Exploring Perceived Barriers to Physical Activity among Older Adults Living in Low-Population Density Regions: Gender Differences and Associations with Activity Dimensions.

Older people in low-population density regions tend to have fewer resources to engage in regular physical activity (PA) compared to their counterparts in urban areas. Moreover, PA assumes different dimensions, and the amount of PA related to each dimension may differ between women and men, predisposing them to different PA practices. Therefore, this cross-sectional study aims to describe the prevalence of barriers to PA, gender differences, and their associations with different PA dimensions. A total of 259 older adults (153 women and 106 men; age, 75.17 ± 8.05 years old) living in the community in the region of Guarda (Portugal) were interviewed face to face to record their sociodemographic characteristics, general health status (comorbidity index and self-reported health), PA behaviour, and barriers to PA. Women were more likely to report "low" income and living alone (p ≤ 0.05), while men reported a higher negative health status than women (p < 0.05). Two intrinsic ("Fear of injury" (40.1%) and "Need for rest" (26.3%)) and two extrinsic barriers ("Lack of nearby facilities" (30.5%) and "I don't have transport" (25.6%)) were the most prevalent. For women, age, self-reported health, comorbidity index, and intrinsic and extrinsic barriers were similarly associated with the different PA dimensions. However, only self-reported health and extrinsic barriers were the variables associated with the different PA dimensions in men. Therefore, strategies to promote active ageing in low-population density regions should be focused on reducing intrinsic and extrinsic barriers based on gender and the PA dimension to be achieved.

The Mediation Role of Perceived Benefits and Barriers in the Relationship Between Support Provided by Significant Others and Physical Activity of Adolescents.

We investigated whether the relationship between significant others' social support and adolescents' physical activity (PA) is mediated by perceived barriers and benefits of PA. In this cross-sectional study, we analyzed data from 497 adolescents (girls = 272, boys = 225) aged between 12-18 years (M = 15.87, SD = 1.43) from six different middle and secondary schools. We collected data regarding social cognitive variables and PA with self-report measures and calculated the metabolic equivalent of total amount PA. We performed structural equation modeling and mediation analyses and found our proposed models fit the data. In girls, perceived PA benefits mediated the association between support provided by friends (ß = .13; IC 95% = .02 .29), a best friend (ß = .14; IC 95% = .03, .33), and parents (ß = .07; IC 95% = .01, .18), and PA. Similarly in boys, perceived PA benefits partially mediated the association between support provided by parents (ß = .09; IC 95% = .04, .37), friends (ß = .11; IC 95% = .05, .40), and a best friend (ß = .10; IC 95% = .05, .40) and PA. Perceived barriers to PA did not display any significant mediation role for either sex. Interventions to foster others' support for PA, especially from a best friend, are important for promoting PA among adolescents.

Potential relevance of a motor skill "proficiency barrier" on health-related fitness in youth.

This study investigated the potential impact of a motor skill proficiency barrier on measures of cardiorespiratory (CRF) and musculoskeletal (MSF) fitness in youth. A sample of 241 youth (114 girls) aged 10 - 18 years, completed the Motor Competence Assessment battery with composite scores indexed according to age- and gender-adjusted percentile scores. Motor competence (MC) levels were categorized as low (≤ 25%tile - proficiency barrier), moderate (≥ 26%tile to < 75%tile), and high (≥ 75%tile). CRF levels (Health Risk, Needs Improvement, and Healthy) were assessed using the Fitnessgram® 20 m PACER test. Low (≤ 20%tile), moderate (≥ 21%tile to ≤ 80%tile), and high (≥ 80%tile) MSF levels were assessed using grip strength normative data. Two 3 × 3 chi-square tests were conducted to determine the probability of MC level predicting CRF and MSF levels. Results demonstrated statistically significant models for performance on both the PACER (χ2[4, N = 241] = 22.65, p < .001) and grip strength (χ2[4, N = 241] = 23.95, p < .001). Strong evidence of a proficiency barrier impacting CRF was noted, as no low skilled youth met the "Healthy" fitness zone standards for PACER performance. Evidence supporting a barrier with grip strength was not as strong, as 20.8% of youth exhibiting low MC displayed high grip strength. However, all individuals with high levels of MC demonstrated at least moderate grip strength. Results emphasize the importance of developing MC during childhood as it may provide a protective effect against unhealthy CRF and MSF across youth.HighlightsThese data support the notion of Seefeldt's (1980) proficiency barrier as it relates to CRF, as no youth demonstrating low MC met the healthy fitness zone criteria for PACER performance. The development of MC may both directly and indirectly provide a protective effect against unhealthy CRF levels across childhood and adolescence.Evidence supporting a proficiency barrier with MSF as measured by grip strength was not as strong; however, all individuals with high levels of MC demonstrated at least moderate grip strength. Thus, the development of MC may be a protective factor to mitigate low levels of MSF via enhanced neuromuscular function.Promoting the development of MC in a variety of developmentally appropriate activities and settings (e.g. MC skills practice, structured and unstructured play, and performance contexts) is important to promote positive trajectories of CRF and MSF across childhood and adolescence.

Motor Competence Assessment (MCA) Scoring Method.

The Motor Competence Assessment (MCA) is a quantitative test battery that assesses motor competence across the whole lifespan. It is composed of three sub-scales: locomotor, stability, and manipulative, each of them assessed by two different objectively measured tests. The MCA construct validity for children and adolescents, having normative values from 3 to 23 years of age, and the configural invariance between age groups, were recently established. The aim of this study is to expand the MCA's development and validation by defining the best and leanest method to score and classify MCA sub-scales and total score. One thousand participants from 3 to 22 years of age, randomly selected from the Portuguese database on MC, participated in the study. Three different procedures to calculate the sub-scales and total MCA values were tested according to alternative models. Results were compared to the reference method, and Intraclass Correlation Coefficient, Cronbach's Alpha, and Bland-Altman statistics were used to describe agreement between the three methods. The analysis showed no substantial differences between the three methods. Reliability values were perfect (0.999 to 1.000) for all models, implying that all the methods were able to classify everyone in the same way. We recommend implementing the most economic and efficient algorithm, i.e., the configural model algorithm, averaging the percentile scores of the two tests to assess each MCA sub-scale and total scores.

The Developmental Trajectory of Motor Competence of Children That Lived the COVID-19 Confinement Period: A Four-Year Follow-Up Study in Portuguese Children.

Children's motor competence (MC) was negatively affected by the COVID-19 pandemic; however, possible chronic effects have not been studied. Therefore, the aim of this study was to examine the possible impact of the forced lack of physical activity (PA) during the COVID-19 lockdown on children's MC two years later. The motor competence of sixty-seven healthy children (7.4−12.2 years old) was assessed using the Motor Competence Assessment (MCA). All participants completed the MCA tests at two different moments (before and after the COVID-19 lockdown), four years apart. The mean values after the COVID-19 lockdown for all participants on the subscales and on the Total MCA are lower, but no significant changes were found when controlling for gender and age (p > 0.05 in all analyses). However, a significant decrease was found in the Locomotor subscale in boys (p = 0.003). After dividing the participants into three age groups, the youngest also suffered a decrease in the Locomotor subscale (p < 0.001) and their Total MCA (p = 0.04). In addition, those participants who had a higher MC at baseline decreased their scores for the Locomotor (p < 0.001) and Manipulative (p < 0.001) subscales, and for the Total MCA (p < 0.001). In conclusion, the younger children and the more motor proficient did not fully recover from the negative effects of the pandemic lockdown after two years.

Variación en la actividad física, condición física y competencia motora según el estado de peso de jóvenes de 12-15 años de Cabo Verde / Variação da atividade física, aptidão e competência motora de acordo com o estatuto ponderalde jovens de 12-15 anos de Cabo Verde / Variation in physical activity, fitness and motor competence according to weight status of 12-15 years youngsters from Cabo Verde

El objetivo: evaluar la actividad física (AF), aptitud física (ApF) y competencia motora (CM) entre jóvenes caboverdianos en relación con el estado de peso. La altura, peso, ApF (fuerza de prensión, flexiones de brazos, abdominales, sentarse-alcanzar, una milla de carrera/caminata), CM (KTK) yAF (podómetros) se midieron en 343 niños y niñas de 12-14 años. Se utilizó ANCOVA. AF y CM no variaron consistentemente con el estado de peso. La aptitud cardiorrespiratoria y la fuerza de prensión de las niñas delgadas fueron significativamente mejores que las de peso normal y con sobrepeso/obesidad. Los niños con bajo peso se desempeñaron significativamente mejor que los niños normales y con sobrepeso/obesidad. En conclusión, las diferencias entre los jóvenes por estado de peso no fueron evidentes, excepto en la aptitud cardiorrespiratoria en las niñas y la fuerza de prensión en ambos sexos. CM se diferenciaba por el estado de peso solo entre las niñas. (AU)

Aim: evaluate physical activity (PA), physical fitness (PF) and motor competence (MC) relative weight status among Cabo Verde youth. Height and weight were measured in 343 boys and girls 12-14 years. PF tests included grip strength, push-ups, curl-ups, sit-and-reach, one-mile-run/walk. KTK tests were the indicator of MC. PA was estimated with pedometers. ANCOVA was used. PA and MC did not vary consistently with weight status. Cardiorespiratory fitness and grip strength per unit mass of thin girls was significantly better than normal weight and overweight/obese girls. Underweight boys performed significantly better in grip strength per unit mass than normal and overweight/obese boys. In conclusions, differences among youth by weight status were not apparent except for the one-mile run in girls and grip strength per unit body mass in both sexes. MC differed by weight status only among girls. (AU)

Objetivo: avaliar a atividade física (AF), aptidão física (ApF) e competência motora (CM) em jovens cabo-verdianos de acordo com o estatuto ponderal. Altura, peso, ApP (força de preensão, flexões de braços, elevações do tronco, sentar-alcançar, correr/caminhar uma milha), CM (bateria KTK) e AF (pedómetros) foram medidos em 343 meninos e meninas de 12-14 anos. ANCOVA foi usada. A AF e CM não variaram com o estatuto ponderal. Aptidão cardiorrespiratória e força de preensão de meninas magras foram melhores do que a das meninas com peso normal e com sobrepeso/obesidade. Rapazes com baixo peso tiveram desempenho melhor na força de preensão do que rapazes normais e com sobrepeso/obesidade. Conclusão, as diferenças entre os jovens por estatuto ponderal não foram evidentes, exceto para a corrida de uma milha em meninas e força de preensão por unidade de massa corporal em ambos os sexos. MC diferiu por estatuto ponderal apenas entre as meninas. (AU)

How does 11-week detraining affect 11-12 years old swimmers' biomechanical determinants and its relationship with 100 m freestyle performance?

The aim of this study was to analyse the detraining process that occurs during a season break, and its influence on the performance, anthropometrics, and biomechanics of young swimmers. The sample included 54 young swimmers (22 boys: 12.79 ± 0.71 years; 32 girls: 11.78 ± 0.85 years). Performance for the 100 m freestyle and anthropometric and biomechanical variables were evaluated as main determinants. Performance impaired significantly for boys (2.17%) and girls (1.91%). All anthropometric variables increased between moments of assessment for boys and girls. Overall, the boys enhanced all biomechanical variables during the detraining period, and girls showed mixed results. For both sexes, the stroke index was the variable with the highest increase (boys: Δ = 16.16%; d = 0.89; p = 0.001; girls: Δ = 19.51%; d = 1.06; p = 0.002). Hierarchical linear modelling showed that the height retained the amount of impairment in the performance. One unit of increase in the height (cm) led to less 0.41 s impairment in the performance. Present data indicated that during an 11-weeks detraining period, young swimmers impaired their performance, but the determinant factors showed an impaired relationship. This increase in the determinant factors is mainly related to the increase in the swimmers' anthropometrics. Moreover, the increase in height was responsible for retaining the performance impairment.

Through the Looking Glass: A Systematic Review of Longitudinal Evidence, Providing New Insight for Motor Competence and Health.

INTRODUCTION: In 2008, a conceptual model explaining the role of motor competence (MC) in children's physical activity (PA), weight status, perceived MC and health-related fitness was published. OBJECTIVE: The purpose of the current review was to systematically compile mediation, longitudinal and experimental evidence in support of this conceptual model. METHODS: This systematic review (registered with PROSPERO on 28 April 2020) was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. Separate searches were undertaken for each pathway of interest (final search 8 November 2019) using CINAHL Complete, ERIC, Medline (OVID), PsycINFO, Web of Science Core Collection, Scopus and SportDiscus. Potential articles were initially identified through abstract and title checking (N = 585) then screened further and combined into one review (n = 152), with 43 articles identified for extraction. Studies needed to be original and peer reviewed, include typically developing children and adolescents first assessed between 2 and 18 years and objective assessment of gross MC and at least one other variable (i.e., PA, weight status, perceived MC, health-related fitness). PA included sport participation, but sport-specific samples were excluded. Longitudinal or experimental designs and cross-sectional mediated models were sought. Strength of evidence was calculated for each pathway in both directions for each domain (i.e., skill composite, object control and locomotor/coordination/stability) by dividing the proportion of studies indicating a significantly positive pathway in the hypothesised direction by the total associations examined for that pathway. Classifications were no association (0-33%), indeterminate/inconsistent (34-59%), or a positive '+' or negative ' - ' association (≥ 60%). The latter category was classified as strong evidence (i.e., ++or --) when four or more studies found an association. If the total number of studies in a domain of interest was three or fewer, this was considered insufficient evidence to make a determination. RESULTS: There was strong evidence in both directions for a negative association between MC and weight status. There was strong positive evidence for a pathway from MC to fitness and indeterminate evidence for the reverse. There was indeterminate evidence for a pathway from MC to PA and no evidence for the reverse pathway. There was insufficient evidence for the MC to perceived MC pathway. There was strong positive evidence for the fitness-mediated MC/PA pathway in both directions. There was indeterminate evidence for the perceived MC-mediated pathway from PA to MC and no evidence for the reverse. CONCLUSION: Bidirectional longitudinal associations of MC with weight status are consistent with the model authored by Stodden et al. (Quest 2008;60(2):290-306, 2008). However, to test the whole model, the field needs robust longitudinal studies across childhood and adolescence that include all variables in the model, have multiple time points and account for potential confounding factors. Furthermore, experimental studies that examine change in MC relative to change in the other constructs are needed. TRIAL REGISTRATIONS: PROSPERO ID# CRD42020155799.

Socio-Cultural and Somatic Factors Associated with Children's Motor Competence.

The purpose of this study was to assess the effect of somatic and socio-cultural factors on children's motor competence (MC). MC was assessed through the standing long jump (SLJ), distance throw of a tennis ball (TTB), and 20 m dash (20 m) in 181 children (84 girls) with a mean age of 6.10(0.47) years. The effect of socio-economic status, house/living space, educational practices, the child's interaction with peers and siblings, and the sum of five skinfolds (SS) were analysed via structural equation modelling (SEM) in each motor skill. The SEM models displayed a good fit to the data. In addition, standardized direct effects are significant on different outcome variables, except for brotherhood relationship (BR) and peer relationship in TTB, and 20 m dash and BR in standing long jump (SLJ). SS are negatively related to all motor skills.

Model invariance of the Motor Competence Assessment (MCA) from early childhood to young adulthood.

The Motor Competence Assessment (MCA) is an innovative instrument to assess motor competence along the lifespan. The MCA model and normative values were recently established from the age of 3-to-23 years old. The purpose of this study was to validate MCA from early childhood to young adulthood.One thousand participants representing four age groups (3-6, 7-10, 11-16, 17-22 years) with 250 participants each, were assessed. Invariance of the MCA model along the age groups - configural, metric and structural - was tested using multigroup CFA.The MCA model showed to fit well all age groups. The multigroup unconstrained model showed a very good fit (NFI=0.99; TLI=0.99; CFI=0.99; RMSEA=0.03). A formal test for the invariance of loading coefficients returned a non-satisfactory goodness-of-fit adjustment and a significant difference with the unconstrained model (Δχ2 = 539.57; Δdf = 18; p= .00) . The structural invariance testing did not show formal invariance between factor correlations (Δχ2 = 73.04; Δdf = 9; p= .00) but the fit of the model was acceptable (above 0.96 and a RMSEA of 0.05), indicating that correlation values inter factors are stable.This study adds information for the validation of the MCA as a useful instrument for assessing motor competence throughout the life cycle.

Propulsive Force of Upper Limbs and its Relationship to Swim Velocity in the Butterfly Stroke.

The aims of this study were to: (1) verify the sex effect; (2) assess upper limb asymmetry in anthropometrics and propulsive force variables; and (3) identify the main determinants of butterfly swim velocity based on a set of anthropometrics, kinematics, and propulsive force variables. Twenty swimmers (10 males: 15.40±0.30 years; 10 females: 14.43±0.23 years) at the national level were recruited for analysis. A set of anthropometrics, kinematics, and propulsive force variables were measured. Overall, a significant sex effect was verified (p≤0.05). Non-significant differences between upper-limbs were noted for males and females in all variables, except for the dF in males (t=-2.66, p=0.026, d=0.66). Stroke frequency presented the highest contribution, where a one unit increase in the stroke frequency imposed an increase of 0.375 m·s-1 (95CI: 0.105;0.645, p=0.010) in the swim velocity. The swim velocity was predicted by the mean propulsive force, intra-cyclic variation of the swim velocity, and stroke frequency. Overall, swimmers exhibit non-significant differences in the variables assessed. Swim velocity in the butterfly stroke was determined by an interaction of propulsive force and kinematic variables in young swimmers.

Siblings' Influence on the Motor Competence of Preschoolers.

The number of single-child families has been rising steadily in recent years, resulting in a childhood absent of sibling relationships. Being an only child has been shown to have a negative impact on physical fitness, somatic fitness, and motor development. In this study, we aimed to understand how living with and without siblings can impact the motor competence of children. One hundred and sixty-one children (87 boys, 74 girls) from 3.0 to 6.0 years of age (34 only children, 125 siblings) and with no known motor or cognitive disability were assessed using the Motor Competence Assessment (MCA). Their standardized results on the three MCA subscales (stability, locomotor, and manipulative) and total MCA were used to group them into high, average, and low motor competence groups. Motor competence percentile distribution of the sibling and only child group condition was compared using chi-square tests. Results showed a significative and positive association between the sibling condition and the distribution between the three MC groups (chi-square = 6.29; p = 0.043), showing that children in a household with siblings, independent of their age and sex, show a clear tendency for developing better motor competence.

Developmental pathways of cardiorespiratory fitness from 6 to 15 years of age.

Most of the information gathered about physical fitness of paediatric populations are cross-sectional, resulting in normative perspectives that account for average values relative to age, but not to a comprehensive understanding of developmental individual trajectories. The aim of this study was to model the longitudinal development of cardiorespiratory fitness of boys and girls from 6 to 15 years of age, using an individual centred approach. Two hundred twenty-nine school children (128 boys; 101 girls) were followed on their 20 metres shuttle run test (20mSRT) results from 6 to 15 years of age. Annual measurements were made during the four years of primary school, and again at grade 9th or 10th. Individual trajectories of 20mSRT development were modelled and grouped according to their similarities of change in three different developmental pathways that were included in subsequent hierarchical nested models for testing each sex developmental model of cardiorespiratory fitness. Final models including the developmental pathways showed better deviance statistics (p < .001). Interindividual slope variances were almost zero, and statistically non-significant (0.05 boys 0.01 girls; p > .50), meaning these models capture well the existing variability, in respect to the rate of change. Individual pathways of change in the performance of 20mSRT test can be detected in childhood and adolescence. Additionally, all individual's developmental trajectories in 20mSRT can be described using three significantly different slopes. These pathways are indicative of a high, average, or low rate of change in performance over the years and differ from the normative approach.

The Influence of the Coaches' Demographics on Young Swimmers' Performance and Technical Determinants.

The purpose of this study was to understand the relationship between the coaches' demographics (academic degree and/or coaching level and/or coaching experience) and young swimmers' performance and technical ability. The sample was composed by 151 young swimmers (75 boys and 76 girls: 13.02 ± 1.19 years old, 49.97 ± 8.77 kg of body mass, 1.60 ± 0.08 m of height, 1.66 ± 0.09 m of arm span), from seven different clubs. Seven coaches (one per club) were responsible for the training monitoring. Performance and a set of biomechanical variables related to swim technique and efficiency were assessed. The swimmers' performance was enhanced according to the increase in the coaches' academic degree (1: 75.51 ± 10.02 s; 2: 74.55 ± 9.56 s; 3: 73.62 ± 7.64 s), coaching level (1: 76.79 ± 11.27 s; 2: 75.06 ± 9.31 s; 3: 73.65 ± 8.43 s), and training experience (≤5-y training experience: 75.44 ± 9.57 s; >5-y training experience: 74.60 ± 9.54 s). Hierarchical linear modeling retained all coaches' demographics characteristics as main predictors (being the academic degree the highest: estimate = -1.51, 95% confidence interval = -0.94 to -2.08, p = 0.014). Hence, it seems that an increase in the demographics of the coaches appears to provide them with a training perspective more directed to the efficiency of swimming. This also led to a higher performance enhancement.

Classes of developmental trajectories of body mass index: Differences in motor competence and cardiorespiratory fitness.

The purpose was to identify classes of different developmental trajectories of BMI and testing them for differences in motor competence (MC) and cardiorespiratory fitness (CRF), in children and adolescents (4 to 13 years of age). This was a 5 years' longitudinal study with six cohorts. One hundred and forty-seven children (69 girls) divided into six cohorts participated. At baseline, the youngest and the oldest cohorts had 4 and 11 years of age, respectively. Height and weight were assessed, and BMI was calculated. MC was assessed with KTK and TGMD-2, and CRF was assessed with one-mile run/walk. Developmental trajectories of BMI were identified using latent class linear-mixed modelling. Latent class membership was explained according to covariates of MC and CRF. Two meaningful classes were identified. Class 1 (78.92% of the participants) showed lower initial BMI and a lower slope compared to class 2 (21.08% of the participants) (all ps < 0.001). Class membership only predicted trajectories in motor coordination, with children in class 1 having a better development.In conclusion, this study identified two meaningful trajectories for children based on their BMI development across five time points. In line with previous research, children with slower increasing BMI showed better motor coordination improvements.

Comparison of motor competence in children aged 6-9 years across northern, central, and southern European regions.

The present study aimed to examine differences in motor competence (MC) in children aged 6-9 years old in northern, central, and southern European regions using the Körperkoordinationstest für Kinder (KTK). The secondary aim of the study was to examine interactions between region and children's age, sex, and weight status (determined as healthy weight or overweight/obese). Data were pooled from independent studies conducted in Finland (mean age 7.81 ± 1.19 years, n = 690), Belgium (mean age 8.25 ± 1.09 years, n = 1896), and Portugal (mean age 8.31 ± 1.02 years, n = 758) between 2008 and 2016. Cross-cultural differences in MC and interaction effects were tested using ANOVAs and ANCOVAs. Age, sex, and BMI percentile were used as covariates. Geographical region significantly explained 19% of the variance in MC, while BMI (5%), sex (3%), and age (0.3%) were significant covariates. The interaction effect of region and age (5%), region and sex (0.6%), and region and BMI (0.2%) on MC was also significant. Cross-cultural differences in children's MC increased substantially across age, independent of weight status. Girls slightly underperformed in MC compared to boys in regions where the overall level of MC was lower. Interestingly, the association between body weight status and MC was relatively consistent across the regions. Future cross-cultural studies should further explore the influence of individual (eg, physical activity) and environmental (eg, physical activity and sport policy) factors on MC development.

Body mass index and physical fitness in Brazilian adolescents / Índice de massa corporal e aptidão física em adolescentes brasileiros

Abstract Objective: Evaluate the relationship between body mass index and physical fitness in a cross-sectional sample of Brazilian youth. Methods: Participants were 3849 adolescents (2027 girls) aged 10 -17 years. Weight and height were measured; body mass index was calculated. Physical fitness was evaluated with a multistage 20 m shuttle run (cardiovascular endurance), standing long jump (power), and push-ups (upper body strength). Participants were grouped by sex into four age groups: 10 -11, 12 -13, 14 -15, and 16 -17 years. Sex-specific ANOVA was used to evaluate differences in each physical fitness item among weight status categories by age group. Relationships between body mass index and each physical fitness item were evaluated with quadratic regression models by age group within each sex. Results: The physical fitness of thin and normal youth was, with few exceptions, significantly better than the physical fitness of overweight and obese youth in each age group by sex. On the other hand, physical fitness performances did not consistently differ, on average, between thin and normal weight and between overweight and obese youths. Results of the quadratic regressions indicated a curvilinear (parabolic) relationship between body mass index and each physical fitness item in most age groups. Better performances were attained by adolescents in the mid-range of the body mass index distribution, while performances of youth at the low and high ends of the body mass index distribution were lower. Conclusion: Relationships between the body mass index and physical fitness were generally nonlinear (parabolic) in youth 10 -17 years.

Resumo Objetivo: Avaliar a relação entre o índice de massa corporal e a aptidão física em uma amostra transversal de jovens brasileiros. Métodos: Os participantes foram 3.849 adolescentes (2.027 meninas) entre 10-17 anos. Foram medidos o peso e a estatura e foi calculado o índice de massa corporal. A aptidão física foi avaliada com: a corrida vaivém de 20 metros de vários estágios (resistência cardiovascular), impulsão horizontal (energia) e flexões (força superior do corpo). Os participantes foram agrupados por sexo em quatro faixas etárias: 10-11, 12-13, 14-15 e 16-17 anos. A Anova específica para sexo foi usada para avaliar as diferenças em cada item de aptidão física entre as categorias de status do peso por faixa etária. As relações entre o índice de massa corporal e cada item de aptidão física foram avaliadas com os modelos de regressão quadrática por faixa etária com relação ao sexo. Resultados: A aptidão física de jovens magros e normais foi, com poucas exceções, significativamente melhor do que a aptidão física de jovens com sobrepeso e obesos em cada faixa etária por sexo. Por outro lado, os desempenhos na aptidão física não diferiram de forma consistente, em média, entre jovens magros e com peso normal e entre jovens com sobrepeso e obesos. Os resultados das regressões quadráticas indicaram uma relação curvilínea (parabólica) entre o índice de massa corporal e cada item de aptidão física na maior parte das faixas etárias. Os melhores desempenhos foram obtidos pelos adolescentes na faixa intermediária da distribuição do índice de massa corporal, ao passo que os desempenhos dos jovens nas extremidades inferiores e superiores da distribuição do índice de massa corporal foram menores. Conclusão: As relações entre o índice de massa corporal e a aptidão física foram, em geral, não lineares (parabólica) nos jovens entre 10-17 anos.

Body mass index and physical fitness in Brazilian adolescents.

OBJECTIVE: Evaluate the relationship between body mass index and physical fitness in a cross-sectional sample of Brazilian youth. METHODS: Participants were 3849 adolescents (2027 girls) aged 10-17 years. Weight and height were measured; body mass index was calculated. Physical fitness was evaluated with a multistage 20m shuttle run (cardiovascular endurance), standing long jump (power), and push-ups (upper body strength). Participants were grouped by sex into four age groups: 10-11, 12-13, 14-15, and 16-17 years. Sex-specific ANOVA was used to evaluate differences in each physical fitness item among weight status categories by age group. Relationships between body mass index and each physical fitness item were evaluated with quadratic regression models by age group within each sex. RESULTS: The physical fitness of thin and normal youth was, with few exceptions, significantly better than the physical fitness of overweight and obese youth in each age group by sex. On the other hand, physical fitness performances did not consistently differ, on average, between thin and normal weight and between overweight and obese youths. Results of the quadratic regressions indicated a curvilinear (parabolic) relationship between body mass index and each physical fitness item in most age groups. Better performances were attained by adolescents in the mid-range of the body mass index distribution, while performances of youth at the low and high ends of the body mass index distribution were lower. CONCLUSION: Relationships between the body mass index and physical fitness were generally nonlinear (parabolic) in youth 10-17 years.

Linear and nonlinear relationships between body mass index and physical fitness in Brazilian children and adolescents.

OBJECTIVES: The purpose of this study was to evaluate the linear and curvilinear relationship between body mass index (BMI) and physical fitness in children and adolescents. METHODS: Participants were 4567 (2505 girls) children aged 6-16 years. Weight and height were measured and BMI was calculated and adjusted for age and sex using WHO z-scores. Physical fitness was evaluated with the following tests: Yo-Yo test, standing long jump, seated 2-kg medicine ball throw, and 20-m dash. Participants were grouped into two groups according to their maturity status, estimated as years from peak height velocity. Associations were determined with linear and nonlinear quadratic regression models. RESULTS: The nonlinear quadratic regression coefficient was significant for the 20-m dash among girls of both maturity status levels, and in maturity status level 1 boys; for the standing long jump among boys of both maturity status levels, and in maturity status level 1 girls. The Yo-Yo test was only significant for maturity status level 1 boys. For the medicine ball throw, the linear regression coefficient was significant for both maturity status levels in both sexes. Almost all physical fitness items were observed to have meaningfully large nonlinear relationships with BMIz, but they were not all significant due to the small sample size, especially in maturity status level 2. CONCLUSION: The association between BMI and physical fitness is nonlinear in the majority of its components, and those with lower and higher BMI had poorer fitness.