 primary schools children (age 10-13). The Fit-4-Fun program is theoretically grounded and will be implemented applying the Health Promoting Schools framework. Students will participate in weekly curriculum-based health and physical education lessons, daily break-time physical activities during recess and lunch, and will complete an 8-week (3 × per week) home activity program with their parents and/or family members. A battery of six health-related fitness assessments, four days of pedometery-assessed physical activity and a questionnaire, will be administered at baseline, immediate post-intervention (2-months) and at 6-months (from baseline) to determine intervention effects. Details of the methodological aspects of recruitment, inclusion criteria, randomization, intervention program, assessments, process evaluation and statistical analyses are described.

DISCUSSION

The Fit-4-Fun program is an innovative school-based intervention targeting fitness improvements in primary school children. The program will involve a range of evidence-based behaviour change strategies to promote and support physical activity of adequate intensity, duration and type, needed to improve health-related fitness.

TRIAL REGISTRATION NO

Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12611000976987.

Improving health-related fitness in children: the Fit-4-Fun randomized controlled trial study protocol

BACKGROUND

Declining levels of physical fitness in children are linked to an increased risk of developing poor physical and mental health. Physical activity programs for children that involve regular high intensity physical activity, along with muscle and bone strengthening activities, have been identified by the World Health Organisation as a key strategy to reduce the escalating burden of ill health caused by non-communicable diseases. This paper reports the rationale and methods for a school-based intervention designed to improve physical fitness and physical activity levels of Grades 5 and 6 primary school children.

METHODS/DESIGN

Fit-4-Fun is an 8-week multi-component school-based health-related fitness education intervention and will be evaluated using a group randomized controlled trial. Primary schools from the Hunter Region in NSW, Australia, will be invited to participate in the program in 2011 with a target sample size of 128 primary schools children (age 10-13). The Fit-4-Fun program is theoretically grounded and will be implemented applying the Health Promoting Schools framework. Students will participate in weekly curriculum-based health and physical education lessons, daily break-time physical activities during recess and lunch, and will complete an 8-week (3 × per week) home activity program with their parents and/or family members. A battery of six health-related fitness assessments, four days of pedometery-assessed physical activity and a questionnaire, will be administered at baseline, immediate post-intervention (2-months) and at 6-months (from baseline) to determine intervention effects. Details of the methodological aspects of recruitment, inclusion criteria, randomization, intervention program, assessments, process evaluation and statistical analyses are described.

DISCUSSION

The Fit-4-Fun program is an innovative school-based intervention targeting fitness improvements in primary school children. The program will involve a range of evidence-based behaviour change strategies to promote and support physical activity of adequate intensity, duration and type, needed to improve health-related fitness.

TRIAL REGISTRATION NO

Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12611000976987.

Changes in cardiorespiratory fitness predict changes in body composition from childhood to adolescence: findings from the European Youth Heart Study

BACKGROUND

Several variables, such as waist circumference (WC) and trunk skinfolds (TS), are indicators of body fat. There is interest in evaluating the effect of cardiorespiratory fitness (CRF) measures on changes in these markers from childhood to adolescence.

PURPOSE

To examine CRF as a potential predictor of changes in body fat over an 8-year follow-up period in a pediatric population.

METHODS

A cohort study of 86 children (44 girls, 42 boys) with a mean age of 9.8 ± 0.3 years who participated in the Portuguese arm of the European Youth Heart Study in 2000 completed a follow-up evaluation in 2008 at a mean age of 17.0 ± 0.4 years. Cardiorespiratory fitness, expressed as maximal oxygen consumption (VO2 max) (mL·kg(-1)·min(-1)), was assessed during an incremental multistage bicycle test to exhaustion. Physical activity (PA) was objectively measured by accelerometry at both periods of evaluation. Fat mass (FM) was assessed using anthropometric models, sum of TS, and WC. Changes were expressed as a percentage of the baseline value. Comparison of means and linear regression analysis were used for data analysis.

RESULTS

While CRF significantly increased among boys (P < 0.05) and decreased in girls (P < 0.01), the percentage of body fat decreased over time in boys (P < 0.01) and increased among girls. Alone, CRF explained 39%, 26%, and 25% of the total variance in WC, FM, and TS, respectively (P < 0.01). Adjusting for PA, sex, and maturation changes, CRF remained a significant predictor of WC (β = -0.335; P < 0.01), FM (β = -2.084; P < 0.01), and TS (β = -1.500; P < 0.01).

CONCLUSION

Changes in CRF are a significant predictor of changes in body fat percentage from childhood to adolescence. School-based PA interventions are encouraged to maintain or improve CRF from childhood and throughout adolescence to prevent increased percentages of body fat, particularly in the abdominal region.

Secular trends in aerobic fitness performance in a cohort of Norwegian adolescents

The purpose of the present study was to compare 3000 m running test results between 1969 and 2009 in a cohort of Norwegian high school pupils. Between 1969 and 2009, a total of 4981 (2827 boys) 3000 m running tests were collected from two Norwegian senior high schools. One-way ANOVA with Tukey's post hoc test was used to analyze the differences in the running times between the different decades. The running times have increased by 10% and 6% from the 1980s to the 2000s for boys and girls, respectively. The distribution showed a decline in aerobic fitness performance for all deciles. The largest negative change in difference was found for pupils with the poorest aerobic fitness level in both boys and girls. The cohort of 16- to 18-year-old boys and girls in the decade 2000-2009 had a poorer aerobic fitness performance in the 3000 m running test compared with earlier decades. The decline in running performance was greater for boys than girls, and the gap between the most and the least fit is becoming considerably larger.

Do physical activity and aerobic fitness moderate the association between birth weight and metabolic risk in youth?: the European Youth Heart Study

OBJECTIVE

Lower birth weight has been associated with a greater risk of metabolic diseases. The aim of this study was examine whether physical activity and aerobic fitness may modify associations between birth weigh and metabolic risk.

RESEARCH DESIGN AND METHODS

The European Youth Heart Study is a population-based study of 9 and 15 year olds (n = 1,254). Birth weight was maternally reported. Skin fold measures were used to calculate body fat and fat mass index (FMI = fat mass [kilograms]/height²). Insulin was measured using fasting blood samples. Physical activity was measured using a hip-worn accelerometer (MTI Actigraph) for >600 min/day for ≥3 days and is expressed as "average activity" (counts per minute) and time spent in above moderate intensity activity (>2000 cpm). Aerobic fitness was assessed using a maximal cycle ergometry test (watts per kilogram fat-free mass).

RESULTS

Higher birth weight was associated with higher FMI (β = 0.49 [95% CI 0.21-0.80]; P = 0.001) and greater waist circumference (0.90 [0.32-1.47]; P < 0.001), adjusted for sex, age-group, sexual maturity, height, and socioeconomic status. Lower birth weight was associated with higher fasting insulin only after further adjustment for adolescent waist circumference and height (-0.059 [-0.107 to -0.011]; P = 0.016). There was no evidence for any modification of the associations after adjustment for physical activity or aerobic fitness.

CONCLUSIONS

The present study did not find any evidence that physical activity or aerobic fitness can moderate the associations among higher birth weight and increased fat mass and greater waist circumference or between lower birth weight and insulin resistance in healthy children and adolescents.

Schoolyard physical activity in 14-year-old adolescents assessed by mobile GPS and heart rate monitoring analysed by GIS

Background: Environmental settings seem to influence the activity patterns of children in neighbourhoods and schoolyards, the latter being an important arena to promote physical activity (PA) in school children. New technology has made it possible to describe free-living PA in interaction with the environment. Aims of study: This study focused on how schoolyard environments influenced the activity patterns and intensity levels in 14-year-old children and whether PA levels in adolescents complied with official recommendations. Another objective was to introduce methodology of using a mobile global positioning system (GPS) device with synchronous heart rate (HR) recordings as a proxy for PA level and a geographical information system (GIS) for spatial analyses. Methods: The sample constituted of 81 children (aged 14 years) from two schools. Movement patterns and activity levels were recorded during lunch break applying a GPS Garmin Forerunner 305 with combined HR monitoring and analysed in a GIS by an overlaid grid and kriging interpolation. Results: Spatial data from GPS recordings showed particular movement patterns in the schoolyards. Low activity levels (mean HR < 120 bpm) dominated in both schools with no gender differences. Activities located to a handball goal area showed the highest monitored HR (>160 bpm) with higher intensity in girls than in boys. Conclusions: Movement patterns and PA generated in GIS for visualisation and analysis enabled direct and realistic description of utilising of schoolyard facilities and activity levels. Linking GPS data and PA levels to spatial structures made it possible to visualise the environmental interaction with PA and which environments promoted low or high PA.

Design of a 20-month comprehensive, multicomponent school-based randomised trial to promote healthy weight development among 11-13 year olds: The HEalth In Adolescents study

Background and purpose: The lack of effective school-based interventions for preventing obesity in children has caused a call for longer duration of interventions and better reporting on design and evaluation methodology. The purpose of this paper is to present the development of the intervention, the design of the effectiveness study, and the test-retest reliability of the main outcome measures in the HEalth In Adolescents (HEIA) study. Methods/design: The HEIA intervention programme was developed based on literature reviews, a social ecological framework, and focus groups. The intervention aimed to increase total physical activity (PA) and consumption of fruit and vegetables and to decrease screen time and consumption of sugar-sweetened beverages. The intervention programme consisted of a classroom component, including dietary behaviour lessons, computer tailoring, fruit/vegetable and PA breaks, and posters, and an environmental component including active transport campaigns, equipment, suggestions for easy improvements of schoolyards, inspirational courses for teachers (all with regards to PA), and fact sheets to parents. The effect of the intervention programme is evaluated in a cluster randomised controlled trial design (intervention = 12 schools, control = 25 schools) including process evaluation. Main outcomes include anthropometry, PA, screen time, and consumption of fruit, vegetables, and sugar-sweetened beverages. A 2-week test— retest study was conducted among 114 pupils. Determinants of the behaviours were assessed. Similar data were collected from parents. Children’s PA was measured objectively by accelerometers. Conclusions: The HEIA study represents a theoretically informed randomised trial comprising a comprehensive set of multilevel intervention components with a thorough evaluation using reliable outcome measures. The study will contribute to a better understanding of determinants of healthy weight development among young people and how such determinants can be modified.

Fat-free mass mediates the association between birth weight and aerobic fitness in youth

OBJECTIVE

To investigate whether birth weight acts as a biological determinant of later aerobic fitness, and whether fat-free mass may mediate this association.

METHODS

The European Youth Heart Study (EYHS) is a population-based cohort of two age groups (9 and 15 years) from Denmark, Portugal, Estonia and Norway. Children with parentally reported birth weight >1.5 kg were included (n = 2 749). Data were collected on weight, height, and skinfold measures to estimate fat mass and fat-free mass. Aerobic fitness (peak power, watts) was assessed using a maximal, progressive cycle ergometer test. Physical activity was collected in a subset (n = 1 505) using a hip-worn accelerometer and defined as total activity counts/wear time, all children with >600 minutes/day for ≥3 days of wear were included.

RESULTS

Lower birth weight was associated with lower aerobic fitness, after adjusting for sex, age group, country, sexual maturity and socio-economic status (ß = 5.4; 95% CI: 3.5, 7.3 W per 1 kg increase in birth weight, p < 0.001). When fat-free mass was introduced as a covariate in the model, the association between birth weight and aerobic fitness was almost completely attenuated (p = 0.7). Birth weight was also significantly associated with fat-free mass (ß = 1.4; 95% CI: 1.1, 1.8, p < 0.001) and fat-free mass was significantly associated with aerobic fitness (ß = 3.6; 95% CI: 3.4, 3.7, p < 0.001). Further adjustment for physical activity did not alter the findings.

CONCLUSION

Birth weight may have long-term influences on fat-free mass and differences in fat-free mass mediate the observed association between birth weight and aerobic fitness.

Cardiorespiratory fitness is a marker of cardiovascular health in renal transplanted children

Children with renal transplants (TX) are at increased risk of cardiovascular (CV) disease. Study objectives were to assess the level of cardiorespiratory fitness (CR fitness) and daily physical activity (PA) in renal TX children and adolescents in relation to traditional cardiovascular risk factors. Laboratory testing included assessment of CR fitness by treadmill exercise testing (VO(2peak)), 24-h ambulatory blood-pressure (ABPM) measurement, oral glucose tolerance test (OGTT), anthropometrics and measurement of lipid levels. PA was self-reported by questionnaire. Twenty-two TX patients with a median (range) age 14.5 (9-18) years were tested. Median V0(2peak) was 66% (36-97) of the expected values compared with controls. Nineteen (86%) children reported <60 min of daily moderate to vigorous physical activity (MVPA). Sixteen (73%) were hypertensive and 8 (34%) were overweight or obese. Four children fulfilled the criteria for a metabolic syndrome. Children with at least 2 of the 3 metabolic risk factors (hypertension, overweight, and glucose intolerance, n=7) achieved significantly lower VO(2peak) compared with those with one or none of these factors (median V0(2peak) 45% and 73% of the expected values respectively, p=0.003). Renal TX children and adolescents have severely impaired CR fitness and PA. Reduced CR fitness was associated with the clustering of CV risk factors. Routine counseling for increased PA is strongly recommended.