Differences in physical activity levels of school domains between high- and low-active adolescents

To compare high active (HA) and low active (LA) adolescent's physical activity (PA) levels in three different domains: commuting to school, physical education (PE) class and recess time at school. Method: This is a cross-sectional study, with a quantitative approach and random sample of 176 (105 girls) adolescents aged 14 - 18 years old from 10 urban public high schools in southern from Brazil. PA levels were measured using a pedometer. The average number of steps was recorded on the way to school, during PE classes and during school recess time. Participants were classified as HA and LA according to Tudor-Locke's cut-off points. Data were analyzed using descriptive statistics and One-Way ANOVA stratified by sex. Results: Data showed differences of mean values between school commuting PA for girls (LA: 1057.60; HA: 1624.54; Δ: 566.94; p<0.001), during PE class (LA: 1401.75, HA: 1701.10; Δ: 308.53; p<0.05) and in recess time (LA: 443.09, HA: 611.98; Δ: 168.89; p=0.001), whereas for boys, differences only found between the mean values of PA during PE class (LA: 1787.91, HA: 2511.20; Δ: 723.29; p<0.01). Conclusion: HA girls are consistently more active in each domain analyzed compared to LA counterparts, while for boys PE class was the domain that differentiated the HA vs. LA adolescents. This study highlights some potential settings to be included in the policies focused in enhance PA levels among adolescents namely in the context of school PE.(AU)

Diferenças no arremesso de jogadores de basquete em cadeira de rodas e convencional / Differences of free-throw shot in wheelchair basketball and conventional players

O basquete em cadeira de rodas (BCR) segue praticamente as mesmas regras do basquete convencional (BC). Objetivo: Avaliar a ativação eletromiográfica dos músculos peitoral maior (PM), deltóide anterior (DA) e tríceps braquial (TB) durante o arremesso em atletas de BC e BCR. Método: Estudo transversal, no qual onze sujeitos foram submetidos a uma avaliação eletromiográfica dos músculos PM, DA, TB no membro que realiza o arremesso. Foi utilizado um eletromiógrafo de 4 canais (Miotec/Brasil) (2000Hz/canal). Resultados: Na comparação entre os músculos, o grupo BC mostrou diferença significativa, sendo observada maior ativação do músculo DA em relação aos demais, já no grupo BCR, não houve diferença. Na comparação entre os grupos, o músculo PM mostrou maior ativação no grupo BCR, enquanto o músculo DA estava mais ativo no grupo BC. O músculo TB não apresentou diferença significativa entre os grupos. Conclusão: A partir dos resultados do presente estudo os atletas dos grupos BC e BCR apresentaram diferenças na ativação elétrica durante o movimento do arremesso. Entretanto ambos os grupos ativaram mais o DA, seguido do TB e o músculo menos ativado foi o PM, sendo estas diferenças mais visíveis no grupo BC.

Wheelchair Basketball (WB) follows almost the same rules as Conventional Basketball (CB). Objective: Evaluate the electromyographic (EMG) activation of the pectoralis major (PM), anterior deltoid (AD), and triceps brachii (TB) muscles during shooting in CB and WB athletes and to verify whether there is any difference in muscle activation between the categories. Method: Comparing two groups in a transversal study, CB and WB, in which eleven individuals submitted to an electromyographic examination, of muscles PM, AD, TB on the extremity that was doing the shooting. We used a 4-channel EMG (Miotec/Brazil) (2000Hz/channel). Results: Comparing the muscles, the CB group showed a significant difference: greater AD muscle activation compared to the others; however in the WB group, no differences were found. When comparing between the groups, the PM muscle showed greater activation in the WB group, while the AD muscle was more active in the CB group. The TB muscle showed no difference between groups. Conclusion: From these results, the athletes from the CB and WB groups showed differences in muscle activation during shooting. However, both groups activated the AD the most, followed by the TB. The least active muscle was the PM, and these differences were more visible in the CB group.

A Proteína S100B e o exercício físico / Protein S100B and physical exercise

A proteína S100B cerebral tem sido utilizada como um marcador periférico de injúrias do sistema nervoso central (SNC). Entretanto, estudos recentes demonstraram que a S100B também aumenta após o exercício físico, embora o significado desse aumento ainda não esteja bem claro. Apesar de ser liberada, principalmente, por astrócitos, no sistema nervoso central, fontes de produção extracerebral de S100B durante o exercício podem estar implicadas no aumento sérico desta proteína. No entanto, exercícios que implicam impacto ao cérebro como o boxe, por exemplo, o aumento é claramente associado à lesão cerebral. Assim, trabalhos propõem que o aumento da S100B após o exercício estaria relacionado à secreção ativa por adipócitos e músculos lesados. Uma vez que a liberação da S100B pelo músculo lesado seja confirmada experimentalmente, o uso desta proteína poderia ser aprofundado,principalmente, no treinamento esportivo. Atualmente, estamos desenvolvendo protocolos na direção de avaliar o potencial valor da S100B como indicador de lesão do músculo esquelético. Portanto, o objetivo da presente revisão é apresentar o atual estado de conhecimento sobre a relação entre a proteína S100B e o exercício físico, discutindo os possíveis mecanismos envolvidos e propondo novas abordagens.

Protein S100B has been used as a peripheral biochemical marker of brain injury and/or activity. However, recent studies have demonstrated that this protein is also increased in serum after physical exercise, although the interpretation of this finding remains controversial. Although predominantly released by astrocytes in the central nervous system, extracerebral sources of protein S100B have been suggested to contribute to the increase in serum levels of this protein. However, in the case of exercises that have an impact on the brain such as boxing, elevated levels are clearly associated with brain damage. More recently, some studies have proposedthat protein S100B might be released by activated adipocytes and by damaged muscle cells. If confirmed experimentally, protein S100B might be potentially useful in sports training. We are currently investigating the potential role of serum protein S100B as an indicator of muscle damage. Therefore, the objective of this review was to discuss the current knowledge about the relationship between physical exercise and serum protein S100B and its possible leakage from muscle cells injured by exercise.