Aristides M. Machado-Rodrigues

Nutritional status, biological maturation and cardiorespiratory fitness in Azorean youth aged 11–15 years

BackgroundSex and individual differences in biological maturity status can influence height, weight, and body fat. Thus, the rigorous control of these variables seems necessary for estimating overweight and obesity in adolescents. The aims of this study were to estimate the prevalence of overweight and obesity and over-fatness in Azorean adolescents and to examine the contributions of chronological age, sex, estimated maturity status, and cardiorespiratory fitness (CRF) to the risk of overweight and obesity and over-fatness.MethodsThe sample comprised 1,206 youth aged 11–15 years (626 boys and 580 girls) from the Azores Islands, Portugal. Body mass, stature, and skinfolds (triceps and subscapular) were measured. Body mass index (BMI) was calculated and percent fat was predicted from skinfolds. Age- and sex-specific IOTF cut-off values of the BMI defined nutritional status. Biological maturation was estimated as present height expressed as a percentage of predicted adult (mature) stature. The CRF was analyzed from the 20-m shuttle run test.ResultsThe total prevalence rates of overweight/obesity and over-fatness were of 31% and 27%, respectively. Low CRF (unfit) and being average and advanced in maturity status were positively and significantly associated with overweight/obesity and with risk of being over-fatness in both sexes.ConclusionsHigh prevalence rates of overweight/obesity and over-fatness were identified in Azorean youth, and low CRF and advanced biological maturation were positively associated with overweight/obesity and over-fatness in our sample of adolescents.

Urban - rural contrasts in fitness, physical activity, and sedentary behaviour in adolescents

Research considering physical activity (PA), physical inactivity and health outcomes among urban and rural youth has produced equivocal findings. This study examined PA, physical inactivity, sedentary behaviours and cardiorespiratory fitness (CRF) in adolescents from urban and rural communities in the Portuguese Midlands. The sample included 362 adolescents (165 males, 197 females) of 13-16 years of age. CRF was assessed by the PACER test. A GT1M accelerometer was used to record 5 consecutive days of PA and time spent sedentary. Analyses of covariance (chronological age as co-variate) were performed to test the effect of the area of residence on sedentary behaviour, PA and CRF. Urban youth of both sexes spent less time in sedentary activities than rural youth. Urban males were more active than rural peers at the weekend, whereas urban females were significantly less active than rural females on week days and across all days assessed. Rural youth of both sexes had higher levels of CRF than urban youth. Area of residence was related to aerobic fitness, PA and time spent in sedentary behaviours among Portuguese youth. Interventions seeking to enhance health and active lifestyles in Portuguese youth should consider the potential impact of socio-geographic factors.

Cardiorespiratory fitness, weight status and objectively measured sedentary behaviour and physical activity in rural and urban Portuguese adolescents.

Relationships among weight status (body mass index [BMI]), cardiorespiratory fitness (CRF) and objective measures of sedentary behaviour and physical activity (PA) were considered in a cross-sectional sample of Portuguese adolescents. The sample included 362 youth aged 13–16 years (165 males, 197 females) from urban and rural regions of the Portuguese midlands. CRF was assessed with the 20-m shuttle-run test. An uniaxial accelerometer was used to obtain five consecutive days of activity behaviours including time being sedentary. Pearson correlations and logistic regression analysis were used to examine relationships among variables. Rural adolescents were less active than their urban peers over the weekend. Both rural and urban youth with higher levels of CRF had a lower relative risk of being overweight/obese. The observations indicate important associations between weight status and CRF in both rural and urban Portuguese adolescents. In addition, place of residence has an important impact on weight status of this sample of adolescents.

Agreement in activity energy expenditure assessed by accelerometer and self-report in adolescents: variation by sex, age, and weight status.

Abstract The agreement between self-reported and objective estimates of activity energy expenditure was evaluated in adolescents by age, sex, and weight status. Altogether, 403 participants (217 females, 186 males) aged 13–16 years completed a 3-day physical activity diary and wore a GT1M accelerometer on the same days. Partial correlations (controlling for body mass) were used to determine associations between estimated activity energy expenditure (kcal · min−1) from the diary and accelerometry. Differences in the magnitude of the correlations were examined using Fishers r to z transformations. Bland–Altman procedures were used to determine concordance between the self-reported and objective estimates. Partial correlations between assessments of activity energy expenditure (kcal · min−1) did not differ significantly by age (13–14 years: r = 0.41; 15–16 years: r = 0.42) or weight status (normal weight: r = 0.42; overweight: r = 0.39). The magnitude of the association was significantly affected by sex (Δr = 0.11; P < 0.05). The agreement was significantly higher in males than in females. The relationship between activity energy expenditure assessed by the objective method and the 3-day diary was moderate (controlling for weight, correlations ranged between 0.33 and 0.44). However, the 3-day diary revealed less agreement in specific group analyses; it markedly underestimated activity energy expenditure in overweight/obese and older adolescents. The assessment of activity energy expenditure is complex and may require a combination of methods.

Independent association of clustered metabolic risk factors with cardiorespiratory fitness in youth aged 11-17 years.

Abstract Background: Although the prevalence of metabolic syndrome (MetS) has increased in youth, the potential independent contribution of cardiorespiratory fitness (CRF) to the clustering of metabolic risk factors has received relatively little attention. Aim: This study evaluated associations between the clustering of metabolic risk factors and CRF in a sample of youth. Subjects and methods: Height, weight, BMI, fasting glucose, insulin, HDL-cholesterol, triglycerides and blood pressures were measured in a cross-sectional sample of 924 youth (402 males, 522 females) of 11–17 years. CRF was assessed using the 20-metre shuttle run test. Physical activity (PA) was measured with a 3-day diary. Outcome variables were statistically normalized and expressed as Z-scores. A MetS risk score was computed as the mean of the Z-scores. Multiple linear regression was used to test associations between CRF and metabolic risk, adjusted for age, sex, BMI, PA and parental education. Results: CRF was inversely associated with MetS after adjustment for potential confounders. After adjusting for BMI, the relationship between CRF and metabolic risk has substantially improved. Conclusion: CRF was independently associated with the clustering of metabolic risk factors in youth of 11–17 years of age.

Concurrent validation of estimated activity energy expenditure using a 3‐day diary and accelerometry in adolescents

Estimates of daily energy expenditure are important to studies of physical activity and energy balance. Objective measures are not always feasible and further research is needed to validate survey instruments and diaries. The study validates estimated activity energy expenditure (AEE) based on a 3‐day diary protocol relative to AEE derived from uniaxial accelerometry in adolescents, 265 girls and 227 boys (12.5–16.4 years). Participants completed the diary and wore a GT1M Actigraph accelerometer on the same days. Height and weight were measured. Correlations between protocols were significant (P<0.001) but moderate, r=0.65 in males and r=0.69 in females. The highest correlation occurred among males on Friday, r=0.74 (P<0.01). Controlling for body mass, partial correlations between protocols decreased to 0.44 and 0.35 in males and females, respectively. About 97% of the cases fell within the limits of agreement in a Bland–Altman plot. The criterion of inclusion for the accelerometer excluded 18% of the initial sample. In summary, the 3‐day diary was completed without any major problems and provided a reasonably valid alternative for assessing AEE. Concordance between methods was slightly lower for individuals with higher values of AEE.

Correlates of aerobic fitness in urban and rural Portuguese adolescents

Background: Improving physical fitness is often an objective of programmes aimed at preventing obesity among youth. Aim: To evaluate the association between cardiorespiratory fitness (CRF) and area of residence controlling for several correlates in adolescents. Subjects and methods: CRF was assessed with the progressive aerobic cardiovascular endurance run (PACER) test in a cross-sectional sample of 362 Portuguese adolescents (165 males, 197 females) of 13–16 years of age. Youth were classified by area of residence as urban or rural. Gender, age, weight status, parental education, screen time (inactivity) and moderate-to-vigorous physical activity (MVPA) were statistically controlled. Logistic regression analysis was used. Results: Adolescents of both sexes from rural settings were 76% more likely to be classified as aerobically fit compared to those from urban areas. The odds ratio for CRF in the final model was similar in boys (OR = 0.24, 95% CI 0.06–0.99, p < 0.05) and girls (OR = 0.24, 95% CI 0.07–0.76, p < 0.05). MVPA and weight status were important predictors of CRF in Portuguese adolescents of 13–16 years of age. Maternal education was an additional predictor in girls. Conclusion: CRF and rural/urban settings were significantly related in this sample of Portuguese adolescents of both sexes.

Active commuting and its associations with blood pressure and adiposity markers in children.

OBJECTIVE The positive impacts of active travel on health markers still require further research, especially in youth populations with higher risk of obesity. The present study aimed to analyze the associations between blood pressure and adiposity risk (BPAR) and active travel to school in children. METHODS The sample comprised 665 Portuguese children (345 boys) aged 7-9 years. Data on height, weight, and skinfold thickness were collected by a trained fieldworker as well as data on BPAR between March 2009 and January 2010 (data were analyzed in 2012-2013). Information on mode and duration of travel to school (i.e. exposure) was gathered by questionnaire. Outcome variables were statistically normalized and expressed as Z scores. A BPAR score was computed as the mean of the Z scores. Multiple linear regression, with adjustments for confounders, was used. RESULTS Active commuting was inversely associated with BPAR after adjustment for several potential confounders. After adjusting for BMI, the strength of the relationship between BPAR and active commuting was significantly improved (p≤0.01). CONCLUSIONS Findings showed an independent association between the clustered BPAR and active commuting in children aged 7-9 years.

Parental perceptions of neighborhood environments, BMI, and active behaviors in girls aged 7-9 years.

Habitual physical activity (PA) may be influenced by a broad range of neighborhood, school, community, and family factors. Young people, particularly girls, tend to show lower habitual PA than boys and should be a target for prevention strategies aimed at healthy lifestyles. The purpose of this study was twofold: (1) to determine which perceived attributes about neighborhoods are related to active behaviors; (2) to analyze which perceived attributes about neighborhoods are related to body mass index (BMI) of children.

The Mediating Role of Physical Inactivity on the Relationship between Inflammation and Artery Thickness in Prepubertal Adolescents

OBJECTIVE To analyze the relationship between inflammatory markers and the lipid profile, blood flow, and artery structure in prepubertal adolescents stratified according to sports practice. STUDY DESIGN The sample was composed of 120 adolescents (57 boys and 63 girls) with a mean age of 11.7 ± 0.7 years (ranging from 11 to 13 years). Intima-media thickness (IMT) and blood flow were measured with ultrasonography. The lipid profile and high-sensitivity C-reactive protein were measured after the subjects had fasted for 12 hours overnight. Trunk fatness was measured by dual-energy x-ray absorptiometry. Organized sports participation was analyzed as a categorical variable. Biological maturation was determined via the age at peak height velocity. RESULTS In the adjusted model, high-sensitivity C-reactive protein was significantly related to high-density lipoprotein-cholesterol (β = -5.797 [-11.500 to -0.093]), femoral IMT (β = 0.062 [0.008-0.116]), and the sum of femoral and carotid IMT (β = 1.107 [0.223-1.919]), but only in the group without sports participation. Slopes of the crude linear regression were greater in the group without sports participation for femoral IMT (t = 2.621; P = .009) and the sum of femoral and carotid IMT (t = 2.876; P = .004) when compared with the group with sports participation. CONCLUSION Independent of body fatness and biological maturation, inflammatory status was related to artery IMT and dyslipidemia in prepubertal adolescents, modulated by sport participation.