Fernando José de Sá Pereira Guimarães

Obesidade abdominal em adolescentes: prevalência e associação com atividade física e hábitos alimentares

BACKGROUND: Abdominal obesity in adolescents is associated with cardiovascular and metabolic diseases, but its prevalence and the factors associated with its occurrence are unknown. OBJECTIVES: To determine the prevalence of abdominal obesity in adolescents, and to evaluate whether the indicators of physical activity and dietary habits are associated with the occurrence of abdominal obesity in adolescents. METHODS: The sample included 4138 high school students (14-19 years), selected by cluster sampling in two stages. We obtained data using the Global School-based Health Survey, and anthropometric measurements were taken for determination of overweight and abdominal obesity. Logistic regression was used for analysis of behavioral factors associated with the occurrence of abdominal obesity. The identification of cases of abdominal obesity was performed by waist circumference analysis, using age- and gender-related cutoff points as reference. RESULTS: The mean age was 16.8 years (s = 1.4), and 59.8% of subjects were female. The prevalence of abdominal obesity was 6% (95%CI: 5.3-6.7), and it was significantly higher among girls (6.7%, 95%CI: 5.8-7.8) than among boys (4.9%, 95%CI: 3, 9-6, 0). In the crude analysis, gender and overweight were associated with the occurrence of abdominal obesity. The analysis adjustment by logisic regression allowed us to observe that physical activity was significantly associated with the occurrence of obesity in this group (OR = 0.7; 95% CI: 0.49-0.99), regardless of the presence of overweight. CONCLUSIONS: The prevalence of abdominal obesity was low compared to that observed in international studies, and physical activity was a factor associated with the occurrence of this event in adolescents.

Validation of an equation for estimating maximal oxygen consumption of nonexpert adult swimmers

Objective To validate an equation to estimate the maximal oxygen consumption (VO2max) of nonexpert adult swimmers. Methods Participants were 22 nonexpert swimmers, male, aged between 18 and 30 years (age: 23.1 ± 3:59 years; body mass: 73.6 ± 7:39 kg; height 176.6 ± 5.53 cm; and body fat percentage: 15.9% ± 4.39%), divided into two subgroups: G1 – eleven swimmers for the VO2max oximetry and modeling of the equation; and G2 – eleven swimmers for application of the equation modeled on G1 and verification of their validation. The test used was the adapted Progressive Swim Test, in which there occurs an increase in the intensity of the swim every two laps. For normality and homogeneity of data, Shapiro-Wilk and Levene tests were used, the descriptive values of the average and standard deviation. The statistical steps were: (1) reliability of the Progressive Swim Test – through the paired t-test, intraclass correlation coefficient (ICC), and the Pearson linear correlation (R) relative to the reproducibility, the coefficient of variation (CV), and standard error measurement (SEM) for the absolute reproducibility; (2) in the model equation to estimate VO2max, a relative VO2 was established, and a stepwise multiple regression model was performed with G1 – so the variables used were analysis of variance regression (AR), coefficient of determination (R2), adjusted coefficient of determination (R2a), standard error of estimate (SEE), and Durbin–Watson (DW); (3) validation of the equation – the results were presented in graphs, where direct (G1) and estimated (G2) VO2max were compared using independent t-test, linear regression (stressing the correlation between groups), and Bland–Altman (the bias agreement of the results). All considered a statistical significance level of P < 0.05. Results On the trustworthiness of the Progressive Swim Test adapted presented as high as observed (R and ICC > 0.80, CV < 10%, and SEM < 2%). In the equation model, VO2max has been considered the third model as recommended due to the values found (AR < 0.01, R = 0795, R2 = 0633; R2a = 0.624, SEE = 7.21, DW = 2.06). Upon validation of the equation, no significant differences occurred between G1 and G2 (P > 0.01), linear regression stressed a correlation between the groups (R > 0.80, P < 0.01), and Bland–Altman plotting of the results was within the correlation limits of 1.96 (95% confidence interval). Conclusion The estimating equation for VO2max for nonexpert swimmers is valid for its application through the Progressive Swim Test, providing to contribute in prescribing the swimming lessons as a method of evaluating the physical condition of its practitioners.

Avaliação antropométrica e de composição corporal de atletas paraolímpicos brasileiros

A number of studies featuring aspects related to the dimension, proportion, composition, and human maturation show very close relationships between forms and proportions and human movements1. It has also been shown that there is a clear relationship between some anthropometric human measurements and the risk of metabolic diseases2. Helmrich et al.3 have shown the relationship between the IMC (index of corporal mass) and the development of diabetes in men, and Manson et al.4 showed similar relationships for women. An anthropometric evaluation of Brazilian paralympic athletes was performed to identify the profile of different groups of athletes and define their status under the light of corporal formation. This study aimed at finding out new methods of optimizing athletic performance during the Sydney 2000 Paralympic Games. Some of the main parameters used to define diets and specific training were the measures of the body fat distribution, total number of cutaneous folds, IMC and RCQ. A number of alterations were detected when comparing those parameters with the different groups of athletes. These data can be used to create a data bank for future studies of anthropometric parameters of disable athletes.

Does the type of sedentary behaviors influence blood pressurein adolescents boys and girls? A cross-sectional study

The aim of this study was to analyze the association between different sedentary behaviors and high blood pressure in adolescent boys and girls. We conducted a cross-sectional study with 6,264 Brazilian adolescents (14 to 19 years old). Demographic data, obesity indicators and blood pressure, were evaluated. Time spent in the sedentary behaviors (television viewing, playing video games, using the computer, non-screen sitting and, total time sitting) were also assessed. The girls spent more time watching television than boys, whereas boys spent more time using computers and video games (12.7% vs. 7.4%, p < 0.001) than girls. Boys who watched more than four hours of television presented higher odds to give high blood pressure after adjustments for physical activity level, body mass index, age and educational level of mother (OR = 2.27, p < 0.001). In girls, we did not find a relation between sedentary behaviors and high blood pressure (p > 0.05). Television viewing time is associated with high blood pressure only boys. So, reduce this sedentary behavior, stimulating physical activities, might be essential to health, principally for male adolescents.

The Compact Wheelchair Roller Dynamometer

The equipment for evaluating the propulsion of a wheelchair is very complex and expensive. To validate a new dynamometer prototype for assessing the propulsion capacity of wheelchairs, 21 healthy subjects (age: 20.9±2.4 yr; weight: 68.9±7.9 kg; height: 174.0±7.1 cm; BMI: 22.7±2.5 kg·m −2 ) who do not normally require wheelchairs performed a sprint protocol for 20 s after a 1-min warm-up. The power and rotation data acquired by the prototype (both right and left sides) were compared with those of a reference system via high-speed videography (240 fps). The results showed high levels of accordance (95% CI), excellent values for the intraclass correlation coefficient (ICC: .99; P <0.00), no significant differences in the rotation ( P =0.91) and power ( P =0.94) between the methods. The proposed equipment met the validation criteria and thus can be applied as a new tool for assessing wheelchair propulsion.

Avaliação biomecânica de atletas paraolímpicos brasileiros

A biomecânica do esporte e uma disciplina cientifica da qual os movimentos desportivos sao descritos e explicados a luz de conceitos e metodos mecânicos1. De acordo com a area de aplicacao a biomecânica pode ser subdividida em biomecânica do rendimento, biomecânica antropometrica e biomecânica preventiva. A biomecânica do rendimento esta diretamente relacionada a analise da tecnica do movimento, cujas funcoes sao a identificacao e avaliacao das variaveis de influencia e o diagnostico individual em relacao as falhas tecnico-motoras registradas no movimento2. A biomecânica utiliza como metodos de medicao de seus parâmetros quantitativos a cinemetria, a eletromiografia, a dinamometria e a antropometria3,4. O objetivo desse trabalho foi fazer analises quantitativa e qualitativa de parâmetros biomecânicos de provas de atletismo e natacao, utilizando a cinemetria. Os resultados mostraram imperfeicoes na conducao da tecnica dos movimentos, em especial, das disciplinas de arremessos no atletismo e na natacao. Tais resultados serviram como subsidios para os treinadores adaptarem e modificarem seus treinamentos no sentido de corrigir tais imperfeicoes.