Cardiorespiratory fitness has declined among French children since 1999, although the decline appears to be getting smaller.

BACKGROUND: Cardiorespiratory fitness (CRF) is a strong marker of current and future health. The aim of this study was to assess the national temporal trends in CRF for French children and adolescents between 1999 and 2022. METHODS: CRF data were obtained from several cross-sectional studies on 15 420 (51.1% boys) French children and adolescents aged 9-16 years between 1999 and 2022. The 20-m shuttle run test (20mSRT) estimated CRF. Body mass index (BMI) was calculated from measured height and body mass, with BMI z-scores (BMIz) calculated using WHO growth curves. The 20mSRT results were corrected for protocol and converted to z-scores (20mSRTz) using international sex- and age-specific norms. With additional adjustment for BMIz, temporal trends in mean 20mSRT performance (20mSRTz) were estimated using linear regression, with the distance max (Dmax) method used to locate a breakpoint and linear segments fitted to points below and above the breakpoint. Trends in distributional characteristics were assessed visually and described as the ratio of the coefficients of variation (CVs). RESULTS: After adjustment for protocol, age, sex, and BMIz, a large decline in mean 20mSRT performance (trend per decade (95% CI): -1.42 SDs (-1.45, -1.39) or -18.4% (95% CI: -18.8, -18.0)) between 1999 and 2022 was found. Dmax located a breakpoint for the two-linear-segment model in year 2010. There was a large decline in mean 20mSRT performance pre-2010 (trend per decade (95% CI): -2.31 SDs (-2.39, -2.24)), which reduced 0.06-fold to a negligible decline post-2010 (trend per decade (95% CI): -0.15 SD (-0.20, -0.10)). We also found that the trend in mean 20mSRT performance was not uniform across the population distribution. Between 1999 and 2022, there was a small trend in distributional asymmetry, with slightly smaller declines experienced by the high performers (above the 75th percentile). CONCLUSIONS: Our data suggest a large decline in the 20mSRT performance of French children and adolescents since 1999. This declining trend seems to have diminished considerably since 2010. Such declines in CRF could translate into declines in health status. Although a slowing in the declining trend in CRF in recent years is encouraging, more data are needed to confirm these findings.

Clinical and physical characteristics of thinness in adolescents: the HELENA study.

PURPOSE: Thinness in adolescence has not been studied as extensively as overweight or obesity. The aim of this study was to assess the prevalence, characteristics, and health impacts of thinness in a European adolescent population. METHODS: This study included 2711 adolescents (1479 girls, 1232 boys). Blood pressure, physical fitness, sedentary behaviors, physical activity (PA), and dietary intake were assessed. A medical questionnaire was used to report any associated diseases. A blood sample was collected in a subgroup of the population. Thinness and normal weight were identified using the IOTF scale. Thin adolescents were compared with adolescents of normal weight. RESULTS: Two hundred and fourteen adolescents (7.9%) were classified as being thin; the prevalence rates were 8.6% in girls and 7.1% in boys. Systolic blood pressure was significantly lower in adolescents with thinness. The age at the first menstrual cycle was significantly later in thin female adolescents than in those with normal weight. Upper-body muscular strength measured in performance tests and time spent in light PA were significantly lower in thin adolescents. The Diet Quality Index was not significantly lower in thin adolescents, but the percentage of adolescents who skipped breakfast was higher in adolescents with a normal weight (27.7% vs 17.1%). Serum creatinine level and HOMA-insulin resistance were lower and vitamin B12 level was higher in thin adolescents. CONCLUSIONS: Thinness affects a notable proportion of European adolescents with no physical adverse health consequences.

Validation of the IMPACT-III Questionnaire in French Children With Inflammatory Bowel Disease.

OBJECTIVES: This study assessed the reliability and validity of the IMPACT-III questionnaire, a health-related quality of life (HRQoL) instrument, in French children with inflammatory bowel disease (IBD). METHODS: Eighty-four children and adolescents (45 boys, aged 14.3 ± 2.7 years) were included in a validation study of the IMPACT-III questionnaire. Patients completed 2 questionnaires for measuring HRQoL: the IMPACT-III and the Pediatric Quality of Life Inventory 4.0 Generic Core Scale (PedsQL). Internal consistency was assessed using Cronbach α. Factor analysis was performed on data from the IMPACT-III to help construct domains. Concurrent validity was assessed by calculating Spearman correlation coefficients. RESULTS: Cronbach α for the PedsQL total score was good (0.89). The most robust factor solution was a 3-domain structure: (a) Concerns, (b) Body Image and Physical Condition, and (c) Symptoms and Socializing. All domains had good reliability (0.674-0.863). Only 2 items had to be removed. Discriminant validity was demonstrated by significant differences ( P < 0.001) in median IMPACT-III scores between inactive and active disease for the total score (83.3 vs 72.0), and for Concerns ( P < 0.002) and Symptoms and Socializing ( P < 0.001). CONCLUSIONS: These results suggest that IMPACT-III appears to be a useful instrument for measuring HRQoL in French children with IBD.

New indices in predicting cardiometabolic risk and its relation to endothelial dysfunction in adolescents: The HELENA study.

BACKGROUND AND AIMS: Blood pressure (BP) changes and insulin resistance (IR) are important cardiometabolic risk (CMR) factors; their early identification can contribute to the reduction of cardiovascular events in adulthood. This necessitates the search for more accessible and easily applied indicators for their prediction. Therefore, this study aimed to evaluate the predictive power of the indices, TyG, TG/HDL-c, height-corrected lipid accumulation product (HLAP), and visceral adiposity index (VAI), in identifying the CMR obtained by high BP and IR and to verify their relationship with biomarkers of endothelial dysfunction (ED) in European adolescents. METHODS AND RESULTS: The anthropometric data and blood biomarkers of 744 adolescents (343 boys and 401 girls) from the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS), with a mean age of 14.67 (SD 1.15) years, were assessed. The adolescents were then classified according to the presence or absence of high BP and IR. The cut-off points of the indices evaluated for the identification of CMR were determined. The relationship between CMR diagnosed using these indices and ED biomarkers was tested. The HLAP and TG/HDL-c were fair predictors of CMR obtained by IR in male adolescents. These indices showed association with hsCRP in sVCAM-1 in boys, but it lost significance after adjusting for age and body mass index. CONCLUSION: TG/HDL-c and HLAP indices showed a fair performance in predicting CMR, obtained by IR, in male adolescents. ED showed no association with the CMR identified by the indices.

Changes in physical activity patterns from adolescence to young adulthood: the BELINDA study.

Physical activity (PA) is recognized as a marker of health. The aim was to investigate PA differences from adolescence to young adulthood. European adolescents included in the HELENA study were invited to participate in a follow-up study, 10 years later. The present study included 141 adults (25.0 ± 1.4 years) for whom valid accelerometer data were available in adolescence and adulthood. Changes in PA by sex, weight and maternal education level were explored with interactions. Time spent in sedentary activity, light PA (LPA) and moderate PA (MPA) increased by 39.1, 59.6 and 6.6 min/day, respectively, whereas the time spent in vigorous PA (VPA) decreased by 11.3 min/day compared with adolescent VPA (p < 0.05). Increases in MPA were greater on weekends compared with weekdays, but we found a greater decrease in VPA on weekdays compared with weekends. Moderate-to-vigorous PA (MVPA) decreased significantly on weekdays (-9.6 min/day; 95%CI, -15.9 to -3.4), while it increased on weekends (8.4 min/day; 95%CI, 1.9 to 14.8). Significant heterogeneity was found across sexes for VPA and MVPA, with a stronger decrease in VPA in males compared with females and a significant decrease in MVPA (-12.5 min/day; 95%CI, -20.4 to -4.5) in males but not in females (1.9 min/day; 95%CI, -5.5 to 9.2). No significant heterogeneity was found to be linked to maternal education level or weight, irrespective of PA level.  Conclusion: Our data suggest that the transition from adolescence to young adulthood is a critical period for lifestyle PA habits. A decline in VPA and an increasingly sedentary time were observed. The observed changes are worrying and may increase the risk of developing adverse health consequences later in life. What is Known: • The transition from adolescence to adulthood is marked by many life changes affecting lifestyle habits. Most studies tracking physical activity from adolescence to adulthood were done using PA questionnaires, which is a subjective method. What is New: • Our study bring first data on objective changes in PA patterns between adolescence and young adulthood, taking account of BMI, sex and maternal educational level. Our results suggest that the transition from adolescence to young adulthood is a critical period for lifestyle PA habits, especially for time spent on sedentary activities.

Interplay of physical activity and genetic variants of the endothelial lipase on cardiovascular disease risk factors.

BACKGROUND: The aim of this study was to investigate the association of endothelial lipase gene (LIPG) polymorphisms with cardiovascular disease (CVD) risk factors in adolescents and their interaction with physical activity. METHODS: Six polymorphisms of LIPG were genotyped in 1057 European adolescents (12-18 years old) enrolled in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) Study. CVD risk factors related to lipid profile, blood pressure, adiposity and glucose regulation were recorded. Physical activity was objectively measured by accelerometry. RESULTS: The major C allele of rs2000813, the minor T allele of rs2276269 and the minor G allele of rs9951026 were associated with lower levels of several CVD risk factors related to lipid profile. We also found a significant association of the TTACA LIPG haplotype (rs2000812, rs2000813, rs8093249, rs2276269 and rs9951026) with higher concentrations of low-density cholesterol and apolipoprotein B. Finally, the interaction between physical activity and the polymorphisms rs2000813, rs2276269 and rs9951026 had a significant influence on several CVD risk factors. CONCLUSIONS: LIPG polymorphisms were significantly associated with CVD risk factors in European adolescents. Interestingly, alleles of these polymorphisms were associated with a better cardiovascular profile in physically active adolescents only. High physical activity may reduce the development of CVD, modulating its genetic risk. IMPACT: Using gene-phenotype and gene × environment analyses, we detected associations between the endothelial lipase gene and cardiovascular risk factors, along with interactions with physical activity. This study shows that physical activity may modulate the influence of LIPG gene on cardiovascular risk in adolescents. These results bring insights into the mechanisms by which physical activity positively influences CVD in adolescents.

Changes in (poly)phenols intake and metabolic syndrome risk over ten years from adolescence to adulthood.

BACKGROUND AND AIMS: (Poly)phenols might contribute to prevent cardiovascular disease, but limited prospective studies exist among adolescents. This study aimed to evaluate within-subject longitudinal changes in (poly)phenols intakes and food group contributors while also exploring the association with metabolic syndrome risk (MetS) during 10 years of follow up in European adolescents becoming young adults. METHODS AND RESULTS: In 164 participants (58% girls, 13-18 y at baseline) from Ghent, Zaragoza and Lille, longitudinal data (2006-2016) on (poly)phenol intake was retrieved via 2 or 3 24 h recalls. Linear and logistic longitudinal regression tested the association of (poly)phenols intake (total and classes) with Mets risk or its components (waist-height-ratio, HDL cholesterol, LDL cholesterol, triglycerides, blood pressure and insulin resistance index), adjusted for age, sex, country and other nutrient intakes. The total (poly)phenols intake was 421 ± 107 mg/day (192 mg/1000 kcal/day) at baseline, while 610 ± 101 mg/day (311 mg/1000 kcal/day) at follow-up. The three major food sources for (poly)phenols were 'chocolate', 'fruit and vegetable juices', 'cakes and biscuits' during adolescence and 'coffee', 'tea' and 'chocolate' during adulthood. Phenolic acid intake was associated with less LDL increase over time, while stilbene intake with a steeper increase in triglycerides over time. CONCLUSIONS: Differences in major (poly)phenols contributors over time were partially explained by age-specific dietary changes like increased coffee and tea during adulthood. Some significant (poly)phenols-MetS associations might argue for nutrition-based disease prevention during adolescence, especially since adolescents had low (poly)phenols intake.

Change in physical fitness due to the COVID-19 pandemic lockdown in French adolescents: a comparison between two independent large samples from Diagnoform battery.

Numerous studies reported a significant decline in physical activity level in adolescents as a result of the COVID-19 lockdown. Physical fitness is recognized as a powerful marker of health in youth. The aim of this study was to evaluate the impact of the COVID-19 pandemic lockdown on health-related physical fitness in French adolescents. Two cross-sectional studies were performed comparing two different groups of French adolescents, before (sample 1) and after the first lockdown (sample 2). A total of 1231 adolescents (aged to 16.5 ± 1.5 years) participated in the two cross-sectional studies. Complete data for physical fitness and anthropometrics data were obtained. Adolescents from sample 2 showed lower physical fitness levels compared to adolescents from sample 1. Regarding physical fitness for boys and girls, physical fitness levels were significantly lower in both sex between adolescents from the sample 1 and adolescents from the sample 2, except for cardiorespiratory fitness and flexibility for boys and girls, respectively. The physical fitness global score was also significantly lower between adolescents from the sample 1 and 2 for boys (-9.8%, p < 0.01) and girls (-16.2%; p < 0.01), respectively. Overall, the higher difference was found for performance in the speed body displacement test (-30%). A difference of 12.8% and 25% was observed for boys and girls, respectively.   Conclusion: COVID-19 pandemic lockdown had a negative impact on physical fitness in French youth. This study highlights the need to develop, in a near future, prevention programmes in order to improve the physical fitness in youth. What is Known: • COVID-19 pandemic deeply impacted lifestyle habits. A worrying decrease of physical activity, associated to a dramatic increase of time spent in sedentary behaviors was found in many coutries. What is New: • Our study bring first data on the health-related physical fitness consequences due to lockdown in French adolescents. Our study demonstrate the negative impact of COVID-19 pandemic lockdown on health-related physical fitness in French adolescents.

Cardiometabolic Risk is Positively Associated with Underreporting and Inversely Associated with Overreporting of Energy Intake Among European Adolescents: The Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) Study.

BACKGROUND: Dietary misreporting is the main limitation of dietary assessments and has been associated with BMI during youth. However there are no prior studies assessing misreporting and cardiometabolic risks (CMRs) in adolescence. OBJECTIVES: To examine the associations between dietary misreporting and CMR factors in adolescents and to assess the potential bias in the association between CMR and energy intake (EI) driven by dietary misreporting. METHODS: Two 24-hour dietary recalls were obtained from 1512 European adolescents (54.8% girls) aged 12.5-17.5 years. Physical activity was measured by accelerometry. Cut-offs suggested by Huang were applied to identify misreporters. Height, waist circumference (WC), the sum of 4 skinfold thicknesses, diastolic blood pressure (DBP), systolic blood pressure (SBP), and cardiorespiratory fitness (CRF) measurements were taken and serum triglycerides and total-/high-density lipoprotein cholesterol ratio were analyzed. A sex- and age-specific clustered CMR score (n = 364) was computed. Associations were investigated by multilevel regression analyses adjusting for age, sex, center, socioeconomic status, and physical activity. RESULTS: Underreporting (24.8% adolescents) was significantly (P < 0.05) associated with a higher WC, waist-to-height ratio (WHeR), and sum of skinfold thickness, whereas overreporting (23.4% adolescents) was significantly associated with a lower WC, WHeR, sum of skinfold thickness, and SBP. Associations between CMR factors and EI were significantly affected by misreporting, considering various approaches. Significant, positive associations became inverse after adjusting for misreporting for WC and WHeR. The opposite was true for the sum of skinfold thickness, SBP, and CMR score. The associations between EI and DBP and CRF did not remain significant after adjusting for misreporting. CONCLUSIONS: CMR factors differed among misreporting groups, and both abdominal and total fat mass indicators were more strongly associated with all forms of misreporting than was BMI. Moreover, misreporting seems to bias EI and CMR associations in adolescents. Therefore, energy misreporting should be taken into account when examining diet-CMR associations.

Daily physical activity patterns in children and adolescents with inflammatory bowel disease.

BACKGROUND: The aim of this study was to assess PA patterns among children and adolescents with inflammatory bowel disease (IBD). METHODS: Sixty participants with IBD (42 Crohn's disease [CD], 10 ulcerative colitis [UC], and 8 IBD-unclassified [IBD-U], 30 male patients) in remission (n = 45) or with mild disease (n = 15) were compared with 60 healthy age- and sex-matched controls. Each participant wore a triaxial accelerometer during 4 consecutive days for objective daily PA quantification. RESULTS: Overall, there was no significant difference in daily PA patterns between patients with IBD and healthy controls, with 31.7% of patients with IBD and 38.3% of healthy controls fulfilling the recommendation of 60 min of moderate-to-vigorous physical activity (MVPA) daily (NS). Male patients with IBD spent significantly less time in MVPA compared with matched healthy controls (mean difference, 16.2 min day-1; p < 0.05). No difference was observed for female patients with IBD. No difference in sedentary pattern between male patients with IBD and controls was found. CONCLUSIONS: Children and adolescents with inactive or mildly active IBD have similar PA patterns compared with healthy controls, except for male patients who have reduced moderate-to-vigorous PA. By far, most patients with IBD do not fulfill the MVPA recommendations for health benefits. IMPACT: There is few data on PA patterns in pediatric patients with IBD. Methodological issues to assess PA limit the strengths of these studies. Pediatric IBD patients with inactive or mildly active IBD have similar physical activity patterns compared with healthy controls, except for male patients who have reduced moderate-to-vigorous PA. Most patients with IBD do not fulfill the MVPA recommendations for health benefits.

School time is associated with cardiorespiratory fitness in adolescents: The HELENA study.

We assessed the association between school time and physical fitness in adolescents. The study included 2,024 adolescents, aged 12.5-17.5 years, who participated in the Healthy Lifestyle in Europe by Nutrition in Adolescence study. Health-related physical fitness components were assessed using the physical fitness tests battery. Cardiovascular risk was categorized using the sex-specific cut-offs for a healthy cardiorespiratory fitness level in adolescents proposed by FitnessGram®. School time was classified as short or long. Multivariate analysis accounted for confounding factors such age, sex, body mass index, time spent in moderate to vigorous physical activity, pubertal status, and parents' educational level. Cardiorespiratory fitness was higher in adolescents with a long school time than in those with a short school time (42.0 ± 7.6 vs 40.7 ± 7.2 mL.kg-1.min-1, respectively; p < 0.05). The percentage of adolescents at cardiovascular risk in adulthood was higher in the short than in the long time group (45.2% vs 31.7%, respectively) (p < 0.05). These findings suggest that a long school day is associated with higher cardiorespiratory fitness in adolescents and that school time should be considered in interventions and health promotion strategies.

Association between CNTF Polymorphisms and Adiposity Markers in European Adolescents.

OBJECTIVE: To examine the association between polymorphisms of the ciliary neurotrophic factor gene (CNTF) and total and central adiposity markers in adolescents. STUDY DESIGN: This cross-sectional study involved 1057 European adolescents aged 12-18 years enrolled in the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study. Five polymorphisms of CNTF were genotyped, and the weight, height, waist and hip circumference, and triceps and subscapular skinfold thickness of the subjects were measured and recorded. RESULTS: The T allele of rs2509914, the C allele of rs2515363, and the G allele of rs2515362 were significantly associated (after Bonferroni correction) with higher values for several adiposity markers under different inheritance models. The CNTF CCGGA haplotype (rs2509914, rs17489568, rs2515363 rs1800169, and rs2515362) was also significantly associated with lower body mass index, waist circumference, waist/height ratio, and waist/hip ratio values compared with the TCCGG haplotype under several inheritance models. CONCLUSIONS: Three polymorphisms-rs2509914, rs2515363, and rs2515362-and the CCGGA haplotype of CNTF were significantly associated with adiposity in European adolescents. These results suggest the potential role of CTNF in the development of obesity-related phenotypes.

Severe preschool asthmatics have altered cytokine and anti-viral responses during exacerbation.

BACKGROUND: Preschool asthma/recurrent wheeze is a heterogeneous condition. Different clinical phenotypes have been described, including episodic viral wheeze (EVW), severe intermittent wheeze (SIW), and multiple-trigger wheeze (MTW). OBJECTIVE: To compare clinical, viral, and inflammatory/immune profiling at exacerbation between MTW, SIW, and EVW phenotypes. METHODS: Multicenter, prospective, observational cohort (VIRASTHMA-2). Children (1-5 years) with preschool asthma were enrolled during hospitalization for a severe exacerbation. History and anamnestic data, plasma, and nasal samples were collected at exacerbation (T1) and at steady state, 8 weeks later (T2), and sputum samples were collected at T1. RESULTS: A total of 147 children were enrolled, 37 (25%) had SIW, 18 (12.2%) EVW, and 92 (63%) MTW. They were atopic (47%), exposed to mold (22%) and cigarette smoke (50%), and prone to exacerbations (≥2 in the previous year in 70%). At exacerbation, at least one virus was isolated in 94% and rhinovirus in 75%, with no difference between phenotypes. Children with MTW and SIW phenotypes displayed lower plasma concentrations of IFN-γ (P = .002), IL-5 (P = .020), TNF-α (P = .038), IL-10 (P = .002), IFN-ß (P = .036), and CXCL10 (P = .006) and lower levels of IFN-γ (P = .047) in sputum at exacerbation than children with EVW. At T2, they also displayed lower plasma levels of IFN-γ (P = .045) and CXCL10 (P = .013). CONCLUSION: Among preschool asthmatic children, MTW and SIW, prone to exacerbations, display lower systemic levels of Th1, Th2 cytokines, pro- and anti-inflammatory cytokines, and antiviral responses during severe virus-induced exacerbation.

Association between lipoprotein lipase gene polymorphisms and cardiovascular disease risk factors in European adolescents: The Healthy Lifestyle in Europe by Nutrition in Adolescence study.

OBJECTIVES: To examine the association of lipoprotein lipase (LPL) polymorphisms with cardiovascular disease (CVD) risk factors in European adolescents, along with the influence of physical activity on these associations. METHODS: A total of 13 LPL polymorphisms were genotyped in 1.057 European adolescents (12-18 years old) from the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study. Serum lipids, glucose, insulin, and leptin (LEP) levels were measured and a CVD risk score was computed. We also measured body weight and height, waist and hip circumferences, and triceps and subscapular skinfold thickness. Physical activity was objectively measured by accelerometry for 7 days. RESULTS: The rs1534649, rs258, rs320, and rs328 polymorphisms were associated with several CVD risk factors (ie, body mass index, triglycerides [TG], LEP, and cholesterol/high-density lipoprotein [HDL], low-density lipoprotein [LDL]/HDL, TG/HDL ratios). TG and TG/HDL were associated with haplotype blocks 3 (rs282, rs285 polymorphisms) and 4 (rs3126, rs320, rs328, rs10099160 polymorphisms), being the latter also associated with the CVD risk score. Physical activity modulated the association of adiposity with rs1534649 and rs258 polymorphisms. CONCLUSIONS: Polymorphisms rs1534649, rs258, rs320 and rs328, and two haplotypes of LPL were significantly associated with CVD risk factors in European adolescents. Higher levels of moderate to vigorous physical activity may attenuate the effects of rs1534649 and rs258 polymorphisms on adiposity.

Dietary Patterns and Their Relationship With the Perceptions of Healthy Eating in European Adolescents: The HELENA Study.

Objective: The aim of this study was to identify dietary patterns (DPs) in European adolescents and to examine the association between perceptions of healthy eating and the obtained DPs.Method: A multinational cross-sectional study was carried out in adolescents aged 12.5 to 17.5 years and 2,027 (44.9% males) were considered for analysis. A self-reported questionnaire with information on food choices and preferences, including perceptions of healthy eating, and two 24-hour dietary recalls were used. Principal component analysis was used to obtain sex-specific DPs, and linear analyses of covariance were used to compare DPs according to perceptions of healthy eating.Results: Three and four DPs for boys and girls were obtained. In boys and girls, there were significant associations between some perceptions about healthy food and the Breakfast-DP (p < 0.05). In boys, Breakfast-DP and Healthy Beverage-DP were associated with the perception of the own diet as healthy (p < 0.05). Healthy Beverage-DP was associated with those disliking fruits and vegetables (p < 0.05). Girls considering the own diet as healthy were associated with Mediterranean-DP, Breakfast-DP, and Unhealthy Beverage and Meat-DP (p < 0.05). The perception of snacking as a necessary part of a healthy diet was associated with Breakfast-DP in both genders (p < 0.05).Conclusions: In European adolescents, perceptions of healthy eating were mainly associated with a DP characterized by foods consumed at breakfast. Future studies should further explore these findings in order to implement health promotion programs to improve healthy eating habits in adolescents.

Comparison and validation of accelerometer wear time and non-wear time algorithms for assessing physical activity levels in children and adolescents.

BACKGROUND: Accelerometers are widely used to measure sedentary time and daily physical activity (PA). However, data collection and processing criteria, such as non-wear time rules might affect the assessment of total PA and sedentary time and the associations with health variables. The study aimed to investigate whether the choice of different non-wear time definitions would affect the outcomes of PA levels in youth. METHODS: Seventy-seven healthy youngsters (44 boys), aged 10-17 years, wore an accelerometer and kept a non-wear log diary during 4 consecutives days. We compared 7 published algorithms (10, 15, 20, 30, 60 min of continuous zeros, Choi, and Troiano algorithms). Agreements of each algorithm with the log diary method were assessed using Bland-Altmans plots and by calculating the concordance correlation coefficient for repeated measures. RESULTS: Variations in time spent in sedentary and moderate to vigorous PA (MVPA) were 30 and 3.7%. Compared with the log diary method, greater discrepancies were found for the algorithm 10 min (p < 0.001). For the time assessed in sedentary, the agreement with diary was excellent for the 4 algorithms (Choi, r = 0.79; Troiano, r = 0.81; 30 min, r = 0.79; 60 min, r = 0.81). Concordance for each method was excellent for the assessment of time spent in MVPA (> 0.86). The agreement for the wear time assessment was excellent for 5 algorithms (Choi r = 0.79; Troiano r = 0.79; 20 min r = 0.77; 30 min r = 0.80; 60 min r = 0.80). CONCLUSIONS: The choice of non-wear time rules may considerably affect the sedentary time assessment in youth. Using of appropriate data reduction decision in youth is needed to limit differences in associations between health outcomes and sedentary behaviors and may improve comparability for future studies. Based on our results, we recommend the use of the algorithm of 30 min of continuous zeros for defining non-wear time to improve the accuracy in assessing PA levels in youth. TRIAL REGISTRATION: NCT02844101 (retrospectively registered at July 13th 2016).

Mediation of psychosocial determinants in the relation between socio-economic status and adolescents' diet quality.

PURPOSE: To examine the underlying reasons for the positive relation between socio-economic status (SES) and the diet quality of adolescents. METHODS: In 2081 adolescents (12.5-17.5 years) of the European HELENA study, a continuous variable on diet quality via 2-day 24-h recalls was available. SES was reflected by parental education, parental occupation and family affluence. Mediation by several psychosocial determinants was tested: self-efficacy, availability at school and home, social support, barriers, benefits, awareness and some self-reported influencers (parents, school, taste, health, friends, food readily available, easy preparation, hunger, price and habits). Multiple mediation analyses were adjusted for age, sex and country. RESULTS: The availability of soft drinks and fruit at home, social support, parental influence, barriers, price influence, taste influence, health influence and food being readily available were significant mediators. The multiple mediation indirect effect accounted for 23-64% of the total effect. Both occupation and education and both maternal and paternal factors could be explained by the mediation. The unavailability of soft drinks was the strongest mediator (17-44% of the total effect). CONCLUSION: Up to 64% of the positive relation between SES and the diet quality in adolescence could be explained by several healthy eating determinants. Focusing on these factors in low-SES populations can minimize social inequalities in diet and health by improving the diet of these specific adolescents.

Adolescents' diet quality in relation to their relatives' and peers' diet engagement and encouragement: the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study.

OBJECTIVE: To examine the associations between adolescents' diet quality and their perceived relatives' and peers' diet engagement and encouragement. DESIGN: Cross-sectional study performed in European countries. Diet quality was scored using the Diet Quality Index for Adolescents (DQI-A) based on four components: quality, diversity, balance and meal frequency. Perceived diet quality engagement and perceived encouragement of the relatives/peers were assessed using the questions 'How healthy is each of the following persons' diet?' and 'How often does each of the following persons encourage you to eat a healthy diet?' SETTING: Vienna, Ghent, Lille, Athens, Heraklion, Pecs, Rome, Dortmund, Zaragoza and Stockholm. SUBJECTS: Healthy adolescents (n 2943). RESULTS: The perceived engagement level of the mother, father and sister was each positively associated with the DQI-A (P<0·05). A positive association was found for the perceived engagement level of siblings, father and mother with all specific components (P<0·05). DQI-A was negatively associated with the perceived encouragement level from a best friend and positively associated with the encouragement level of the mother and father (P<0·05). Diversity, balance and quality components were positively associated with the perceived encouragement level from the mother and father (P<0·05), whereas the best friend's perceived encouragement was negatively associated with the meal frequency component (P<0·01). CONCLUSIONS: These findings highlight the role of social engagement and encouragement of relatives and peers in adolescents' diet quality. Intervention or promotion programmes aimed at enhancing diet quality in adolescents should target both family and peers.

Physical activity awareness of European adolescents: The HELENA study.

The aim of this study was to assess physical activity (PA) awareness of adolescents and to identify anthropometric and psychosocial factors that can lead to under or overestimation of PA. This study included 2044 adolescents. Participants wore a uniaxial accelerometer for 7 days to measure PA and completed a self-rated questionnaire about PA. Adolescents were classified into four PA awareness subgroups (realistically active, overestimators, underestimators and realistically inactive) according to the self-rated and objective assessment of PA. Characteristics and psychosocial factors of the self-rated physically active groups were compared using bivariate and multivariate mixed logistic regression models. Forty-five percent of adolescents reported their PA levels correctly (34.8% realistically active and 10.1% realistically inactive). Among the 59.4% who were objectively inactive, 82.9% tended to overestimate their PA level. Adolescents who overestimated their PA level were older (P < .05), had more support from mother and a best friend (P < .05) and had higher cardiorespiratory fitness (P < .001) compared with those who were realistically active. A significant number of adolescents believe that they are physically active when they are not. Improving awareness, especially in the high-risk groups identified here, might help to bring about behavioural changes in physically inactive adolescents.

Awareness of wearing an accelerometer does not affect physical activity in youth.

BACKGROUND: This study aimed to investigate whether awareness of being monitored by an accelerometer has an effect on physical activity in young people. METHODS: Eighty healthy participants aged 10-18 years were randomized between blinded and nonblinded groups. The blinded participants were informed that we were testing the reliability of a new device for body posture assessment and these participants did not receive any information about physical activity. In contrast, the nonblinded participants were informed that the device was an accelerometer that assessed physical activity levels and patterns. The participants were instructed to wear the accelerometer for 4 consecutive days (2 school days and 2 school-free days). RESULTS: Missing data led to the exclusion of 2 participants assigned to the blinded group. When data from the blinded group were compared with these from the nonblinded group, no differences were found in the duration of any of the following items: (i) wearing the accelerometer, (ii) total physical activity, (iii) sedentary activity, and (iv) moderate-to-vigorous activity. CONCLUSIONS: Our study shows that the awareness of wearing an accelerometer has no influence on physical activity patterns in young people. This study improves the understanding of physical activity assessment and underlines the objectivity of this method. TRIAL REGISTRATION: NCT02844101 (retrospectively registered at July 13th 2016).