The CODATwins Project: The Current Status and Recent Findings of COllaborative Project of Development of Anthropometrical Measures in Twins.

The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m2) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural-geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status.

Skeletal maturation, fundamental motor skills, and motor performance in preschool children.

Relationships among skeletal age (SA), body size and fundamental motor skills (FMS) and motor performance were considered in 155 boys and 159 girls 3-6 years of age. Stature and body mass were measured. SA of the hand-wrist was assessed with the Tanner-Whitehouse II 20 bone method. The Test of Gross Motor Development, 2nd edition (TGMD-2), and the Preschool Test Battery were used, respectively, to assess FMS and motor performance. Based on hierarchical regression analyses, the standardized residuals of SA on chronological age (SAsr) explained a maximum of 6.1% of the variance in FMS and motor performance in boys (ΔR2 3 , range 0.0%-6.1%) and a maximum of 20.4% of the variance in girls (ΔR2 3 , range 0.0%-20.4%) over that explained by body size and interactions of SAsr with body size (step 3). The interactions of the SAsr and stature and body mass (step 2) explained a maximum of 28.3% of the variance in boys (ΔR2 2 , range 0.5%-28.3%) and 16.7% of the variance in girls (ΔR2 2 , range 0.7%-16.7%) over that explained by body size alone. With the exception of balance, relationships among SAsr and FMS or motor performance differed between boys and girls. Overall, SA per se or interacting with body size had a relatively small influence in FMS and motor performance in children 3-6 years of age.

Body mass index and motor coordination: Non-linear relationships in children 6-10 years.

BACKGROUND: Given the concern for health-related consequences of an elevated body mass index (BMI; obesity), the potential consequences of a low BMI in children are often overlooked. The purpose was to evaluate the relationship between the BMI across its entire spectrum and motor coordination (MC) in children 6-10 years. METHODS: Height, weight, and MC (Körperkoordinationstest für Kinder, KTK test battery) were measured in 1,912 boys and 1,826 girls of 6-10 years of age. BMI (kg/m2 ) was calculated. KTK scores for each of the four tests were also converted to a motor quotient (MQ). One-way ANOVA was used to test differences in the BMI, individual test items, and MQ among boys and girls within age groups. Sex-specific quadratic regressions of individual KTK items and the MQ on the BMI were calculated. Girls and boys were also classified into four weight status groups using International Obesity Task Force criteria: thin, normal, overweight, and obese. Differences in specific test items and MQ between weight status groups were evaluated by age group in each sex. RESULTS: Thirty-one percent of the sample was overweight or obese, whereas 5% was thin. On average, normal weight children had the highest MQ in both sexes across the age range with few exceptions. Overweight/obese children had a lower MQ than normal weight and thin children. The quadratic regression lines generally presented an inverted parabolic relationship between the BMI and MC and suggested a decrease in MC with an increase in the BMI. CONCLUSION: In general, BMI shows a curvilinear, inverted parabolic relationship with MC in children 6-10 years.

Modeling children's development in gross motor coordination reveals key modifiable determinants. An allometric approach.

Children change their body size, shape, and gross motor coordination (GMC) as they grow. Further, GMC is expected to link to changes in children's body size, physical activity (PA), and physical fitness (PF). The objective was to model GMC changes in children followed longitudinally and to investigate associations between these changes and PA and PF levels. A total of 245 children (122 girls) were observed at 6 years of age and followed annually until 9 years. A sequence of allometric models was fitted, that is, 1. body mass, stature, and PA; 2. addition of four PF tests; 3. addition of four more PF tests. In Model 1, changes in GMC are nonlinear, and body mass (-0.60 ± 0.07, P < .001) and stature (2.91 ± 0.35, P < .001) parameter estimates were significant suggesting children with a more linear body size/shape showed higher GMC performances. Girls tend to outperform boys across time, and PA was not associated with GMC changes. Model 2 fitted the data better, and the PF tests (handgrip, standing long jump, 50-yard dash, and shuttle run) were significantly linked to GMC change. In Model 3, adding the remaining PF tests did not change the order of any factors importance. The greatest GMC changes were achieved by children whose body size/shape has an ectomorphic dominance across the years. Considering that leaner and physically fitter children tended to be more coordinated, physical education should also focus on PF development in components related to muscular strength, speed, agility, and aerobic capacity, along with nutritional education to reduce fat mass.

The ability of topical and systemic statins to increase osteogenesis around dental implants: a systematic review of histomorphometric outcomes in animal studies.

The purpose of this systematic review was to evaluate the quantitative histomorphometric outcomes of animal studies investigating statins as a pro-osteogenic agent to enhance the osseointegration of dental implants. Some animal studies have suggested a beneficial action of statins on bone tissue. Electronic and manual literature searches, without date or language restriction, ​​were performed by two independent review authors up to February 2017. Eligibility criteria included animal trials quantitatively analysing the pro-osteogenic effect of statins on dental implants. The quality of the included studies was assessed using the ARRIVE guidelines. The search and selection process yielded 12 studies, published between 2004 and 2015. The experimental animals models used were rats and dogs. The statins used in the studies were simvastatin and fluvastatin, which were administered locally or systemically, or applied to the implant surface. All of the selected studies showed a statistically significant positive effect of statins on bone formation around implants. The mean quality assessment score (ARRIVE) of the studies was 11.5±2.27 out of a possible total of 25 points. The histomorphometric data from available preclinical studies suggest a positive effect of statins on increasing osteogenesis around dental implants.

Resemblance in physical activity levels: The Portuguese sibling study on growth, fitness, lifestyle, and health.

OBJECTIVES: To investigate the relationships of biological, behavioral, familial, and environmental characteristics with siblings´ physical activity (PA) levels as well as the intrapair resemblance in PA. METHODS: The sample comprises 834 (390 females) biological siblings [brother-brother (BB), sister-sister (SS), brother-sister (BS)] aged 9 to 20 years. Total PA index (TPAI) was estimated by questionnaire. Information on potential behavioral, familial, and environmental correlates was obtained by self-report; body mass index (BMI), biological maturation, and physical fitness were measured. Multilevel models were used to analyze siblings´ clustered data, and sibling resemblance was estimated with the intraclass correlation (ρ). RESULTS: On average, younger sibs, those more physically fit, and those with more parental support had greater TPAI. Further, BB pairs had higher TPAI levels than SS or BS pairs, but also had greater within-pair variance. When adjusted for all covariates, SS pairs demonstrated greater resemblance in TPAI (ρ = 0.53, 95%CI = 0.38-0.68) than BS (ρ = 0.26, 95%CI = 0.14-0.43) or BB pairs (ρ = 0.18, 95%CI = 0.06-0.44). CONCLUSIONS: Age, physical fitness, and parental support were the best predictors of TPAI levels. A moderate level of resemblance in TPAI was observed in SS pairs, while lower resemblance was found for BS and BB pairs. These findings may be due to differences in the roles of shared genetic factors, familial, and environmental characteristics across different sibling types.

Three-dimensional changes to the upper airway after maxillomandibular advancement with counterclockwise rotation: a systematic review and meta-analysis.

The aim of this study was to evaluate the effect of counterclockwise (CCW) rotation and maxillomandibular advancement (MMA) on the upper airway space using three-dimensional images. An electronic search was performed in the PubMed, Cochrane Library, Scopus, Virtual Health Library, Web of Science, and OpenGrey databases (end date July 2016); a hand-search of primary study reference lists was also conducted. The inclusion criteria encompassed computed tomography evaluations of the upper airway spaces of adult patients undergoing orthognathic surgery with CCW rotation and MMA. The articles were evaluated for risk of bias with a tool for before-and-after studies. A meta-analysis was performed with the mean differences using a random-effects model. Heterogeneity was assessed with the Q-test and the I2 index. The meta-analysis revealed significant (P<0.001) increases in both the total airway volume (effect size of 6832mm3 and confidence interval of 5554-8109mm3) and the minimum axial area (effect size of 92mm2 and confidence interval of 70-113mm2). The heterogeneity was low in both comparisons (I2=38% and 7%, respectively). The technique of mandibular advancement with CCW rotation produced significant increases in the volumes and areas of the upper airway spaces.

Correlates of children's compliance with moderate-to-vigorous physical activity recommendations: a multilevel analysis.

This study aimed to investigate the association between individual and school characteristics associated with the number of school days children comply with moderate-to-vigorous physical activity (MVPA) recommendations. Sample comprises 612 Portuguese children, aged 9-11 years, from 23 schools. Time spent in MVPA was measured by accelerometry, while individual-level correlates were obtained by anthropometry and questionnaires. School-level variables were collected by questionnaire, and accelerometer wear time and season were also considered. Maximum likelihood estimates of model parameters were obtained via a multilevel analysis with children as level-1, and school as level-2. Children who spent more time in sedentary activities and girls were less likely to comply with MVPA/daily. More mature children and those who use active transportation to school were more likely to attain the PA recommendation. Furthermore, greater accelerometer wear time and spring season increased the chance to achieve the recommended MVPA. In terms of school-level correlates, a greater number of available facilities was negatively associated with children MVPA compliance. Given the set of variables, our results showed that individual characteristics seem to be more relevant for children's compliance rates with PA/day than school context variables, which should be taken into account in the implementation of school policies and practices.

Body mass index, cardiorespiratory fitness and cardiometabolic risk factors in youth from Portugal and Mozambique.

OBJECTIVES: The objectives of this study are to examine differences in cardiometabolic risk indicators, as well as their prevalences, in Portuguese and Mozambican youth, and to investigate the associations between weight status and cardiorespiratory fitness levels with cardiometabolic risk. METHODS: The sample comprises 721 adolescents (323 Mozambican and 398 Portuguese), aged 10-15 years. Anthropometry (height, sitting height, weight and waist circumference), blood pressure, serum-fasting triglycerides, high-density lipoprotein cholesterol and glucose, and cardiorespiratory fitness were measured. Maturity offset was estimated and a cardiometabolic risk score adjusted for sex, age and biological maturity was computed. Adolescents were classified as normal weight and overweight/obese as well as fit or unfit (cardiorespiratory fitness). RESULTS: Portuguese youth have better cardiometabolic and cardiorespiratory fitness profiles. About 32% and 30% of Portuguese boys and girls, respectively, are overweight/obese; in Mozambicans, these prevalences are 7.5% for boys and 21% for girls; in addition, 81.6% of Portuguese boys and 77.7% of Portuguese girls were classified as cardiorespiratory fit, against 54% and 44.4% of Mozambican boys and girls, respectively. No statistically significant differences (P>0.05) were found between Mozambicans and Portuguese for the cluster of three or more cardiometabolic risk indicators. A positive relationship (P<0.001) was found between weight status and cardiometabolic risk in adolescents from both countries; however, a negative association (P<0.001) between cardiorespiratory fitness and cardiometabolic risk was only found among Portuguese youth. CONCLUSIONS: Portuguese and Mozambican youth differ in their cardiometabolic risk profiles, body weight and cardiorespiratory fitness, favoring Portuguese. Overweight/obesity and low cardiorespiratory fitness levels are related to a worse cardiometabolic risk profile, being relevant to design public health intervention strategies to reduce excess weight and increase cardiorespiratory fitness.

Modeling the dynamics of BMI changes during adolescence. The Oporto Growth, Health and Performance Study.

OBJECTIVES: The aims of this study were twofold: (i) to model changes in body mass index (BMI) of 10-18-year-old adolescents, and (ii) to investigate the effects of total physical activity (TPA), physical fitness (PF), sleep duration and fruit/vegetable consumption in BMI trajectories across time. METHODS: Data were obtained from the Oporto Growth, Health and Performance Study and comprised 6894 adolescents (3418 girls) divided into four age cohorts (10, 12, 14 and 16 years) measured annually for 3 years. BMI was computed using the standard formula (kg m(-2)); TPA was estimated with the Baecke questionnaire; PF measures included 1-mile run/walk, 50 yard dash (50YD), standing long jump (SLJ), handgrip strength (HGr) and agility shuttle run. Longitudinal changes in BMI were analyzed using the multilevel modeling approach. RESULTS: The average BMI at age of peak of height velocity was 20.7±0.07 kg m(-2) for girls (P<0.001) and 20.58±0.06 kg m(-2) for boys (P<0.001). The annual increment in BMI was 1.36±0.04 kg m(-2), P<0.001 and 1.23±0.03 kg m(-2), P<0.001 for girls and boys, respectively. PF were related to BMI trajectories in both sexes (Girls: ß1mile=0.12±0.02, P<0.001; ßSLJ=-0.01±0.00, P<0.001; ß50YD=0.28±0.05, P<0.001; ßHGr=-8.91±0.54, P<0.001; Boys: ß1mile=0.18±0.02, P<0.001; ßSLJ=-0.01±0.00, P<0.001; ß50YD=0.26±0.04, P<0.001; and ßHGr=-8.15±0.45, P<0.001). TPA only showed significant, but positive, association with girls' BMI trajectories (ß=0.10±0.03, P=0.001). After adjusting for the covariates, sleep duration and fruit/vegetable intake did not show any significant association with BMI trajectories either sex. CONCLUSIONS: BMI increased linearly with age in both gender. PF levels are negatively associated with BMI across time in both boys and girls. Therefore, promotion of PF in the adolescent years seems to be effective in the early prevention of obesity.

Confirmatory factorial analysis of the children´s attraction to physical activity scale (capa).

AIM: Attraction to physical activity (PA) is an important contributor to children´s intrinsic motivation to engage in games, and sports. Previous studies have supported the utility of the children´s attraction to PA scale (CAPA) (Brustad, 1996) but the validity of this measure for use in Portugal has not been established. The purpose of this study was to cross-validate the shorter version of the CAPA scale in the Portuguese cultural context. METHODS: A sample of 342 children (8--10 years of age) was used. Confirmatory factor analyses using EQS software ( version 6.1) tested t hree competing measurement models: a single--factor model, a five factor model, and a second order factor model. RESULTS: The single--factor model and the second order model showed a poor fit to the data. It was found that a five-factor model similar to the original one revealed good fit to the data (S--B χ 2 (67) =94.27,p=0.02; NNFI=0.93; CFI=0.95; RMSEA=0.04; 90%CI=0.02;0.05). CONCLUSIONS: The results indicated that the CAPA scale is valid and appropriate for use in the Portuguese cultural context. The availability of a valid scale to evaluate attraction to PA at schools should provide improved opportunities for better assessment and understanding of children´s involvement in PA.

Genotype by energy expenditure interaction and body composition traits: The Portuguese Healthy Family Study.

BACKGROUND AND AIMS: Energy expenditure has been negatively correlated with fat accumulation. However, this association is highly variable. In the present study we applied a genotype by environment interaction method to examine the presence of Genotype x by Total Daily Energy Expenditure and Genotype x by Daily Energy Expenditure interactions in the expression of different body composition traits. METHODS AND RESULTS: A total of 958 subjects from 294 families of The Portuguese Healthy Family Study were included in the analysis. TDEE and DEE were assessed using a physical activity recall. Body fat percentages were measured with a bioelectrical impedance scale. GxTDEE and GxDEE examinations were performed using SOLAR 4.0 software. All BC traits were significantly heritable, with heritabilities ranging from 21% to 34%. The GxTDEE and GxDEE interaction models fitted the data better than the polygenic model for all traits. For all traits, a significant GxTDEE and GxDEE interaction was due to variance heterogeneity among distinct levels of TDEE and DEE. For WC, GxTDEE was also significant due to the genetic correlation function. CONCLUSIONS: TDEE and DEE are environmental constraints associated with the expression of individuals' BC genotypes, leading to variability in the phenotypic expression of BC traits.

Association between birth weight and neuromotor performance: a twin study.

Studies have shown important associations between low birth weight (BW), a variety of morbidities, and reduced motor performance. Using a twin sample, this study aimed to verify (a) the magnitude of the association between BW and neuromotor performance (NMP); (b) if the NMP of twins is within the normal range; and (c) if monozygotic (MZ) and dizygotic (DZ) twins' intra-pair similarities in NMP are of equal magnitude. We sampled 191 twins (78 MZ; 113 DZ distinguished through their DNA), aged 8.9 ± 3.1 years with an average BW of 2246.3 ± 485.4 g; gestational characteristics and sports practices were also assessed. The Zurich Neuromotor test battery, comprising five main tasks, was used; Twins NMP assessments were highly reliable (intra-rater reliability: 0.76-0.99). BW accounted for up to 11% of the total variance of NMP across the zygosity groups. Between 32.7% and 76.9% of children were below the 10th percentile for tasks requiring timing of performance (purely motor task, adaptive fine motor task, dynamic, and static balance), while less than 6.4% of children were below the 10th percentile for associated movements. MZ twins NMP intraclass correlations showed greater similarity than DZ twins in three of the five tasks, suggesting the importance of genetic factors in NMP.

Familial aggregation of metabolic syndrome indicators in Portuguese families.

BACKGROUND AND AIMS: Family studies are well suited to investigate the genetic architecture underlying the metabolic syndrome (MetS). The purposes of this paper were (i) to estimate heritabilities for each of the MetS indicators, and (ii) to test the significance of familial intratrait and cross-trait correlations in MetS markers. METHODS AND RESULTS: This study included 1,363 individuals from 515 Portuguese families in which five MetS components, including waist circumference (WC), blood pressure (BP), HDL-cholesterol, triglycerides (TG), and glucose (GLU), were measured. Intratrait and cross-trait familial correlations of these five components were estimated using Generalized Estimating Equations. Each MetS component was significantly heritable (h (2) ranged from 0.12 to 0.60) and exhibited strong familial resemblance with correlations between biological relatives of similar magnitude to those observed between spouses. With respect to cross-trait correlations, familial resemblance was very weak except for the HDL-TG pair. CONCLUSIONS: The present findings confirm the idea of familial aggregation in MetS traits. Spousal correlations were, in general, of the same magnitude as the biological relatives' correlations suggesting that most of the phenotypic variance in MetS traits could be explained by shared environment.

Genetic and environmental influences on blood pressure and physical activity: a study of nuclear families from Muzambinho, Brazil

Blood pressure (BP) and physical activity (PA) levels are inversely associated. Since genetic factors account for the observed variation in each of these traits, it is possible that part of their association may be related to common genetic and/or environmental influences. Thus, this study was designed to estimate the genetic and environmental correlations of BP and PA phenotypes in nuclear families from Muzambinho, Brazil. Families including 236 offspring (6 to 24 years) and their 82 fathers and 122 mothers (24 to 65 years) were evaluated. BP was measured, and total PA (TPA) was assessed by an interview (commuting, occupational, leisure time, and school time PA). Quantitative genetic modeling was used to estimate maximal heritability (h²), and genetic and environmental correlations. Heritability was significant for all phenotypes (systolic BP: h² = 0.37 ± 0.10, P < 0.05; diastolic BP: h² = 0.39 ± 0.09, P < 0.05; TPA: h² = 0.24 ± 0.09, P < 0.05). Significant genetic (r g) and environmental (r e) correlations were detected between systolic and diastolic BP (r g = 0.67 ± 0.12 and r e = 0.48 ± 0.08, P < 0.05). Genetic correlations between BP and TPA were not significant, while a tendency to an environmental cross-trait correlation was found between diastolic BP and TPA (r e = -0.18 ± 0.09, P = 0.057). In conclusion, BP and PA are under genetic influences. Systolic and diastolic BP share common genes and environmental influences. Diastolic BP and TPA are probably under similar environmental influences.

Genetic and environmental influences on blood pressure and physical activity: a study of nuclear families from Muzambinho, Brazil.

Blood pressure (BP) and physical activity (PA) levels are inversely associated. Since genetic factors account for the observed variation in each of these traits, it is possible that part of their association may be related to common genetic and/or environmental influences. Thus, this study was designed to estimate the genetic and environmental correlations of BP and PA phenotypes in nuclear families from Muzambinho, Brazil. Families including 236 offspring (6 to 24 years) and their 82 fathers and 122 mothers (24 to 65 years) were evaluated. BP was measured, and total PA (TPA) was assessed by an interview (commuting, occupational, leisure time, and school time PA). Quantitative genetic modeling was used to estimate maximal heritability (h²), and genetic and environmental correlations. Heritability was significant for all phenotypes (systolic BP: h² = 0.37 ± 0.10, P < 0.05; diastolic BP: h² = 0.39 ± 0.09, P < 0.05; TPA: h² = 0.24 ± 0.09, P < 0.05). Significant genetic (r g) and environmental (r e) correlations were detected between systolic and diastolic BP (r g = 0.67 ± 0.12 and r e = 0.48 ± 0.08, P < 0.05). Genetic correlations between BP and TPA were not significant, while a tendency to an environmental cross-trait correlation was found between diastolic BP and TPA (r e = -0.18 ± 0.09, P = 0.057). In conclusion, BP and PA are under genetic influences. Systolic and diastolic BP share common genes and environmental influences. Diastolic BP and TPA are probably under similar environmental influences.

Motor coordination as predictor of physical activity in childhood.

This study considers relationships among motor coordination (MC), physical fitness (PF) and physical activity (PA) in children followed longitudinally from 6 to 10 years. It is hypothesized that MC is a significant and primary predictor of PA in children. Subjects were 142 girls and 143 boys. Height, weight and skinfolds; PA (Godin-Shephard questionnaire); MC (Körperkoordination Test für Kinder); and PF (five fitness items) were measured. Hierarchical linear modeling with MC and PF as predictors of PA was used. The retained model indicated that PA at baseline differed significantly between boys (48.3 MET/week) and girls (40.0 MET/week). The interaction of MC and 1 mile run/walk had a positive influence on level of PA. The general trend for a decrease in PA level across years was attenuated or amplified depending on initial level of MC. The estimated rate of decline in PA was negligible for children with higher levels of MC at 6 years, but was augmented by 2.58 and 2.47 units each year, respectively, for children with low and average levels of initial MC. In conclusion MC is an important predictor of PA in children 6-10 years of age.

Correlates of physical activity in Portuguese adolescents from 10 to 18 years.

This study examined the association between demographic [age, sex, socioeconomic status (SES)] and socio-cultural [father, mother, sibling physical activity (PA); peers and physical education teacher influences] correlates and low, moderate and high levels of PA among Portuguese adolescents aged 10-18 years. A total of 3352 males and females attending basic and secondary schools, their parents and siblings were sampled across four regions of Portugal. PA was assessed with a psychometrically validated questionnaire. Multinomial logistic regression was used. Age was positively related with moderate and high PA. Boys and adolescents of high SES were more likely to participate in moderate and high PA. Adolescents were more likely to participate in high PA when theirs mother and sibling(s) also participated. Peers had a positive influence on participation in moderate and high PA, while physical education teachers did not have an influence. The results indicated that demographic and socio-cultural correlates--in particular age, sex, SES, mother and sibling PA, and peer influence--were significantly associated with adolescent PA. These results also suggested that interventions should focus on girls and low SES adolescents who face higher risk of inactivity.

A growth curve to model changes in sport participation in adolescent boys.

The aims of this study are twofold: (1) to present the latent growth model, its strategy and usefulness in modelling sport participation over a 6-year period in youngsters (2) and to study the impact of biological maturation in sport participation changes. A standardized sport participation questionnaire using h/week/year as the unit of analysis was applied to 588 Belgium boys 13-18 years of age followed longitudinally for 6 years. Skeletal age was used to estimate biological maturation. Growth curve modelling with robust estimation was used. Sport participation changes showed a curvilinear trend: baseline values (3.18+/-0.13 h/week/year), a linear trend that indicates the rate of change (0.70+/-0.11) and a quadratic trend indicating deceleration, i.e. a change in the rate of change (-0.07+/-0.02) were all statistically significant (P<0.05), as well as inter-individual differences in these three parameters. Up to 16.8 years, the rate of sports participation increased 0.70 h/week/year and then declined. Biological maturation did not show any association with adolescent changes in sport participation.

Habitual physical activity levels in childhood and adolescence assessed with accelerometry.

AIM: The purposes of this study were: 1) to evaluate age and gender differences in physical activity (PA) of children and adolescents; 2) to find out if children and adolescents fulfill the PA recommendations of 60 min x day(-1) of moderate (MPA) to vigorous PA (VPA). METHODS: PA was assessed in 265 female and 238 male subjects, ranging from 6 to 18 years of age, grouped in 4 age groups, with MTI ActiGraph model 7164, during 7 consecutive days. The MTI actigraph data was reduced to bouts (30-, 20-, 10-, and 5-min) and minutes spent in MPA, VPA, and very VPA (VVPA). RESULTS: The oldest boys and girls revealed a lower number of PA bouts than the younger ones. Significant gender differences were found in daily VPA, F(1, 492)=37.67, P<0.001; and VVPA F(1, 494)=24.11, P<0.001. Boys were more active than girls. Significant age group differences were also found in MPA, F(3, 494)=87.4, P<0.001; VPA, F(3, 492)=78.15, P<0.001; and VVPA, F(3, 454)=54.89, P<0.001. In both genders MPA, VPA and VVPA decreased with age. Till the age of 14, children had means between 79.6+/-30.6 and 144.1+/-76.9 min*day(-1) of PA. After this age, there was a decrease to 44.1+/-19.9 min*day(-1) in girls and to 56.3+/-31.9 min*day(-1) in boys. CONCLUSION: Boys had more minutes a day of VPA and VVPA than girls. PA decreased with age. The subjects of this study, aged 6 to 15, fulfilled the recommendations of 60 min x day(-1) of MPA to VPA.