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

Longitudinal changes in device-measured physical activity from childhood to young adulthood: the PANCS follow-up study

BACKGROUND

There is a lack of longitudinal studies examining changes in device-measured physical activity and sedentary time from childhood to young adulthood. We aimed to assess changes in device-measured physical activity and sedentary time from childhood, through adolescence, into young adulthood in a Norwegian sample of ostensibly healthy men and women.

METHODS

A longitudinal cohort of 731 Norwegian boys and girls (49% girls) participated at age 9 years (2005-2006) and 15 years (2011-2012), and 258 of these participated again at age 24 years (2019-2021; including the COVID-19 pandemic period). Physical activity and sedentary time were measured using ActiGraph accelerometers. Linear mixed models were used to analyse changes in physical activity and sedentary time and whether low levels of childhood physical activity track, i.e., persist into young adulthood (nchange=721; ntracking=640).

RESULTS

The most prominent change occurred between the ages of 9 to 15 years, with an increase in sedentary time (150 min/day) and less time spent in light (125 min/day), moderate (16 min/day), and vigorous physical activity (8 min/day). Only smaller changes were observed between the ages of 15 and 24 years. Changes in moderate-to-vigorous physical activity from childhood to young adulthood differed between subgroups of sex, tertiles of body mass index at baseline and tertiles of peak oxygen uptake at baseline. While the tracking models indicated low absolute stability of physical activity from childhood to young adulthood, children in the lowest quartiles of moderate-to-vigorous (OR:1.88; 95%CI: 1.23, 2.86) and total physical activity (OR: 1.87; 95%CI: 1.21, 2.87) at age 9 years were almost 90% more likely to be in these quartiles at age 24 years compared to those belonging to the upper three quartiles at baseline.

CONCLUSIONS

We found a substantial reduction in physical activity and increase in time spent sedentary between age 9 and 15 years. Contrary to previous studies, using mainly self-reported physical activity, little change was observed between adolescence and young adulthood. The least active children were more likely to remain the least active adults and could be targeted for early intervention.

A Meta-Analysis of Sampled Maximal Aerobic Capacity Data for Boys Aged 11 Years Old or Less Obtained by Cycle Ergometry

The aim of this study was to develop distributions of VO_2max based on measured values that exist in the literature in prepubertal boys using cycle ergometry. PRISMA guidelines were followed in conducting this research. One database was searched for peak and maximal VO₂ values in healthy boys with mean age under 11 years old. Data were split into articles reporting absolute and relative VO_2max values and analyzed accordingly. Multilevel models grounded in Bayesian principles were used. We investigated associations between VO_2max and body mass, year of the study, and country of origin. Differences in "peak" and "maximal" VO₂ were assessed. Absolute VO_2max (Lmin^-1) increases with age (P ~100%) but mean relative VO_2max does not change (P ~100%). Absolute VO_2max is higher in more recent studies (P = 95.7 ± 0.3%) and mean relative VO_2max is lower (P = 99.6 ± 0.1%). Relative VO_2max in the USA is lower compared with boys from other countries (P = 98.8 ± 0.2%), but there are no differences in absolute values. Mean aerobic capacity estimates presented as "peak" values are higher than "maximal" values on an absolute basis (P = 97.5 ± 0.3%) but not on a relative basis (P = 99.6 ± 0.1%). Heavier boys have lower cardiorespiratory fitness (P ≈ 100%), and body mass seems to be increasing faster with age in the USA compared with other countries (P = 92.3 ± 0.3%). New reference values for cardiorespiratory fitness are presented for prepubertal boys obtained with cycle ergometry. This is new, as no reference values have been determined so far based on actual measured values in prepubertal boys. Aerobic capacity normalized to body weight does not change with age. Cardiorespiratory fitness in prepubertal boys is declining, which is associated with increasing body mass over the last few decades. Lastly, this study did not find any statistically significant difference in the sample's mean aerobic capacity estimates using the "peak" and "maximum" distinctions identified in the literature.

Normative values of cardiorespiratory fitness in Croatian children and adolescents

Although defining normative values of cardiorespiratory fitness have been the topic of many Western societies, little evidence has been provided for less developed countries like Croatia. Since cardiorespiratory fitness rapidly declines in Croatian children and adolescents, the newly established normative values would help health-related professionals and physical education teachers to detect 'talented' groups and direct them towards sport and 'risky' groups for planning special interventions. Therefore, the main purpose of the study was to determine normative reference values of cardiorespiratory fitness. A total of 1,612 children and adolescents aged 7-14 years (mean±SD; age 9.7±2.4 years; stature 151.0±17.6 cm; body mass 45.1±19.1 kg; 52.5% girls) participated in this cross-sectional study. Cardiorespiratory fitness was assessed by the Maximal multistage 20-m shuttle run test and the performance was expressed as the number of stages. Maximal oxygen uptake (VO2max) was estimated by equations. Smoothed percentile curves were calculated. Boys outperformed girls in the maximal number of levels achieved after the 20-m shuttle run test and in the VO2max values at each age category. In boys, a gradually higher level of performance between ages 11 and 14 was observed, while in girls the values started to rise after the age of 8. Our study provides one of the first sex- and age-specific normative values for cardiorespiratory fitness assessed by the 20-m shuttle run test in Croatian children and adolescents.

Seasonal Shifts in Children's Sedentary Behaviors, Physical Activity, and Sleep: A Systematic Review and meta-Analysis

Children's movement behaviors (ie, sedentary behaviors, physical activity, and sleep) are related to obesity risk and may vary throughout the year. The purpose of this systematic review is to summarize existing literature on the seasonal variation in physical activity and sleep in children. This study found that children's behaviors fluctuate seasonally and thus, interventions must target behaviors during the times when children's behaviors are the least healthy, specifically during the summer (when children are not in school) and winter. Finally, the paucity of data on seasonal variation in sleep indicates a need for further research in this area.

The Physical Activity and fitness in Childhood Cancer Survivors (PACCS) Study: Protocol for an international, mixed-methods study (Preprint)

Background

Survivors of childhood cancer represent a growing population with a long life expectancy but high risks of treatment-induced morbidity and premature mortality. Regular physical activity (PA) may improve their long-term health; however, high-quality empirical knowledge is sparse.

Objective

The Physical Activity and Fitness in Childhood Cancer Survivors (PACCS) study comprises 4 work packages (WPs) aiming for the objective determination of PA and self-reported health behavior, fatigue, and quality of life (WP 1); physical fitness determination (WP 2); the evaluation of barriers to and facilitators of PA (WP 1 and 3); and the feasibility testing of an intervention to increase PA and physical fitness (WP 4).

Methods

The PACCS study will use a mixed methods design, combining patient-reported outcome measures and objective clinical and physiological assessments with qualitative data gathering methods. A total of 500 survivors of childhood cancer aged 9 to 18 years with ≥1 year after treatment completion will be recruited in follow-up care clinics in Norway, Denmark, Finland, Germany, and Switzerland. All participants will participate in WP 1, of which approximately 150, 40, and 30 will be recruited to WP 2, WP3, and WP 4, respectively. The reference material for WP 1 is available from existing studies, whereas WP 2 will recruit healthy controls. PA levels will be measured using ActiGraph accelerometers and self-reports. Validated questionnaires will be used to assess health behaviors, fatigue, and quality of life. Physical fitness will be measured by a cardiopulmonary exercise test, isometric muscle strength tests, and muscle power and endurance tests. Limiting factors will be identified via neurological, pulmonary, and cardiac evaluations and the assessment of body composition and muscle size. Semistructured, qualitative interviews, analyzed using systematic text condensation, will identify the perceived barriers to and facilitators of PA for survivors of childhood cancer. In WP 4, we will evaluate the feasibility of a 6-month personalized PA intervention with the involvement of local structures.

Results

Ethical approvals have been secured at all participating sites (Norwegian Regional Committee for Medical Research Ethics [2016/953 and 2018/739]; the Oslo University Hospital Data Protection Officer; equivalent institutions in Finland, Denmark [file H-19032270], Germany, and Switzerland [Ethics Committee of Northwestern and Central Switzerland, project ID: 2019-00410]). Data collection for WP 1 to 3 is complete. This will be completed by July 2022 for WP 4. Several publications are already in preparation, and 2 have been published.

Conclusions

The PACCS study will generate high-quality knowledge that will contribute to the development of an evidence-based PA intervention for young survivors of childhood cancer to improve their long-term care and health. We will identify physiological, psychological, and social barriers to PA that can be targeted in interventions with immediate benefits for young survivors of childhood cancer in need of rehabilitation.

International Registered Report Identifier (IRRID)

DERR1-10.2196/35838

Reference data on anthropometrics, aerobic fitness and muscle strength in young Norwegian men and women

Purpose

Anthropometrics, aerobic fitness and muscle strength are measured in one-third of all 18-year-old Norwegian men and women during yearly selection for compulsory military service. The large sample size and geographical representativity make these data valuable for reference. The main purpose of this study was to present reference data for anthropometrics and physical fitness in young Norwegian men and women.

Methods

All 154,659 subjects (66% men and 34% women, 17–21 years old) who completed physical examinations at conscript selection from 2011 to 2019 were included in the study. Body mass index (BMI) was calculated from height and weight measurements. Peak oxygen uptake (VO_2peak) was estimated from performance on a maximal treadmill test. Muscle strength was measured by isometric chest and leg press, or seated medicine ball throw, standing long jump and pull-ups.

Results

Mean BMI (SD) was 23.1 (3.4) and 22.9 (3.3) kg·m⁻² in men and women, respectively (P < 0.001), and 24% of men and 21% of women had a BMI ≥ 25 kg·m⁻². Estimated VO_2peak was 52.9 (4.6) and 42.7 (3.9) mL·kg⁻¹·min⁻¹ in men and women, respectively (P < 0.001). Men performed significantly better than women on all muscle strength tests, with corresponding effect sizes varying from 1.14 for isometric leg press to 2.96 for seated medicine ball throw.

Conclusion

The presented reference data on physical fitness in young Norwegian men and women can be used to evaluate population health, serve as reference material for future studies and describes sex differences in several physical fitness parameters.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00421-021-04784-4.

Temporal trends in physical activity levels across more than a decade - a national physical activity surveillance system among Norwegian children and adolescents

BACKGROUND

There is a scarcity of device measured data on temporal changes in physical activity (PA) in large population-based samples. The purpose of this study is to describe gender and age-group specific temporal trends in device measured PA between 2005, 2011 and 2018 by comparing three nationally representative samples of children and adolescents.

METHODS

Norwegian children and adolescents (6, 9 and 15-year-olds) were invited to participate in 2005 (only 9- and 15-year-olds), 2011 and 2018 through cluster sampling (schools primary sampling units). A combined sample of 9500 individuals participated. Physical activity was assessed by hip worn accelerometers, with PA indices including overall PA (counts per minute), moderate-to-vigorous intensity PA (MVPA), and PA guideline adherence (achieving on average ≥ 60 min/day of moderate-to-vigorous PA). Random-effects linear regressions and logistic regressions adjusted for school-level clusters were used to analyse temporal trends.

FINDINGS

In total, 8186 of the participating children and adolescents provided valid PA data. Proportions of sufficiently active 6-year-olds were almost identical in 2011 and 2018; boys 95% (95% CI: 92, 97) and 94% (95%CI: 92, 96) and girls 86% (95% CI: 83, 90) and 86% (95% CI: 82, 90). Proportions of sufficiently active 15-year-olds in 2005 and 2018 were 52% (95% CI: 46, 59) and 55% (95% CI: 48, 62) in boys, and 48% (95% CI: 42, 55) and 44% (95% CI: 37, 51) in girls, respectively, resulting from small differences in min/day of MVPA. Among 9-year-old boys and girls, proportions of sufficiently active declined between 2005 and 2018, from 90% (95% CI: 87, 93) to 84% (95% CI: 80, 87)) and 74% (95% CI: 69, 79) to 68% (95% CI: 64, 72), respectively. This resulted from 9.7 min/day less MVPA in boys (95% CI: - 14.8, - 4.7; p < 0.001) and 3.2 min/day less MVPA (95% CI: - 7.0, 0.7; p = 0.106) in girls.

CONCLUSIONS

PA levels have been fairly stable between 2005, 2011 and 2018 in Norwegian youth. However, the declining PA level among 9-year-old boys and the low proportion of 15-year-olds sufficiently active is concerning. To evaluate the effect of, and plan for new, PA promoting strategies, it is important to ensure more frequent, systematic, device-based monitoring of population-levels of PA.

The Effect of Inspiratory Muscle Warm-Up on VO2 Kinetics during Submaximal Rowing

The aim of the study was to investigate the effect of an inspiratory muscle warm-up on the VO₂ kinetics during submaximal intensity ergometer rowing. Ten competitive male rowers (age 23.1 ± 3.8 years; height 188.1 ± 6.3 cm; body mass 85.6 ± 6.6 kg) took part in this investigation. A submaximal constant intensity (90% P_VO2max) rowing test to volitional exhaustion was carried out twice with the standard rowing warm-up (Test 1) and with the standard rowing warm-up with additional specific inspiratory muscle warm-up of two sets of 30 repetitions at 40% maximal inspiratory pressure (Test 2). We found a significant correlation between time constant (τ₁) and the VO₂ value at 400 s in Test 1 (r = 0.78; p < 0.05); however, no correlation was found between those parameters in Test 2. In addition, we found a positive association between VO_2max from the incremental rowing test and τ₁ from Test 1 (r = 0.71; p < 0.05), whereas VO₂ did not correlate with τ₁ from Test 2. Adding inspiratory muscle warm-up of 40% maximal inspiratory pressure to regular rowing warm-up had no significant effect on oxygen consumption kinetics during submaximal rowing tests.

Effect of Sex, Body Mass Index and Physical Activity Level on Peak Oxygen Uptake Among 14-19 Years Old Adolescents

The aim was to describe longitudinal trends in peak oxygen uptake (VO_2peak) among 14- to 19-year-old adolescents in Norway, and to examine effects of sex, body mass index (BMI), and physical activity (PA) level on VO_2peak during adolescence. Of 124 invited students from two lower secondary schools in Norway, 116 eighth-grade students (61 boys and 55 girls; 14 years old at baseline) volunteered to participate. The study has a longitudinal design with 6 yearly repeated measures of body height and mass, VO_2peak and PA level. VO_2peak allometrically scaled to body mass raised to the power of 0.67 was measured using a walking or running incremental test on a treadmill, whereas PA level was self-reported. Among 696 possible observations, 555 (79.7%) were valid. Multiple linear regression and linear mixed model analyses were used to examine the associations between age, sex, BMI, PA level and VO_2peak. VO_2peak showed a non-linear pattern from age 14 to 19, with a distinct increase for boys peaking at age 17, while the results provide a flatter and more stable curve for girls. Sex, BMI and PA level together explained 43–71% of the variance in VO_2peak at the different age levels. Sex and PA level contributed independently to explain a significant proportion of the variance in VO_2peak at all measurement occasions, while BMI did not. Adjusted sex differences in VO_2peak increased over time, from 26.5 ml·kg^−0.67·min⁻¹ at age 14 to 55.5 ml·kg^−0.67·min⁻¹ at age 19. The independent contribution from PA level to the variance in VO_2peak increased from age 14 to 16 and then decreased. While PA level explained 32.5% of the total variance in VO_2peak for 16-year-olds, this number was 14% in 19-year-olds. In conclusion, aerobic power showed a non-linear pattern during adolescence, peaking at age 17. Sex and PA level explained a large proportion of the variance in VO_2peak, each of them being an independent contributor to VO_2peak. Aerobic power is linked to improved health and seems to depend largely on sex and PA level in adolescents, emphasizing the importance of maintaining a sufficient PA level during adolescence.

Resilience and lifestyle-related factors as predictors for health-related quality of life among early adolescents: a cross-sectional study

Objective

To examine whether lifestyle-related factors and resilience predict health-related quality of life (HRQoL) in a sample of early adolescents.

Methods

A total of 611 eighth grade pupils (response rate: 79%) participated in this cross-sectional study. The variables measured were physical activity (accelerometer), cardiorespiratory fitness (Andersen test) and a questionnaire assessing dietary habits, sleep disturbance, resilience (Resilience Scale for Adolescents) and HRQoL (KIDSCREEN-27).

Results

A total of 36% of the sample met the official recommendations of 60 minutes of daily physical activity. Univariate analysis identified physical activity, dietary habits, sleep disturbances, body mass index (BMI), cardiorespiratory fitness and resilience, but not sedentary time, as predictors of HRQoL. Multivariate regression analysis identified resilience as a positive predictor (β 0.18 to 0.27) of all HRQoL domains and sleep disturbance as a negative predictor (β −0.65 to −0.24) of four HRQoL domains. BMI (β = −0.27) and cardiorespiratory fitness (β = 0.021) were predictors of the HRQoL domain physical well-being. Adherence to dietary recommendations was both a positive and a negative predictor of HRQoL (β −0.45 to 0.59).

Conclusion

Resilience and sleep disturbances were the main predictors of HRQoL.

The multivariate physical activity signature associated with metabolic health in children and youth: An International Children's Accelerometry Database (ICAD) analysis

There is solid evidence for an association between physical activity and metabolic health outcomes in children and youth, but for methodological reasons most studies describe the intensity spectrum using only a few summary measures. We aimed to determine the multivariate physical activity intensity signature associated with metabolic health in a large and diverse sample of children and youth, by investigating the association pattern for the entire physical intensity spectrum. We used pooled data from 11 studies and 11,853 participants aged 5.8-18.4 years included in the International Children's Accelerometry Database. We derived 14 accelerometry-derived (ActiGraph) physical activity variables covering the intensity spectrum (from 0-99 to ≥8000 counts per minute). To handle the multicollinearity among these variables, we used multivariate pattern analysis to establish the associations with indices of metabolic health (abdominal fatness, insulin sensitivity, lipid metabolism, blood pressure). A composite metabolic health score was used as the main outcome variable. Associations with the composite metabolic health score were weak for sedentary time and light physical activity, but gradually strengthened with increasing time spent in moderate and vigorous intensities (up to 4000-5000 counts per minute). Association patterns were fairly consistent across sex and age groups, but varied across different metabolic health outcomes. This novel analytic approach suggests that vigorous intensity, rather than less intense activities or sedentary behavior, are related to metabolic health in children and youth.

Association between objectively measured physical activity and longitudinal changes in body composition in adolescents: the Tromsø study fit futures cohort

OBJECTIVES

Physical activity may be important in deterring the obesity epidemic. This study aimed to determine whether objectively measured physical activity in first year of upper secondary high school predicted changes in body composition over 2 years of follow-up in a cohort of Norwegian adolescents (n=431).

DESIGN

A longitudinal study of adolescents (mean age of 16 (SD 0.4) at baseline, 60.3% girls) participating in the Fit Futures studies 1 (2010-2011) and 2 (2012-2013).

SETTING

All eight upper secondary high schools in two municipalities in Northern Norway.

PARTICIPANTS

Students participating in both studies and under the age of 18 at baseline and with valid measurement of physical activity at baseline and body composition in both surveys.

PRIMARY AND SECONDARY OUTCOMES

Change in objectively measured body mass index and waist circumference and change in dual-energy X-ray absorptiometry measured fat mass index, lean mass index (LMI) and appendicular LMI (aLMI) between baseline and follow-up.

RESULTS

At baseline, boys had significantly higher physical activity volume (p=0.01) and spent on average of 6.4 (95% CI 2.1 to 10.6) more minutes in moderate-to-vigorous physical activity (MVPA) than girls (p<0.01). In girls, multivariate regression analyses showed that more sedentary time was negatively associated with changes in LMI (p<0.01) and aLMI (p<0.05), whereas more light activity had opposite effects on these measures (p<0.01 and p<0.05, respectively). No significant associations between measures of baseline physical activity and changes in body composition parameters were observed in boys.

CONCLUSIONS

In this cohort of Norwegian adolescents, sedentary and light physical activity was associated with changes in LMI and aLMI in girls, but not boys. Minutes spent in MVPA in first year of upper secondary high school was not associated with changes in measures of body composition in neither sex after 2 years.

Associations between Motor Competence, Physical Self-Perception and Autonomous Motivation for Physical Activity in Children

Research indicates that children and adolescents gradually participate less in physical activity with age. Several factors are associated with children's physical activity levels, such as motor performance, self-perception of athletic competence and motivation to physical activity. To gain a better understanding of the factors of importance for behavior related to an active lifestyle, the purpose of this study was to investigate the association between motor competence, physical self-perception and autonomous motivation and to examine to what extent this association may vary by sex. The sample consisted of 101 children, whose average age was 11.7 years (SD = 0.57), 53 boys and 48 girls. All subjects were measured on motor competence, physical self-perception and autonomous motivation for physical activity. The results indicate a low positive relationship between motor competence and physical self-perception for the entire sample and among girls. There is also a significant correlation between autonomous motivation and physical self-perception. No significant correlations were found between autonomous motivation and motor competence. The association between physical self-perception and autonomous motivation suggests that psychological factors play an important role in children's participation in physical activity.

Prevalence of accelerometer-measured physical activity in adolescents in Fit Futures - part of the Tromsø Study

BACKGROUND

Previous studies show large variations in physical activity (PA) levels among adolescents. However, the number of studies is limited and even fewer studies have assessed PA in adolescents by accelerometer devices. This study aimed to describe accelerometer-measured PA levels in adolescents in a population-based cohort in Northern Norway.

METHODS

In 611 students aged 16-17 years attending the Fit Futures Study, PA was measured by Actigraph GT3X for seven consecutive days. PA was expressed as total PA volume (counts per minute, CPM), time spent in intensity zones, steps per day, and fulfilment of WHO recommendation (i.e. accumulation of 60 min or more of at least moderate intensity PA per day). Potential correlates of PA such as sex, socioeconomic status, study program, self-perceived health, and PA variations by weekday versus weekend were also examined.

RESULTS

16% of the girls and 25% of the boys fulfilled current WHO-recommendations. Total PA volume (CPM) was higher in boys than in girls (353 (SD 130) versus 326 (SD 114) CPM, p < 0.05). PA levels differed with study program and increased with better self-perceived health, but were not associated with socioeconomic status. Both boys and girls were more active on weekdays than weekends (altogether; 350 (SD 124) versus 299 (SD 178) CPM, p < 0.05).

CONCLUSIONS

In this cohort of adolescents, less than 25% of 16-17-year-old boys and girls fulfilled the WHO recommendations. The levels of physical activity in 16-17-year-old adolescents are similar to previous data reported in adults.

Birth weight, cardiometabolic risk factors and effect modification of physical activity in children and adolescents: pooled data from 12 international studies

Objectives

Low and high birth weight is associated with higher levels of cardiometabolic risk factors and adiposity in children and adolescents, and increases the risk of cardiovascular diseases, obesity, and early mortality later in life. Moderate-to-vigorous physical activity (MVPA) is associated with lower cardiometabolic risk factors and may mitigate the detrimental consequences of high or low birth weight. Thus, we examined whether MVPA modified the associations between birth weight and cardiometabolic risk factors in children and adolescents.

Methods

We used pooled individual data from 12 cohort- or cross-sectional studies including 9,100 children and adolescents. Birth weight was measured at birth or maternally reported retrospectively. Device-measured physical activity (PA) and cardiometabolic risk factors were measured in childhood or adolescence. We tested for associations between birth weight, MVPA, and cardiometabolic risk factors using multilevel linear regression, including study as a random factor. We tested for interaction between birth weight and MVPA by introducing the interaction term in the models (birth weight x MVPA).

Results

Most of the associations between birth weight (kg) and cardiometabolic risk factors were not modified by MVPA (min/day), except between birth weight and waist circumference (cm) in children (p = 0.005) and HDL-cholesterol (mmol/l) in adolescents (p = 0.040). Sensitivity analyses suggested that some of the associations were modified by VPA, i.e., the associations between birth weight and diastolic blood pressure (mmHg) in children (p = 0.009) and LDL- cholesterol (mmol/l) (p = 0.009) and triglycerides (mmol/l) in adolescents (p = 0.028).

Conclusion

MVPA appears not to consistently modify the associations between low birth weight and cardiometabolic risk. In contrast, MVPA may mitigate the association between higher birth weight and higher waist circumference in children. MVPA is consistently associated with a lower cardiometabolic risk across the birth weight spectrum. Optimal prenatal growth and subsequent PA are both important in relation to cardiometabolic health in children and adolescents.

Changes in cardiorespiratory fitness through adolescence predict metabolic syndrome in young adults

BACKGROUND AND AIMS

Higher cardiorespiratory fitness (CRF) has been suggested to reduce the risk of metabolic syndrome (MetS). We aimed to longitudinally examine the changes of CRF on MetS and its risk factors from adolescence to adulthood.

METHODS AND RESULTS

At the age of 15 years, 1076 subjects were recruited from 2 cohorts. CRF was measured on a cycle ergometer. MetS was classified as having at least 3 of the following parameters above the threshold of risk factors: waist circumference, triglycerides, high-density lipoprotein cholesterol (HDL), high blood pressure (BP) and fasting glucose. In addition, insulin, total cholesterol and low-density lipoprotein cholesterol were measured and homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Persistently high, increasing, decreasing and persistently low CRF groups were formed according to change in CRF from adolescence to adulthood. Longitudinal increase in CRF was positively associated with change in HDL and negatively associated with change in insulin, HOMA-IR, triglycerides, BP and prevalence of MetS after adjustment for potential confounders. Subjects with persistently low CRF had 11.5- to 34.4-times higher risk of MetS at the age of 25 and 33 years compared to subjects with persistently high CRF and 14.6- to 15.9-times higher risk compared to the increasing CRF group.

CONCLUSION

Higher CRF is strongly related to lower values of MetS risk factors. Increasing CRF from adolescence to adulthood reduces the risk to have MetS later in adulthood. High CRF in adolescence that decreases during adulthood has similar risks to MetS compared to individuals with persistently low CRF.

Variations in accelerometry measured physical activity and sedentary time across Europe - harmonized analyses of 47,497 children and adolescents

Background

Levels of physical activity and variation in physical activity and sedentary time by place and person in European children and adolescents are largely unknown. The objective of the study was to assess the variations in objectively measured physical activity and sedentary time in children and adolescents across Europe.

Methods

Six databases were systematically searched to identify pan-European and national data sets on physical activity and sedentary time assessed by the same accelerometer in children (2 to 9.9 years) and adolescents (≥10 to 18 years). We harmonized individual-level data by reprocessing hip-worn raw accelerometer data files from 30 different studies conducted between 1997 and 2014, representing 47,497 individuals (2–18 years) from 18 different European countries.

Results

Overall, a maximum of 29% (95% CI: 25, 33) of children and 29% (95% CI: 25, 32) of adolescents were categorized as sufficiently physically active. We observed substantial country- and region-specific differences in physical activity and sedentary time, with lower physical activity levels and prevalence estimates in Southern European countries. Boys were more active and less sedentary in all age-categories. The onset of age-related lowering or leveling-off of physical activity and increase in sedentary time seems to become apparent at around 6 to 7 years of age.

Conclusions

Two third of European children and adolescents are not sufficiently active. Our findings suggest substantial gender-, country- and region-specific differences in physical activity. These results should encourage policymakers, governments, and local and national stakeholders to take action to facilitate an increase in the physical activity levels of young people across Europe.

Modeling the dose-response rate/associations between VO2max and self-reported Physical Activity Questionnaire in children and adolescents

Background

This study sought to explore the dose-response rate/association between aerobic fitness (VO2max) and self-reported physical activity (PA) and to assess whether this association varies by sex, age, and weight status.

Methods

VO2max was assessed using the 20-m shuttle-run test. PA was assessed using the Physical Activity Questionnaire (PAQ) for Adolescents (aged >11 years, PAQ-A) or for Children (aged ≤11 years, PAQ-C). The associations between VO2max and PAQ were analyzed using analysis of covariance (ANCOVA), adopting PAQ and PAQ2 as covariates but allowing the intercepts and slope parameters of PAQ and PAQ2 to vary with the categorical variables sex, age group, and weight status.

Results

ANCOVA identified a curvilinear association between VO2max and PAQ, with positive linear PAQ terms that varied for both sex and weight status but with a negative PAQ2 term of -0.39 (95% confidence interval (CI): -0.57 to -0.21) that was common for all groups in regard to age, sex, and weight status. These curvilinear (inverted U) associations suggest that the benefits of increasing PA (same dose) on VO2max is greater when children report lower levels of PA compared to children who report higher levels of PA. These dose-response rates were also steeper for boys and were steeper for lean children compared to overweight/obese children.

Conclusion

Health practitioners should be aware that encouraging greater PA (same dose) in inactive and underweight children will result in greater gains in VO2max (response) compared with their active and overweight/obese counterparts.

Gender-specific mediators of the association between parental education and adiposity among adolescents: the HEIA study

Identifying the mechanisms behind socioeconomic inequalities in adiposity among youth is vital for efforts aimed at combating these inequalities. The study explored whether a broad range of behavioral and familial factors mediated the associations between parental education and indicators of adiposity among adolescents. Baseline data from a school-based intervention study conducted in 2007 among 11-year-old adolescents were used. Anthropometric outcomes, physical activity and sedentary time among adolescents were objectively measured. Other behavioral variables and parental waist circumference were self-reported. Mediation analyses were conducted. Among boys, maternal waist circumference (WC), paternal WC and TV viewing mediated 16%, 11.5% and 13% of the association between parental education and adolescent WC. The respective proportions when body fat percentage was used as the outcome variable were 22.5%, 16% and 21%. Among girls, maternal and paternal WC mediated 20% and 14% of the association between parental education and WC. The respective proportions when body fat percentage was used as the outcome variable were 14% and 10%. Other included variables did not play any mediating role. Parental WC was found to be a mediator of socioeconomic differences in adiposity in both genders; underlying mechanisms were however not investigated. Among boys, reducing TV time could contribute to the reduction of social inequalities in adiposity.

Participation in Organized Sports and Self-Organized Physical Activity: Associations with Developmental Factors

Engagement in organized sports is associated with developmental factors, such as, healthy growth, cognitive abilities, psychological well-being and lower substance use. Research also suggest that the spontaneous free play that characterises self-organized physical activity (PA) provides young people with opportunities to learn social skills, such as self-regulation and conflict-resolution skills. We assessed associations between participation in the two activity types and several demographics along with developmental factors (e.g., body mass index (BMI)). Data was from a representative sample of 2060 students attending 38 schools in Norway (mean age (M_age) = 15.29, standard deviation (SD) = 1.51; 52% females). Results indicated that while engagement in organized sports was more related to developmental factors, relative to self-organized PA, engaging concurrently in both activities for at least an hour a week was more developmentally beneficial than engaging only in one for the same amount of time. Thus, PA programmes for students will enhance their effectiveness if they focus on structured activities but also self-organized activities where students can coordinate themselves.

Physical activity in patients with oligo- and polyarticular juvenile idiopathic arthritis diagnosed in the era of biologics: a controlled cross-sectional study

BACKGROUND

Knowledge about objectively measured levels of physical activity (PA) and PA participation (included facilitators and barriers for PA) in patients with juvenile idiopathic arthritis (JIA) diagnosed in the era of biologics is limited. We aimed to compare objectively measured PA in patients with oligo- and polyarticular JIA diagnosed in the biologic era with controls and to examine associations between PA and disease variables; furthermore, to explore participation in PA, physical education (PE) and facilitators and barriers for PA participation in patients and controls.

METHODS

The study cohort included 60 patients (30 persistent oligo JIA/30 poly-articular disease) and 60 age- and sex-matched controls. Age range was 10-16 years and 83% were female. PA was measured with accelerometry for seven consecutive days. Disease activity, current treatment, disease duration, functional ability, pain and fatigue were assessed. Structured interviews were applied to explore participation in PA and PE, and PA facilitators and barriers.

RESULTS

Patients spent less time in daily vigorous PA than controls, (mean(SE) 21(2) min vs. 26(2) min, p = 0.02), while counts per minute (cpm), steps daily, sedentary time and light and moderate PA did not differ. No differences were found between JIA subgroups. The use of biologic medication was associated with higher cpm and lower sedentary time. Most patients and controls participated in organized or unorganized PA and PE, and enjoyment was the most reported facilitator for PA participation. More patients than controls reported pain as a PA barrier.

CONCLUSION

The PA levels and participation in patients with oligo- and polyarticular JIA are mostly comparable to controls, but patients still need to be encouraged to increase vigorous PA. Enjoyment is the most important facilitator for PA participation in patients with JIA.

Objectively assessed moderate-to-vigorous physical activity levels among primary school children in Norway: The Health Oriented Pedagogical Project (HOPP)

AIMS

The objective was to investigate moderate-to-vigorous physical activity levels (MVPA) of primary school children at baseline of the Health Oriented Pedagogical Project (HOPP), Norway.

METHODS

Data on 2123 children aged 6-12 years were included for analysis (75% participation rate). Average minutes per day in MVPA was objectively measured using accelerometry based on seven-day averages. The sample was analysed for age-, sex-, socioeconomic-, and season-related patterns. A linear regression investigated the moderating effect of these factors as well as body mass index and waist circumference.

RESULTS

Some 86.5% of the sample had at least 60 min/day MVPA, averaging 90.7 min/day. The main differences in daily averages were between age groups 6½-9 and 10-12 ( p < .05). Boys (95.8 min/day, 95% CI: 94.1-97.5) were more active than girls (85.6 min/day, 95% CI: 83.9-87.2) in all age groups ( p < .0001). MVPA was lower by 3.5 min ( p < .0001) per additional year of age in the linear regression (R² = 0.176) and was reduced by 20 min less per day in MVPA in the winter months compared with the summer months ( p < .0001).

CONCLUSIONS

Physical activity levels are already in decline from 6-7 years old and are likely to continue to decline into adolescence. Interventions must therefore focus on primary school children.

Improved cognitive performance in preadolescent Danish children after the school-based physical activity programme "FIFA 11 for Health" for Europe - A cluster-randomised controlled trial

OBJECTIVE

Recent studies have shown promising effects of physical activity on cognitive function, but there is a need to investigate this link in real-life settings such as schools. Hence, the objective of the present pilot study was to investigate whether the school-based physical activity programme "FIFA 11 for Health" for Europe could improve cognitive performance in preadolescent Danish children.

METHODS

The pilot study used an 11-week cluster-randomised intervention study design. School classes were randomly assigned to either a control group (CG) (n = 93 children, age = 11.8, s = 0.2 years), which performed the obligatory daily school-based physical activity (5 × 45 minutes per week); or an intervention group (IG) (n = 838 children, age = 11.9, s = 0.4 years), which substituted 2 × 45 minutes per week of the daily school physical activity with the "FIFA 11 for Health" for Europe programme. The programme combines small-sided football games, drills and health education. Cognitive performance was evaluated at baseline and follow-up.

RESULTS

The IG improved their cognitive performance compared to the CG for psychomotor function (56, s_x^- = 22 ms, p < .001), attention (39, s_x^- = 17 ms, p = .012) and working memory (79, s_x^- = 35 ms, p = .020).

CONCLUSION

This pilot study provides evidence that the school-based physical activity programme "FIFA 11 for Health" for Europe can improve cognitive performance in preadolescent Danish schoolchildren. Future studies should attempt to disentangle the effects of "FIFA 11 for Health" for Europe on cognitive performance by investigating the characteristics of the programme's physical activity.

Understanding differences between summer vs. school obesogenic behaviors of children: the structured days hypothesis

BACKGROUND

Although the scientific community has acknowledged modest improvements can be made to weight status and obesogenic behaviors (i.e., physical activity, sedentary/screen time, diet, and sleep) during the school year, studies suggests improvements are erased as elementary-age children are released to summer vacation. Emerging evidence shows children return to school after summer vacation displaying accelerated weight gain compared to the weight gained occurring during the school year. Understanding how summer days differ from when children are in school is, therefore, essential.

DISCUSSION

There is limited evidence on the etiology of accelerated weight gain during summer, with few studies comparing obesogenic behaviors on the same children during school and summer. For many children, summer days may be analogous to weekend days throughout the school year. Weekend days are often limited in consistent and formal structure, and thus differ from school days where segmented, pre-planned, restrictive, and compulsory components exist that shape obesogenic behaviors. The authors hypothesize that obesogenic behaviors are beneficially regulated when children are exposed to a structured day (i.e., school weekday) compared to what commonly occurs during summer. This is referred to as the 'Structured Days Hypothesis' (SDH). To illustrate how the SDH operates, this study examines empirical data that compares weekend day (less-structured) versus weekday (structured) obesogenic behaviors in U.S. elementary school-aged children. From 190 studies, 155 (~80%) demonstrate elementary-aged children's obesogenic behaviors are more unfavorable during weekend days compared to weekdays.

CONCLUSION

In light of the SDH, consistent evidence demonstrates the structured environment of weekdays may help to protect children by regulating obesogenic behaviors, most likely through compulsory physical activity opportunities, restricting caloric intake, reducing screen time occasions, and regulating sleep schedules. Summer is emerging as the critical period where childhood obesity prevention efforts need to be focused. The SDH can help researchers understand the drivers of obesogenic behaviors during summer and lead to innovative intervention development.

Executive Functions Do Not Mediate Prospective Relations between Indices of Physical Activity and Academic Performance: The Active Smarter Kids (ASK) Study

Changes in cognitive function induced by physical activity have been proposed as a mechanism for the link between physical activity and academic performance. The aim of this study was to investigate if executive function mediated the prospective relations between indices of physical activity and academic performance in a sample of 10-year-old Norwegian children. The study included 1,129 children participating in the Active Smarter Kids (ASK) trial, followed over 7 months. Structural equation modeling (SEM) with a latent variable of executive function (measuring inhibition, working memory, and cognitive flexibility) was used in the analyses. Predictors were objectively measured physical activity, time spent sedentary, aerobic fitness, and motor skills. Outcomes were performance on national tests of numeracy, reading, and English (as a second language). Generally, indices of physical activity did not predict executive function and academic performance. A modest mediation effect of executive function was observed for the relation between motor skills and academic performance. Trial registration: Clinicaltrials.gov registry, trial registration number: NCT02132494.

No difference in the level of physical activity between children who have or have never sustained a fracture

This study investigates whether children with an acute fracture have a different level of physical activity compared to children who have never sustained a fracture, as measured by the Physical Activity Questionnaire for older children (PAQ-C). The PAQ-C scores of 683 children (295 girls) aged 6-12 years (mean age 9.4 years) who presented to our institution with an acute fracture were compared to the PAQ-C scores of 151 random children (81 girls) aged 6-12 years (mean 9.1 years) in the same area who had never sustained a fracture. Multivariate regression analysis was employed, controlling for age and gender. The mean PAQ-C score of the children who presented to the institution with an acute fracture was 2.85 (95% confidence interval [CI], 2.80-2.91). For the children who had never sustained a fracture, the mean PAQ-C score was 2.78 (95% CI, 2.69-2.87). If there is a true difference in the level of physical activity between children who have or have never sustained a fracture, the PAQ-C questionnaire is not sensitive enough to identify it.

Physical Activity in School-Aged Children with Asthma in an Urban City of Taiwan

BACKGROUND

It has been reported that physical activity is limited in children with asthma. The aims of this study were to compare and quantify the physical activity levels between asthmatic children and their healthy peers. Factors associated with limitation of physical activity in asthmatic children were also investigated.

METHODS

A total of 120 asthmatic children and 262 age-matched healthy controls were enrolled in this study. Clinical phenotype including severity and lung function were obtained from medical records. A questionnaire addressing physical activity, asthma diagnosis, symptoms, parental health beliefs, physician's advice and, community resources was accomplished by children and their parents. The physical activity levels of children with and without asthma were compared. Factors that might limit the activity level were analyzed.

RESULTS

Children with asthma were less active than their peers. The significant difference was between normal controls and moderate-to-severe asthmatic children, but not children with mild asthma. Among children with asthma, physical activity was associated with the severity level but not parental health beliefs, physician's advice, or the convenience for physical activity. Children with moderate or severe persistent asthma were more likely to be inactive.

CONCLUSION

Children with asthma had a lower level of physical activity, particularly those with moderate-to-severe asthma. To achieve an appropriate level of physical activity, improvement of asthma management and control is considered important.

Sex-specific associations of moderate and vigorous physical activity with physical fitness in adolescents

The present study examined the sex-specific associations of moderate and vigorous physical activity (VPA) with physical fitness in 300 Japanese adolescents aged 12-14 years. Participants were asked to wear an accelerometer to evaluate physical activity (PA) levels of various intensities (i.e. moderate PA (MPA), 3-5.9 metabolic equivalents (METs); VPA, ≥6 METs; moderate to vigorous PA (MVPA), ≥3 METs). Eight fitness items were assessed (grip strength, bent-leg sit-up, sit-and-reach, side step, 50 m sprint, standing long jump, handball throw, and distance running) as part of the Japanese standardised fitness test. A fitness composite score was calculated using Japanese fitness norms, and participants were categorised according to their score from category A (most fit) to category E (least fit), with participants in categories D and E defined as having low fitness. It was found that for boys, accumulating more than 80.7 min/day of MVPA may reduce the probability of low fitness (odds ratio (ORs) [95% confidence interval (CI)] = 0.17 [0.06-0.47], p = .001). For girls, accumulating only 8.4 min of VPA could reduce the likelihood of exhibiting low fitness (ORs [95% CI] = 0.23 [0.05-0.89], p = .032). These results reveal that there are sex-specific differences in the relationship between PA and physical fitness in adolescents, suggesting that sex-specific PA recommendation may be needed to improve physical fitness in adolescents.

Effect of inspiratory muscle warm-up on submaximal rowing performance

Performing inspiratory muscle warm-up might increase exercise performance. The aim of this study was to investigate the impact of inspiratory muscle warm-up to submaximal rowing performance and to find if there is an effect on lactic acid accumulation and breathing parameters. Ten competitive male rowers aged between 19 and 27 years (age, 23.1 ± 3.8 years; height, 188.1 ± 6.3 cm; body mass, 85.6 ± 6.6 kg) were tested 3 times. During the first visit, maximal inspiratory pressure (MIP) assessment and the incremental rowing test were performed to measure maximal oxygen consumption and maximal aerobic power (Pamax). A submaximal intensity (90% Pamax) rowing test was performed twice with the standard rowing warm-up as test 1 and with the standard rowing warm-up and specific inspiratory muscle warm-up as test 2. During the 2 experimental tests, distance, duration, heart rate, breathing frequency, ventilation, peak oxygen consumption, and blood lactate concentration were measured. The only value that showed a significant difference between the test 1 and test 2 was breathing frequency (52.2 ± 6.8 vs. 53.1 ± 6.8, respectively). Heart rate and ventilation showed a tendency to decrease and increase, respectively, after the inspiratory muscle warm-up (p < 0.1). Despite some changes in respiratory parameters, the use of 40% MIP intensity warm-up is not suggested if the mean intensity of the competition is at submaximal level (at approximately 90% maximal oxygen consumption). In conclusion, the warm-up protocol of the respiratory muscles used in this study does not have a significant influence on submaximal endurance performance in highly trained male rowers.

The effect of physical activity on mental health among adolescents with and without self-reported visual impairment: The Young-HUNT Study, Norway

The purpose was to study the effect of physical activity (PA) on mental health according to self-reported vision categories among adolescents. The study was conducted in Nord-Trøndelag, Norway, during the period 1995–1997, with a follow-up 4 years later. Self-reported measurements were used to assess PA and vision at baseline, and mental health problems and well-being at follow-up. The main linear regression analyses included 1417 adolescents between the age of 12 and 17 years, of which 46 had reported visual impairment. Among those reporting no impairment, conducting <1 day per week of PA was significantly associated with having lower levels of well-being at follow-up compared to those conducting ⩾1 day of PA. Among those reporting visual impairment, the mental health benefits of conducting weekly PA compared with conducting non-weekly PA were observed only among those who were more emotionally unstable or introvert at baseline. In conclusion, further longitudinal studies are warranted to examine whether the mental health responses of PA may be dependent on the adolescent’s vision status.

Comparison of three generations of ActiGraph activity monitors under free-living conditions: do they provide comparable assessments of overall physical activity in 9-year old children?

Background

A recent review concludes that the agreement of data across ActiGraph accelerometer models for children and youth still is uncertain. The aim of this study was to evaluate the agreement of three generations of ActiGraph accelerometers in children in a free-living condition.

Methods

Sixteen 9-year-olds wore the ActiGraph AM7164, GT1M and GT3X+ simultaneously for three consecutive days. We compared mean counts per minute (mcpm) and time spent at different intensities from the three generations of monitors, and the agreement of outputs were evaluated by intra-class correlation coefficients (ICC) and Bland-Altman plots.

Results

The ICC for mcpm was 0.985 (95% CI = 0.898, 0.996). We found a relative difference of 11.6% and 9.8% between the AM7164 and the GT1M and AM7164 and the GT3X+, respectively. The relative difference between mcpm assessed by the GT1M and GT3X+ was 1.7%. The inter-generation differences varied in magnitude and direction across intensity levels, with the largest difference found in the highest intensities.

Conclusion

We found that the ActiGraph model AM7164 yields higher outputs of mean physical activity intensity (mcpm) than the models GT1M and GT3X+ in children in free-living conditions. The generations GT1M and GT3X+ provided comparable outputs. The differences between the old and the newer monitors were more complex when investigating time spent at different intensities. Comparisons of data assessed by the AM7164 with data assessed by newer generations ActiGraphs should be done with caution.

Assessment of physical activity and energy expenditure: an overview of objective measures

The ability to assess energy expenditure (EE) and estimate physical activity (PA) in free-living individuals is extremely important in the global context of non-communicable diseases including malnutrition, overnutrition (obesity), and diabetes. It is also important to appreciate that PA and EE are different constructs with PA defined as any bodily movement that results in EE and accordingly, energy is expended as a result of PA. However, total energy expenditure, best assessed using the criterion doubly labeled water (DLW) technique, includes components in addition to physical activity energy expenditure, namely resting energy expenditure and the thermic effect of food. Given the large number of assessment techniques currently used to estimate PA in humans, it is imperative to understand the relative merits of each. The goal of this review is to provide information on the utility and limitations of a range of objective measures of PA and their relationship with EE. The measures discussed include those based on EE or oxygen uptake including DLW, activity energy expenditure, physical activity level, and metabolic equivalent; those based on heart rate monitoring and motion sensors; and because of their widespread use, selected subjective measures.

Accelerometer-determined physical activity and self-reported health in a population of older adults (65-85 years): a cross-sectional study

Background

The link between physical activity (PA) and prevention of disease, maintenance of independence, and improved quality of life in older adults is supported by strong evidence. However, there is a lack of data on population levels in this regard, where PA level has been measured objectively. The main aims were therefore to assess the level of accelerometer-determined PA and to examine its associations with self-reported health in a population of Norwegian older adults (65–85 years).

Methods

This was a part of a national multicenter study. Participants for the initial study were randomly selected from the national population registry, and the current study included those of the initial sample aged 65–85 years. The ActiGraph GT1M accelerometer was used to measure PA for seven consecutive days. A questionnaire was used to register self-reported health. Univariate analysis of variance with Bonferroni adjustments were used for comparisons between multiple groups.

Results

A total of 560 participants had valid activity registrations. Mean age (SD) was 71.8 (5.6) years for women (n = 282) and 71.7 (5.2) years for men (n = 278). Overall PA level (cpm) differed considerably between the age groups where the oldest (80–85 y) displayed a 50% lower activity level compared to the youngest (65–70 y). No sex differences were observed in overall PA within each age group. Significantly more men spent time being sedentary (65–69 and 70–74 years) and achieved more minutes of moderate to vigorous PA (MVPA) (75–79 years) compared to women. Significantly more women (except for the oldest), spent more minutes of low-intensity PA compared to men. PA differed across levels of self-reported health and a 51% higher overall PA level was registered in those, with “very good health” compared to those with “poor/very poor health”.

Conclusion

Norwegian older adults PA levels differed by age. Overall, the elderly spent 66% of their time being sedentary and only 3% in MVPA. Twenty one percent of the participants fulfilled the current Norwegian PA recommendations. Overall PA levels were associated with self-reported health.

Adiposity, aerobic fitness, muscle fitness, and markers of inflammation in children

PURPOSE

The purpose of this study was to describe levels of inflammation markers in Norwegian children and to examine the associations of adiposity, aerobic fitness, and muscle fitness with markers of inflammation.

METHODS

In 2005-2006, 1467 nine-year-olds were randomly selected from all regions in Norway. The participation rate was 89%. The inflammatory markers evaluated included C-reactive protein (CRP), leptin, adiponectin, plasminogen activator inhibitor-1, tumor necrosis factor-α, hepatocyte growth factor, resistin, and interleukin-6. We assessed muscular strength by measuring explosive, isometric, and endurance strength. Aerobic fitness was measured directly during a maximal cycle ergometer test. Adiposity was expressed as waist circumference (WC).

RESULTS

The girls had significantly higher levels of CRP, leptin, adiponectin, and resistin and lower levels of tumor necrosis factor-α compared with the boys. We observed a graded association of CRP and leptin levels across quintiles of WC, aerobic fitness, and muscle fitness (P ≤ 0.001 for all participants). The regression analyses revealed that WC, aerobic fitness, and muscle fitness were independently associated with the CRP (WC β = 0.158, P < 0.001; aerobic fitness β = -0.190, P < 0.001; muscle fitness β = -0.122, P < 0.002) after adjustments for sex, age, Tanner pubertal stage, and the other independent variables. The same pattern was observed for leptin levels (WC β = 0.406, P < 0.001; aerobic fitness β = -0.298, P < 0.001; muscle fitness β = -0.064, P < 0.036).

CONCLUSIONS

These data represent a reference material with respect to inflammatory markers. Our results show that adiposity, aerobic fitness, and muscle fitness were independently associated with the CRP and leptin levels.

Ace I/D polymorphism is associated with habitual physical activity in pubertal boys

We investigated the association between the angiotensin I-converting enzyme (ACE) gene insertion (I)/deletion (D) polymorphism and physical activity levels in boys at early pubertal stage (calendar age 12.04 ± 0.77 years). Body composition by DXA, pubertal stage and cardiovascular fitness on cycle ergometer were measured in addition to 7-day accelerometry. DNA was separated from the whole blood. Sedentary behaviour level was significantly lower in DD subjects compared to I allele carriers. A significant main effect of the D allele was found on total physical activity (F 1,256 = 5,453; p = 0.020; η (2) = 0.021] and on light physical activity (F 1,256 = 4.74; p = 0.030; η (2) = 0.018). Adding screen time as a covariate did not change ACE I/D polymorphism effect on total physical activity levels (F 2,256 = 3,326; p = 0.041; η (2) = 0.025). Carriers of the D allele had significantly higher light physical activity (F 1,256 = 4,710; p = 0.031; η (2) = 0.20), with screen time as covariate. In conclusion, ACE gene has a significant effect on sedentary, light and total physical activity levels in healthy 12-year-old boys.

Screen time viewing behaviors and isometric trunk muscle strength in youth

PURPOSE

The objective of this study was to examine the association of screen time viewing behavior with isometric trunk muscle strength in youth.

METHODS

A cross-sectional study was carried out including 606 adolescents (14-16 yr old) participating in the Danish European Youth Heart Study, a population-based study with assessments conducted in either 1997/1998 or 2003/2004. Maximal voluntary contractions during isometric back extension and abdominal flexion were determined using a strain gauge dynamometer, and cardiorespiratory fitness (CRF) was obtained using a maximal cycle ergometer test. TV viewing time, computer use, and other lifestyle behaviors were obtained by self-report. Analyses of association of screen use behaviors with isometric trunk muscle strength were carried out using multivariable adjusted linear regression.

RESULTS

The mean (SD) isometric strength was 0.87 (0.16) N·kg-1. TV viewing, computer use, and total screen time use were inversely associated with isometric trunk muscle strength in analyses adjusted for lifestyle and sociodemographic factors. After further adjustment for CRF and waist circumference, associations remained significant for computer use and total screen time, but TV viewing was only marginally associated with muscle strength after these additional adjustments (-0.05 SD (95% confidence interval, -0.11 to 0.005) difference in strength per 1 h·d-1 difference in TV viewing time, P = 0.08). Each 1 h·d-1 difference in total screen time use was associated with -0.09 SD (95% confidence interval, -0.14 to -0.04) lower isometric trunk muscle strength in the fully adjusted model (P = 0.001). There were no indications that the association of screen time use with isometric trunk muscle strength was attenuated among highly fit individuals (P = 0.91 for CRF by screen time interaction).

CONCLUSIONS

Screen time use was inversely associated with isometric trunk muscle strength independent of CRF and other confounding factors.

Normative data of BMI and physical fitness in a Norwegian sample of early adolescents

Aim: The purpose of the present study was to 1) provide normative data quantifying the physical fitness level and body mass index of 13–15-year-old Norwegian adolescents using a multi-component fitness assessment, and 2) compare the physical fitness of Norwegian teenagers with available European and International fitness data. Methods: 1059 adolescents (529 males, 530 females) from 12 public schools in Kristiansand were invited to testing at age 13, 14, and 15 years (Grades 8–10). Test participation was 75%–80%. The participants performed objectively anthropometrical measures (height and weight) and six field-based physical fitness tests. Results and Conclusions: As expected, sex differences in physical fitness expanded from age 13 to 15. Strength and power increased more in males than females. Aerobic capacity increased slightly in males while remaining stable or tending to decline in females. Balance and gross motor coordination improved identically in males and females from age 13 to 15. Compared to European and International reference data, the sample performed superior in endurance and balance, slightly above median in lower-body strength, but inferior in flexibility.

Independent and combined association of muscle strength and cardiorespiratory fitness in youth with insulin resistance and β-cell function in young adulthood: the European Youth Heart Study

OBJECTIVE

To examine the independent and combined association of isometric muscle strength of the abdomen and back and cardiorespiratory fitness (CRF) in youth with indices of glucose metabolism in young adulthood among boys and girls from the European Youth Heart Study.

RESEARCH DESIGN AND METHODS

We used data from a population-based prospective cohort study among youth followed up for up to 12 years (n = 317). In youth, maximal voluntary contractions during isometric back extension and abdominal flexion were determined using a strain-gauge dynamometer and CRF was obtained from a maximal cycle ergometer test. Insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR]) and β-cell function (homeostasis model assessment of β-cell function [HOMA-B]) were estimated from fasting serum insulin and glucose that were obtained in youth and at follow-up in young adulthood.

RESULTS

For each 1-SD difference in isometric muscle strength (0.16 N/kg) in youth, fasting insulin, HOMA-IR, and HOMA-B in young adulthood changed by -11.3% (95% CI -17.0 to -5.2), -12.2% (-18.2 to -5.7), and -8.9% (-14.4 to -3.0), respectively, in young adulthood after adjustment for CRF and personal lifestyle and demographic factors. Results for CRF were very similar in magnitude, and the magnitude of associations for both exposures was unchanged with additional adjustment for general or abdominal adiposity in youth. Combined associations of muscle strength and CRF with fasting insulin, HOMA-IR, and HOMA-B were additive, and adolescents in the highest sex-specific tertile for both isometric muscle strength and CRF had the lowest levels of these glucose metabolism outcomes.

CONCLUSIONS

Increasing muscle strength and CRF should be targets in youth primordial prevention strategies of insulin resistance and β-cell dysfunction.

Cross sectional analysis of the association between mode of school transportation and physical fitness in children and adolescents

Objective

To investigate the associations between body composition, cardiorespiratory and muscular fitness in relation to travel mode to school in children and adolescents.

Method

Children and adolescents from 40 elementary schools and 23 high schools representing all regions in Norway were invited to participate in the study. Anthropometry, cardiorespiratory and muscular fitness were tested at the school location. Questionnaires were used in order to register mode of transport to school, age, gender and levels of leisure time physical activity.

Results

A total of 1694 (i.e. 60% of all invited participants) children and adolescents at a mean age of 9.6 and 15.6 respectively (SD = 0.4 for both groups) were analyzed for associations with physical fitness variables. Males cycling to school had lower sum of skin folds than adolescents walking to school. Higher cardiorespiratory fitness in adolescents and male cyclists compared to walkers and passive commuters were observed. Among children, cycling and walking to school, higher isometric muscle endurance in the back extensors compared to passive commuters was observed.

Conclusion

Based on this national representative cross-sectional examination of randomly selected children and adolescents there is evidence that active commuting, especially cycling, is associated with a favourable body composition and better cardiorespiratory and muscular fitness as compared to passive commuting.

Peak oxygen uptake and physical activity in 13- to 18-year-olds: the Young-HUNT study

PURPOSE

The present study describes the distribution of cardiorespiratory fitness (VO2peak) in a large sample of healthy adolescents and the associations between VO2peak, self-reported physical activity, and a selection of conventional markers for future cardiovascular health.

METHODS

In a substudy of the Young-HUNT study in Norway, 570 adolescents (289 girls and 281 boys) 13–18 yr. old were tested for directly measured VO2peak. Blood pressure, resting heart rate, height, weight, and waist circumference was measured by standardized procedures. Data about physical activity and pubertal development were obtained using self-administered questionnaires. General linear modeling and ANOVA were used to examine the relationships between VO2peak and age, physical activity, and cardiovascular risk factors.

RESULTS

The mean T SD VO2peak was 183.9 +/- 24.6 mL x kg(-0.67) x min(-1) (49.2 mL x kg(-0.67) x min(-1)) in girls and 235.1 +/- 35.3 mL x kg(-0.67) x min(-1) (59.5 mL x kg(-0.67) x min(-1)) in boys. Absolute VO2peak (L x min(-1)) was consistently higher in older age groups in both sexes (P trend < 0.001). VO2peak allometrically scaled to body mass (mL x kg(-0.67) x min(-1)) was similar across the age groups in girls (i.e., difference between 13- to 14-yr-olds and 17- to 18-yr-olds = -3.2 mL x kg(-0.67) x min(-1), 95% confidence interval = 3.8 to -10.1) and slightly higher in the older age groups in boys (i.e., difference between 13- to 14-yr-olds and 15- to 16-yr-olds = -31.0 mL x kg(-0.67) x min(-1), 95% confidence interval = -22.0 to -40.1). Physical activity was positively associated with VO2peak in all sex and age groups. Quartiles of VO2peak were inversely associated with resting heart rate (P trend = 0.004) in both sexes and body mass index (P trend = 0.004) and waist circumference (P trend = 0.006) in boys.

CONCLUSION

Although VO2peak was generally high across the age groups, VO2peak was higher in physically active adolescents of both sexes and physical activity in accordance with the recommended level may be sufficient to maintain or even increase VO2peak through adolescence.

Effects of a 20-month cluster randomised controlled school-based intervention trial on BMI of school-aged boys and girls: the HEIA study

Background

School-based interventions that target prevention of overweight and obesity in children have been tested with mixed results. Thus, successful interventions are still called for. The aim of the present study was to investigate effects of a multicomponent school-based intervention programme targeting physical activity, sedentary and dietary behaviours on anthropometric outcomes.

Methods

A 20-month intervention was evaluated in a cluster randomised, controlled study of 1324 11-year-olds. Outcome variables were body mass index (BMI), BMI-for-age z-score (BMIz), waist circumference (WC), waist-to-height ratio (WTHR) and weight status (International Obesity Task Force's cut-offs). Weight, height and WC were measured objectively; pubertal status was self-reported and parental education was self-reported by the parents. Intervention effects were determined by one-way analysis of covariance and logistic regression, after checking for clustering effects of school, and moderating effects of gender, pubertal status and parental education.

Results

Beneficial effects were found for BMI (p=0.02) and BMIz (p=0.003) in girls, but not in boys. While a beneficial effect was found for BMI (p=0.03) in participants of parents reporting a high level of education, a negative effect was found for WTHR in participants with parents reporting a low level of education (p=0.003). There were no intervention effects for WC and weight status.

Conclusions

A multicomponent 20-month school-based intervention had a beneficial effect on BMI and BMIz in adolescent girls, but not in boys. Furthermore, children of higher educated parents seemed to benefit more from the intervention, and this needs attention in future interventions to avoid further increase in social inequalities in overweight and obesity.

Level of physical activity among children and adolescents in Europe: a review of physical activity assessed objectively by accelerometry

This study explored the proportion of European youth who are sufficiently active according to physical activity (PA) recommendations, based exclusively on objective assessment through accelerometers. A systematic electronic search of studies published up to March 2012 was conducted. PubMed was used to identify accelerometry-assessed PA studies that involved European youth. Within the 131 European studies, only 35 clearly reported the proportion of youth meeting the PA recommendations. Different thresholds lying between 1000 and 4000 counts/min (cpm) were used to define moderate-to-vigorous PA (MVPA). Overall, up to 100% of youth may be sufficiently active when using a threshold of approximately >1000-1500 cpm. With the most cited cut-off point (i.e. >2000 cpm), up to 87% of European youth might be considered physically active with reference to the current recommendations. Alternatively, with a cut-off point >3000 cpm, no more than 3-5% of them appeared to achieve these recommendations. The large discrepancy in outcomes released by accelerometer data is mainly due to the variety of cut-off points for MVPA among youth, hindering the definition of a clear goal towards PA promotion in Europe. Standardization of methods is urgently required.

Muscle strength in youth and cardiovascular risk in young adulthood (the European Youth Heart Study)

BACKGROUND

Whether muscle strength in youth is related to cardiovascular risk later in life independent of cardiorespiratory fitness is unclear.

METHODS

We examined the independent association of isometric muscle strength in youth with cardiovascular risk factors in young adulthood using data from the Danish European Youth Heart Study; a population-based prospective cohort study among boys and girls (n=332) followed for up to 12 years. In youth maximal voluntary contractions during isometric back extension and abdominal flexion were determined using a strain-gauge dynamometer and cardiorespiratory fitness was obtained from a maximal cycle ergometer test. Cardiovascular risk factors were obtained in youth and in young adulthood. Associations were examined using multivariable-adjusted regression models including major confounding factors.

RESULTS

Each 1 SD difference in isometric muscle strength in youth (0.17 N/kg) was inversely associated with body mass index (BMI; -0.60 kg/m(2), 95% CI -0.97 to -0.22), triglyceride (-0.09 mmol/l, 95% CI -0.16 to -0.02), diastolic blood pressure (BP) (-1.22 mm Hg, 95% CI -2.15 to -0.29) and a composite cardiovascular risk factor score (-0.61 SD, 95% CI -1.03 to -0.20) in young adulthood in multivariable-adjusted analyses including fitness. Associations to triglyceride, diastolic BP and the cardiovascular risk factor score remained with additional adjustment for waist circumference or BMI. Each 1 SD difference in isometric muscle strength in youth was significantly associated with 0.59 (95% CI 0.40 to 0.87) lower odds of general overweight/obesity in young adulthood (p=0.007) and was marginally associated with incident raised BP, raised triglyceride and low high-density lipoprotein cholesterol.

CONCLUSIONS

This study suggests that greater isometric muscle strength in youth is associated with lower levels of cardiovascular risk factors in young adulthood independent of fitness, adiposity and other confounding factors.

Intervention effects on physical activity: the HEIA study - a cluster randomized controlled trial

Background

Although school-based interventions to promote physical activity in adolescents have been suggested in several recent reviews, questions have been raised regarding the effects of the strategies and the methodology applied and for whom the interventions are effective. The aim of the present study was to investigate effects of a school-based intervention program: the HEalth in Adolescents (HEIA) study, on change in physical activity, and furthermore, to explore whether potential effects varied by gender, weight status, initial physical activity level and parental education level.

Methods

This was a cluster randomized controlled 20 month intervention study which included 700 11-year-olds. Main outcome-variable was mean count per minute (cpm) derived from ActiGraph accelerometers (Model 7164/GT1M). Weight and height were measured objectively. Adolescents reported their pubertal status in a questionnaire and parents reported their education level on the consent form. Linear mixed models were used to test intervention effects and to account for the clustering effect of sampling by school.

Results

The present study showed an intervention effect on overall physical activity at the level of p = 0.05 with a net effect of 50 cpm increase from baseline to post intervention in favour of the intervention group (95% CI −0.4, 100). Subgroup analyses showed that the effect appeared to be more profound among girls (Est 65 cpm, CI 5, 124, p = 0.03) and among participants in the low-activity group (Est 92 cpm, CI 41, 142, p < 0.001), as compared to boys and participants in the high-activity group, respectively. Furthermore, the intervention affected physical activity among the normal weight group more positively than among the overweight, and participants with parents having 13–16 years of education more positively than participants with parents having either a lower or higher number of years of education. The intervention seemed to succeed in reducing time spent sedentary among girls but not among boys.

Conclusions

A comprehensive but feasible, multi-component school-based intervention can affect physical activity patterns in adolescents by increasing overall physical activity. This intervention effect seemed to be more profound in girls than boys, low-active adolescents compared to high-active adolescents, participants with normal weight compared to the overweight, and for participants with parents of middle education level as opposed to those with high and low education levels, respectively. An implementation of the HEIA intervention components in the school system may have a beneficial effect on public health by increasing overall physical activity among adolescents and possibly among girls and low-active adolescents in particular.