Physical Activity Levels and Domains Assessed by Accelerometry in German Adolescents from GINIplus and LISAplus

The Effectiveness of Interventions to Reduce Sedentary Time in Different Target Groups and Settings in Germany: Systematic Review, Meta-Analysis and Recommendations on Interventions

BACKGROUND

Sedentary behavior is an important risk factor for several chronic diseases and is associated with an increased risk of mortality. We assessed the effectiveness of interventions to reduce sedentary time in Germany and provide recommendations on interventions to reduce sedentary time in children and adults.

METHODS

We comprehensively searched PubMed, Web of Science and the German Clinical Trials Register up to April 2022 for intervention studies targeting sedentary behavior in Germany. We performed a systematic review and qualitative synthesis of the interventions and a meta-analysis in children.

RESULTS

We included 15 studies comprising data from 4588 participants. The results of included primary studies in adults and children showed inconsistent evidence regarding change in sedentary time, with a majority of studies reporting non-significant intervention effects. The meta-analysis in children showed an increase in sedentary time for children in the control and intervention groups.

CONCLUSION

We found inconsistent evidence regarding the effectiveness of interventions to reduce time spent sedentary and our meta-analysis showed an increase in sedentary time in children. For children, we recommend physical and social environment interventions with an active involvement of families. For adults, we recommend physical environment interventions, such as height-adjustable desks at work.

Physical activity and sedentary time of youth in structured settings: a systematic review and meta-analysis

BACKGROUND

Structured settings, such as school, childcare, afterschool programs, summer camps, and physical activity/sport programs are crucial to promoting physical activity (PA) opportunities and reducing sedentary (ST) for children and adolescents. However, little is known about how much PA and ST children and adolescents accumulate in structured settings. The aim of this study is to conduct a systematic review and meta-analysis of the absolute amount of time youth spend physically active and sedentary in different structured settings (Prospero number: 42018111804).

METHODS

Observational and experimental/quasi-experimental studies (baseline data only) with full-text available, written in English and published in a peer-reviewed journal, reporting the total amount of objectively measured PA (light, moderate, vigorous, and/or total physical activity) and/or time spent ST during structured settings among youth (3 to 18 years) were eligible. Adjusted meta-analysis was conducted to estimate the pooled mean of time spent in PA and ST, by settings and sex.

RESULTS

A total of 187 studies (childcare n=60; school n=91; afterschool programs n=14; summer camp n=4; and Physical activity/ sport programs n=18) from 30 countries (47.9% United States), representing 74,870 youth (mean age 8.6 years old) were included. Overall, there was a high variation between studies in outcomes and settings. The meta-analyses revealed, on average, youth spend 221.8 minutes (36.7 min/hour) in ST and 32.1 minutes (5.1 min/hour) in MVPA during childcare hours, and 223.9 minutes (36.7min/hour) in ST and 27.8 min (4.4 min/hour) in MVPA at school. Relatively, youth are engaged in more MVPA in afterschool programs (11.7 min/hour), PA/ sport programs (20.9 min/hour), and summer camps (6.4 min/hour), when compared to childcare and school.

CONCLUSION

Total PA accumulated during childcare and MVPA accumulated during schools hours were close to recommendations, despite high proportion of ST. Afterschool programs, summer camp and PA/ sport programs are important settings that can contribute to daily PA and reduced ST. Ensuring all youth have access to these structured settings may be an important step forward for public health.

Objective Measures to Assess Active Commuting Physical Activity to School in Young People: A Systematic Review Protocol and Practical Considerations

There are no systematic reviews that have identified the existing studies assessing active commuting physical activity (PA) to and from (to/from) school using objective measures, as well as the contribution of both walking and cycling to/from school to PA levels. To fill this gap in the literature, this systematic review will aim (a) to identify existing studies that assess active commuting PA to/from school with objective measures in young people and to examine the contribution of walking and cycling to/from school to PA levels, and (b) to propose an appropriate methodology and practical considerations to assess active commuting PA to/from school based on the studies identified. The review protocol was registered in PROSPERO (CRD42020162004). We will conduct a systematic search up to 2020 in five databases: PubMed, Web of Science, SPORTdiscuss, Cochrane Library, and National Transportation Library. Both the risk of bias and the quality of the identified studies will be evaluated through different instruments according to the design of each study. This systematic review will help to choose the most appropriate objective measures to assess active commuting PA to/from school and to promote walking and cycling to/from school to increase PA levels.

Association between objectively assessed physical activity and sleep quality in adolescence. Results from the GINIplus and LISA studies

STUDY OBJECTIVES

Population-based studies on the association of objectively assessed physical activity (PA) with sleep among adolescents are rare. We examined this association by applying accelerometry and accounting for the day-by-day variability.

METHODS

Accelerometers (Actigraph GT3X) were worn for one week by 1223 participants during the 15-year follow-up of the German birth cohorts (German infant study on the Influence of Nutrition Intervention plus air pollution and genetics on allergy development, GINIplus) and (Influence of Lifestyle factors on the development of the Immune System and Allergies in East and West Germany, LISA) to measure PA and sleep. PA was categorised into sedentary, lifestyle and moderate-to-vigorous physical activity (MVPA) referring to Sasaki and Romanzini. Sleep was analysed according to the algorithm developed by Sadeh. Sleep quality was represented by sleep efficiency (SE), sleep onset latency (SOL) and time awake per hour after sleep onset (TAPH). Sleep and activity were additionally reported by diaries. Linear and generalized mixed-effects-models with logit-link with subject specific random intercepts were used stratified by sex and adjusted for confounding variables.

RESULTS

Physical activity appears to be associated only with sleep quality the following night. Among female participants, SE improved (β = 0.12 [95% CI = (0.05; 0.18)]) per 10 minutes increase of MVPA. SOL decreased (OR = 0.83 [95% CI = (0.69; 0.99)]) among male participants with at least 60 min of MVPA per day. Engaging in leisure sport MVPA was associated with higher SE among female (β = 0.70 [95% CI = (0.22; 1.17)]) and male participants (β = 0.76 [95% CI = (0.18; 1.34)]). Also, TAPH among female (β = -0.37 [95% CI = (-0.65; -0.09)]) and SOL among male subjects (OR = 0.70 [95% CI = (0.57; 0.85)]) decreased. Increasing lifestyle activity was related to longer SOL among female (OR = 1.36 [95% CI = (1.15; 1.62)]) and male subjects (OR = 1.32 [95% CI = (1.10; 1.58)]).

CONCLUSIONS

In this large population-based sample of German adolescents MVPA and leisure sport improved short term sleep quality, supporting regular PA in adolescents for their health benefit.

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.

Physical activity levels and sedentary time during school hours of 6th-grade girls in Germany

Aim

Regular physical activity and low levels of sedentary time have positive health effects on youth, and data are needed to base public health recommendations on. Here, findings of device-based physical activity and sedentary time in sixth graders are presented. Data below are presented as mean (SD).

Subject and methods

Three hundred and eight sixth-grade girls [11.6 (0.6) years] from the CReActivity study in Germany wore accelerometers (ActiGraph GT3X) for 7 consecutive days. Moderate to vigorous physical activity (MVPA), light physical activity (LPA), and sedentary time (ST) was obtained during school days with a focus on recess times.

Results

Girls spent 79.9 (23.2) minutes in MVPA and 9.4 (1.2) hours in ST during schooldays, of which 20.5 (8.2) minutes and 3.8 (0.4) hours respectively were accumulated during school hours. On average, students had 35.4 (4.5) minutes break, of which 6.3 (3.2) minutes (17.8%) were spent in MVPA activity and 16.5 (6.2) minutes (46.6%) in ST.

Conclusion

School setting is an important factor for physical activity and sedentary time. Therefore policy, curriculums, and school environment should promote physical activity und reduce sedentary time during school hours.

Sports Contribute to Total Moderate to Vigorous Physical Activity in School Children

INTRODUCTION

A third of all children spend at least 60 min·d in moderate to vigorous physical activity (MVPA) as recommended by the World Health Organization. We investigated the distribution of objectively measured physical activity (PA) intensities achieved by schoolchildren during physical education (PE) and organized youth sports (OYS) and the contribution of PE and OYS to the achievement of the PA recommendations.

METHODS

In two surveys, PA of 396 children was measured using accelerometry during typical school weeks. Proportions (%) of sedentary behavior, light PA, and MVPA per day and particularly during sports were assessed in children 6-17 yr old. Adjusted odds ratios (AOR) were calculated to analyze the association between frequency (d·wk) and duration (min·wk) of PE and OYS and meeting the PA recommendations.

RESULTS

Average proportions of MVPA during PE and OYS ranged between 15% and 31%. Between 68% and 74% of children (6-10 yr) and between 27% and 37% of adolescents (11-17 yr) met the PA recommendations. In both age-groups, PE and OYS on at least 2 d·wk were both significantly associated with meeting the PA recommendations (AOR for PE = 3.60, 95% confidence interval [CI] = 2.05-6.31; AOR for OYS = 3.83, 95% CI = 2.09-6.99), compared with no PE or no OYS in that week. Likewise, significant AOR values were found for >90 min of PE per week (AOR = 3.48, 95% CI = 2.03-5.98) and >120 min of OYS per week (AOR = 3.72, 95% CI = 2.01-6.89), compared with no PE or no OYS in that week, respectively.

CONCLUSION

Schoolchildren spent less than one-third of PE and OYS in MVPA. PE and OYS were found to support children and adolescents to engage sufficiently in MVPA as recommended by the World Health Organization.

What is the contribution of each physical activity domain to total physical activity in adolescents?

Abstract The present study aimed to verify the contribution of different physical activity domains to “total physical activity” in Brazilian adolescents. This is a cross-sectional study using secondary data from the third edition of the National School Health Survey - PeNSE, 2015. The sample consisted of 100,497 adolescents of both sexes enrolled in the 9th grade of elementary schools. A linear regression model was used to verify how much each domain contributed to total physical activity, considering gender, type of municipality and region. The domain with the largest contribution to “total physical activity” regardless of sociodemographic and environmental variables was “extra-school physical activity” (R2 = 0.60), followed by “active commuting” (R2 = 0.34), and finally “Physical Education classes” (R2 = 0.23). The contribution of the different domains varied by gender, type of municipality and region, and it was concluded that “extra-school physical activity” make the greatest contribution to “total physical activity”, followed by “active commuting” and “Physical Education classes”. In addition, variation was observed in the contribution of domains by gender, type of municipality and region.

Diverging effects of premature birth and bronchopulmonary dysplasia on exercise capacity and physical activity - a case control study

Background

Extreme prematurity has been associated with exercise intolerance and reduced physical activity. We hypothesized that children with bronchopulmonary dysplasia (BPD) would be especially affected based on long-term lung function impairments. Therefore, the objective of this study was to compare exercise capacity and habitual physical activity between children born very and extremely preterm with and without BPD and term-born children.

Methods

Twenty-two school-aged children (aged 8 to 12 years) born with a gestational age < 32 weeks and a birthweight < 1500 g (9 with moderate or severe BPD (=BPD), 13 without BPD (=No-BPD)) and 15 healthy term-born children (=CONTROL) were included in the study. Physical activity was measured by accelerometry, lung function by spirometry and exercise capacity by an incremental cardiopulmonary exercise test.

Results

Peak oxygen uptake was reduced in the BPD-group (83 ± 11%predicted) compared to the No-BPD group (91 ± 8%predicted) and the CONTROL group (94 ± 9%predicted). In a general linear model, variance of peak oxygen uptake was significantly explained by BPD status and height but not by prematurity (p < 0.001).

Compared to CONTROL, all children born preterm spent significantly more time in sedentary behaviour (BPD 478 ± 50 min, No-BPD 450 ± 52 min, CONTROL 398 ± 56 min, p < 0.05) and less time in moderate-to-vigorous-physical activity (BPD 13 ± 8 min, No-BPD 16 ± 8 min, CONTROL 33 ± 16 min, p < 0.001). Prematurity but not BPD contributed significantly to explained variance in a general linear model of sedentary behaviour and likewise moderate-to-vigorous-physical activity (p < 0.05 and p < 0.001 respectively).

Conclusion

In our cohort, BPD but not prematurity was associated with a reduced exercise capacity at school-age. However, prematurity regardless of BPD was related to less engagement in physical activity and more time spent in sedentary behaviour. Thus, our findings suggest diverging effects of prematurity and BPD on exercise capacity and physical activity.

The relationship between transport-to-school habits and physical activity in a sample of New Zealand adolescents

OBJECTIVES

Adolescents using active transport (AT) to school have higher levels of physical activity (PA) compared with motorized transport (MT) users. This study compared school day and weekend day PA in adolescents using AT, MT, or combined AT and MT (AT + MT) to travel to school.

METHODS

Adolescents (n = 314; age: 14.7 ± 1.4 years; 32.8% boys) from Dunedin (New Zealand) wore an accelerometer for 7 days and completed a self-reported survey regarding mode of transport to school (73 AT, 56 AT + MT, and 185 MT). Data were analyzed using t tests, analysis of variance, and χ ² tests.

RESULTS

Although the proportion of adolescents meeting PA guidelines significantly differed among transport groups (AT, 47.9%; AT + MT, 46.4%; MT, 33.5%; p = 0.048; overall, 39.2%), the observed differences were due mainly to girls. Compared with MT, AT and AT + MT engaged in more moderate-to-vigorous PA (MVPA) per day (AT: 61.2 ± 23.2 min; AT + MT: 59.6 ± 21.7 min; MT: 52.5 ± 19.6 min; p = 0.004; p < 0.001, adjusted for gender), per school day and before school. Immediately after school (15:00-16:00), AT engaged in significantly more MVPA compared with AT + MT and MT. No differences in MVPA between the groups were observed in the late afternoon/early evening period during school days or on weekend days.

CONCLUSION

Compared with MT users, adolescent girls using AT or AT + MT accumulated more MVPA during school commute time. AT + MT to school is also a plausible way to increase adolescent girls' PA when AT only is not feasible.

Dietary saturated fat and low-grade inflammation modified by accelerometer-measured physical activity in adolescence: results from the GINIplus and LISA birth cohorts

BACKGROUND

Saturated fatty acids (SFA) have been reported to promote inflammation. Nevertheless, evidence linking dietary SFA and low-grade inflammation in adolescents is scarce and inconsistent. The modulatory role of physical activity (PA) on fat metabolism and inflammation may provide a potential explanation. Thus, we assessed the association of dietary SFA with high-sensitivity C-reactive protein (hsCRP), a marker of low-grade inflammation, in 15-year-olds, and evaluated possible interactions between dietary SFA and different levels of PA.

METHODS

Children participating in the 15-year follow-ups of the GINIplus and LISA German birth cohort studies were included (N = 824). SFA intake was estimated by means of a food frequency questionnaire and PA recorded by accelerometers. Average daily minutes of PA were classified into "sedentary", "light" and "moderate-to-vigorous" (MVPA), using Freedson's cut-offs. HsCRP concentrations were measured in serum and categorized into 3 sex-specific levels (below detection limit (I), above 75th percentile (III), in between (II)). Sex-stratified cross-sectional associations between SFA and hsCRP were assessed using multinomial logistic regression, adjusting for potential confounders. Interaction terms were included between SFA and the different PA levels; and if significant interactions were observed, analyses stratified by tertiles of the relevant PA levels were performed. Relative risk ratios (RRR) and 95% confidence intervals (95%CI) were presented for a 1% increase in SFA.

RESULTS

An inverse association was observed between SFA intake and hsCRP (II vs. I) in males (RRR = 0.85 [95%CI = 0.76;0.96], p = 0.008), whereas no significant association was observed in females. A significant interaction was observed with "sedentary" and "light" PA but not with MVPA in both sexes (p < 0.05). Stratified analyses indicated a significant inverse association between SFA and medium hsCRP levels in males in the highest light PA tertile (hsCRP II vs. I: 0.67 [0.517;0.858], p = 0.002).

CONCLUSION

Our findings do not support a detrimental role of dietary SFA in low-grade inflammation among adolescents. In males, higher dietary SFA was associated with lower hsCRP, although this should be interpreted in the context of possibly correlated nutrients. Children spending the most time in light PA drove the observed inverse association, suggesting a synergistic effect of SFA and lifestyle PA in the resultant inflammatory response.

Prediction of lung function using handgrip strength in healthy young adults

Positive association between physical activity and spirometry has been reported to be possibly attributed to handgrip strength (HGS), particularly in the elderly. However, the nature of the association between HGS and lung function in young adults is still unclear. This study investigated the prediction of lung function using HGS in young adults. A cross-sectional analytical study was carried out on four hundred (400) apparently healthy medical students who are aged 16-30 years. Handgrip strength (dominant and nondominant) and lung function (FEV1 , FVC and PEFR) of these students were assessed using Jamar dynamometer and a portable spirometer, respectively. Data were analyzed using inferential statistics. Independent t-test showed that the mean values of HGS and lung function of the males were significantly higher than the females (P < 0.0005). The relationship between HGS and lung function indices was significant (P < 0.0005) in all the participants but strongest for FEV1 (r = 0.64). The regression analysis showed that in addition to gender and height, HGS was a significant (P < 0.0005) predictor of lung function. Regression equations were also proposed for the prediction of these lung function indices using HGS, gender and height. This study is the first to report HGS as a significant predictor of pulmonary function in healthy young adults living in a low-resource country. Hence, its use could enhance medical practice in being an indicator of lung function status in healthy young adults.

Better lung function with increased handgrip strength, as well as maximum oxygen uptake, in congenital heart disease across the lifespan

Background

The respiratory benefits of muscle strength are well-known in heart-healthy populations, but recommendations and research often focus instead on aerobic fitness (peak oxygen uptake) or total activity. Independent benefits of strength thus may be underestimated, especially in congenital heart disease where perceived dangers of certain types of exercise may outweigh perceived benefits. To assess whether it is plausible that pulmonary benefits of strength in heart-healthy populations also apply in congenital heart disease, we simultaneously correlated these patients’ lung function with fitness, strength, and cardiac diagnosis.

Methods

Lung function (forced expiratory volume in one second percentage predicted (FEV1%pred)) was modeled as function of handgrip strength, congenital heart disease diagnosis, peak oxygen uptake and the interactions of handgrip with sex and diagnosis in 538 Germans (58% male, ages 6–82 years) in linear models corrected for age, sex, height and weight. Congenital heart disease diagnoses were: complex cyanotic; Fallot/Truncus arteriosus communis (common arterial trunk) (TAC); shunts; transposition of the great arteries (TGA); left heart; and other/none.

Results

Each kg of handgrip was associated with 0.74% higher FEV1%pred ( p < 0.001) and handgrip explained almost 10% of variance in FEV1%pred. While some groups had higher FEV1%pred than others ( p for global null <0.0001), all experienced similar associations with strength ( p for interaction with handgrip >0.10 for both sex and diagnosis.) Correction for peak oxygen uptake eliminated the association with congenital heart disease, but not handgrip.

Conclusion

Strength was associated with better lung function in all ages even after correction for peak oxygen uptake, regardless of sex and congenital heart disease. This suggests that strength may be at least as important for lung function as aerobic fitness. Heart-safe strength training may improve pulmonary function in congenital heart disease.

Uni- and triaxial accelerometric signals agree during daily routine, but show differences between sports

Accelerometers objectively monitor physical activity, and ongoing research suggests they can also detect patterns of body movement. However, different types of signal (uniaxial, captured by older studies, vs. the newer triaxial) and or/device (validated Actigraph used by older studies, vs. others) may lead to incomparability of results from different time periods. Standardization is desirable. We establish whether uniaxial signals adequately monitor routine activity, and whether triaxial accelerometry can detect sport-specific variations in movement pattern. 1402 adolescents wore triaxial Actigraphs (GT3X) for one week and diaried sport. Uni- and triaxial counts per minute were compared across the week and between over 30 different sports. Across the whole recording period 95% of variance in triaxial counts was explained by the vertical axis (5th percentile for R², 91%). Sport made up a small fraction of daily routine, but differences were visible: even when total acceleration was comparable, little was vertical in horizontal movements, such as ice skating (uniaxial counts 41% of triaxial) compared to complex movements (taekwondo, 55%) or ambulation (soccer, 69%). Triaxial accelerometry captured differences in movement pattern between sports, but so little time was spent in sport that, across the whole day, uni- and triaxial signals correlated closely. This indicates that, with certain limitations, uniaxial accelerometric measures of routine activity from older studies can be feasibly compared to triaxial measures from newer studies. Comparison of new studies based on raw accelerations to older studies based on proprietary devices and measures (epochs, counts) will require additional efforts which are not addressed in this paper.

Association of Dietary Fatty Acids with Blood Lipids is Modified by Physical Activity in Adolescents: Results from the GINIplus and LISA Birth Cohort Studies

The role of consuming different types of fatty acids (FA) at the expense of carbohydrates (CHO), on the blood lipid profile of adolescents is largely unknown, as is the modulating effect of different levels of physical activity (PA). Children from the GINIplus and LISA birth cohorts, with complete data on dietary FA (assessed by food-frequency questionnaires), objectively-measured PA (assessed by accelerometers) and blood lipids (lipoprotein cholesterol and triglycerides) at age 15 years, were included (N = 837). Sex-stratified associations between dietary FA and blood lipids were assessed by linear regression in substitution models which represented isocaloric replacements of CHO with saturated FA (SFA), monounsaturated FA (MUFA), n-3 polyunsaturated FA (PUFA) or n-6 PUFA. To assess the interactions with PA, analyses were then performed stratified by tertiles of different PA levels (sedentary, lifestyle, moderate-to-vigorous (MVPA)). Both sexes presented a significant inverse association between MUFA and triglycerides, and females a direct association between n-3 PUFA and high-density lipoprotein. Stratifying by PA tertiles, associations were mainly restricted to participants with the lowest levels of lifestyle PA, or the highest time spent sedentary. The effects of dietary FA on the lipid profile vary in an activity-specific manner, emphasizing possible synergistic roles of diet and PA.

Handgrip strength is associated with improved spirometry in adolescents

Introduction

Pulmonary rehabilitation, including aerobic exercise and strength training, improves function, such as spirometric indices, in lung disease. However, we found spirometry did not correlate with physical activity (PA) in healthy adolescents (Smith ERJ: 42(4), 2016). To address whether muscle strength did, we measured these adolescents’ handgrip strength and correlated it with spirometry.

Methods

In 1846 non-smoking, non-asthmatic Germans (age 15.2 years, 47% male), we modeled spirometric indices as functions of handgrip strength by linear regression in each sex, corrected for factors including age, height, and lean body mass.

Results

Handgrip averaged 35.4 (SD 7.3) kg in boys, 26.6 (4.2) in girls. Spirometric volumes and flows increased linearly with handgrip. In boys each kg handgrip was associated with about 28 mL greater FEV1 and FVC; 60 mL/sec faster PEF; and 38 mL/sec faster FEF2575. Effects were 10–30% smaller in girls (all p<0.0001) and stable when Z-scores for spirometry and grip were modeled, after further correction for environment and/or other exposures, and consistent across stages of puberty.

Conclusions

Grip strength was associated with spirometry in a cohort of healthy adolescents whose PA was not. Thus, research into PA’s relationship with lung function should consider strength as well as total PA. Strength training may benefit healthy lungs; interventions are needed to prove causality.

Accelerometric estimates of physical activity vary unstably with data handling

Background

Because of unreliable self-report, accelerometry is increasingly used to objectively monitor physical activity (PA). However, results of accelerometric studies vary depending on the chosen cutpoints between activity intensities. Population-specific activity patterns likely affect the size of these differences. To establish their size and stability we apply three sets of cutpoints, including two calibrated to a single reference, to our accelerometric data and compare PA estimates.

Methods

1402 German adolescents from the GINIplus and LISAplus cohorts wore triaxial accelerometers (Actigraph GT3x) for one week (mean 6.23 days, 14.7 hours per day) at the hip. After validation of wear, we applied three sets of cutpoints for youth, including the most common standard (Freedson, 2005) and two calibrated to a single reference, (Romanzini uni- and triaxial, from Romanzini, 2014) to these data, estimating daily sedentary, light, moderate, vigorous and moderate-to-vigorous PA (MPA, VPA, MVPA). Stability of differences was assessed by comparing Romanzini’s two sets of cutpoints.

Results

Relative agreement between cutpoints was closer for activity of lower intensities (largest difference for sedentary behaviour 9%) but increased for higher intensities (largest difference for light activity 40%, MPA 102%, VPA 88%; all p<0.01). Romanzini’s uniaxial and triaxial cutpoints agreed no more closely with each other than with Freedson’s.

Conclusions

Estimated PA differed significantly between different sets of cutpoints, even when those cutpoints agreed perfectly on another dataset (i.e. Romanzini’s.) This suggests that the detected differences in estimated PA depend on population-specific activity patterns, which cannot be easily corrected for: converting activity estimates from one set of cutpoints to another may require access to raw data. This limits the utility of accelerometry for comparing populations in place and time. We suggest that accelerometric research adopt a standard for data processing, and apply and present the results of this standard in addition to those from any other method.

Automatic machine-learning based identification of jogging periods from accelerometer measurements of adolescents under field conditions

Background

Assessment of health benefits associated with physical activity depend on the activity duration, intensity and frequency, therefore their correct identification is very valuable and important in epidemiological and clinical studies. The aims of this study are: to develop an algorithm for automatic identification of intended jogging periods; and to assess whether the identification performance is improved when using two accelerometers at the hip and ankle, compared to when using only one at either position.

Methods

The study used diarized jogging periods and the corresponding accelerometer data from thirty-nine, 15-year-old adolescents, collected under field conditions, as part of the GINIplus study. The data was obtained from two accelerometers placed at the hip and ankle. Automated feature engineering technique was performed to extract features from the raw accelerometer readings and to select a subset of the most significant features. Four machine learning algorithms were used for classification: Logistic regression, Support Vector Machines, Random Forest and Extremely Randomized Trees. Classification was performed using only data from the hip accelerometer, using only data from ankle accelerometer and using data from both accelerometers.

Results

The reported jogging periods were verified by visual inspection and used as golden standard. After the feature selection and tuning of the classification algorithms, all options provided a classification accuracy of at least 0.99, independent of the applied segmentation strategy with sliding windows of either 60s or 180s. The best matching ratio, i.e. the length of correctly identified jogging periods related to the total time including the missed ones, was up to 0.875. It could be additionally improved up to 0.967 by application of post-classification rules, which considered the duration of breaks and jogging periods. There was no obvious benefit of using two accelerometers, rather almost the same performance could be achieved from either accelerometer position.

Conclusions

Machine learning techniques can be used for automatic activity recognition, as they provide very accurate activity recognition, significantly more accurate than when keeping a diary. Identification of jogging periods in adolescents can be performed using only one accelerometer. Performance-wise there is no significant benefit from using accelerometers on both locations.

Physical activity levels, duration pattern and adherence to WHO recommendations in German adults

BACKGROUND

Intensity and duration of physical activity are associated with the achievement of health benefits. Our aim was to characterize physical activity behavior in terms of intensity, duration pattern, and adherence to the WHO physical activity recommendations in a population-based sample of adults from southern Germany. Further, we investigated associations between physical activity and sex, age, and body mass index (BMI), considering also common chronic diseases.

METHODS

We analyzed 475 subjects (47% males, mean age 58 years, range 48-68 years) who wore ActiGraph accelerometers for up to seven days. Measured accelerations per minute obtained from the vertical axis (uniaxial) and the vector magnitude of all three axes (triaxial) were classified as sedentary, light or moderate-to-vigorous physical activity (MVPA) according to predefined acceleration count cut-offs. The average minutes/day spent in each activity level per subject served as outcome. Associations of sex, age, BMI, and seven chronic diseases or health limitations, with the activity levels were analyzed by negative binomial regression.

RESULTS

Most of the wear time was spent in sedentarism (median 61%/day), whereas the median time spent in MVPA was only 3%, with men achieving more MVPA than women (35 vs. 28 minutes/day, p<0.05). Almost two thirds of MVPA was achieved in short bouts of less than 5 minutes, and 35% of the subjects did not achieve a single 10-minute bout. Hence, only 14% adhered to the WHO recommendation of 2.5 hours of MVPA/week in at least 10-minute bouts. Females, older subjects and obese subjects spent less time in MVPA (p<0.05), but no clear association with hypertension, asthma, diabetes, chronic obstructive pulmonary disease, anxiety/depression, pain or walking difficulties was observed in regression analyses with MVPA as outcome.

CONCLUSIONS

Activity behavior among middle-aged German adults was highly insufficient, indicating a further need for physical activity promotion in order to gain health benefits.

Asthma and Rhinitis Are Associated with Less Objectively-Measured Moderate and Vigorous Physical Activity, but Similar Sport Participation, in Adolescent German Boys: GINIplus and LISAplus Cohorts

INTRODUCTION

Physical activity (PA) protects against most noncommunicable diseases and has been associated with decreased risk of allergic phenotype, which is increasing worldwide. However, the association is not always present; furthermore it is not clear whether it is strongest for asthma, rhinitis, symptoms of these, or atopic sensitization; which sex is most affected; or whether it can be explained by either avoidance of sport or exacerbation of symptoms by exercise. Interventions are thus difficult to target.

METHODS

PA was measured by one-week accelerometry in 1137 Germans (mean age 15.6 years, 47% boys) from the GINIplus and LISAplus birth cohorts, and modeled as a correlate of allergic symptoms, sensitization, or reported doctor-diagnosed asthma or rhinitis.

RESULTS

8.3% of children had asthma, of the remainder 7.9% had rhinitis, and of the remainder 32% were sensitized to aero-allergens (atopic). 52% were lung-healthy controls. Lung-healthy boys and girls averaged 46.4 min and 37.8 min moderate-to-vigorous PA per day, of which 14.6 and 11.4 min was vigorous. PA in allergic girls was not altered, but boys with asthma got 13% less moderate and 29% less vigorous PA, and those with rhinitis with 13% less moderate PA, than lung-healthy boys. Both sexes participated comparably in sport (70 to 84%). Adolescents with wheezing (up to 68%, in asthma) and/or nose/eye symptoms (up to 88%, in rhinitis) were no less active.

CONCLUSIONS

We found that asthma and rhinitis, but not atopy, were independently associated with low PA in boys, but not in girls. These results indicate that allergic boys remain a high-risk group for physical inactivity even if they participate comparably in sport. Research into the link between PA and allergy should consider population-specific and sex-specific effects, and clinicians, parents, and designers of PA interventions should specifically address PA in allergic boys to ensure full participation.

Physical Activity Levels and Domains Assessed by Accelerometry in German Adolescents from GINIplus and LISAplus

BACKGROUND

Physical activity (PA) is a well-known and underused protective factor for numerous health outcomes, and interventions are hampered by lack of objective data. We combined accelerometers with diaries to estimate the contributions to total activity from different domains throughout the day and week in adolescents.

METHODS

Accelerometric and diary data from 1403 adolescents (45% male, mean age 15.6 ± 0.5 years) were combined to evaluate daily levels and domains of sedentary, light, and moderate-to-vigorous activity (MVPA) during a typical week. Freedson's cutoff points were applied to determine levels of activity. Total activity was broken down into school physical education (PE), school outside PE, transportation to school, sport, and other time.

RESULTS

About 2/3 of adolescents' time was spent sedentary, 1/3 in light activity, and about 5% in MVPA. Boys and girls averaged 46 (SD 22) and 38 (23) minutes MVPA per day. Adolescents were most active during leisure sport, spending about 30% of it in MVPA, followed by PE (about 20%) transport to school (14%) and either school class time or other time (3%). PE provided 5% of total MVPA, while leisure sport provided 16% and transportation to school 8%. School was the most sedentary part of the day with over 75% of time outside PE spent sedentary.

CONCLUSIONS

These German adolescents were typical of Europeans in showing low levels of physical activity, with significant contributions from leisure sport, transportation and school PE. Leisure sport was the most active part of the day, and participation did not vary significantly by sex, study center (region of Germany) or BMI. Transportation to school was frequent and thus accounted for a significant fraction of total MVPA. This indicates that even in a population with good access to dedicated sporting activities, frequent active transportation can add significantly to total MVPA.