Efeitos da atividade física sobre densidade mineral óssea de mulheres saudáveis na pré-menopausa

Study Design: Sistematic review of literature.Aims: Physical activity is an important stimulus to increase bone mineral density (BMD). Whereby the resistance of the bone is associated with BMD, microstructure and material properties, improvements in bone mass are important to prevent osteoporosis in old ages. Despite many studies on the subject, there is no consensus on what is the best type of exercise, intensity and frequency for improvements in osteogenesis and promotion of BMD gain. This study aimed to investigate the types of physical activities that results in better osteogenic effects on increasing BMD in healthy premenopausal women.Methodology: We searched scientific articles in Pubmed and Science Direct databases published in the last ten years. We selected controlled studies which used high-impact activities or resistance training. We used systematic analysis of the selected articles.Results: Fifteen articles were included in this review, which were separated into two groups according to the type of exercise. We performed a comparative analysis of the methods used and the results achieved. There were more efficient protocols using high impact exercise even if it was a short-term program resulting in increased BMD in the proximal femur (femoral neck and intertrochanteric region).Conclusion: There were fewer studies observing increases in BMD at the lumbar spine when resistance exercise with load or high impact loads were used. Most experimental protocols performed in relatively short-term programs (6 months) demonstrated that exercise programs that were simple, easy to perform, and not using special devices are sufficient to promote bone remodeling at specific sites resulting in increased BMD.in increased BMD.Modelo de estudo: Revisão sistemática da literatura.Objetivo: A atividade física representa um importante estímulo ao aumento da densidade mineral óssea (DMO). Como a resistência dos ossos está associada tanto a DMO, quanto a microestrutura e propriedades do material, melhorias na massa óssea são importantes na prevenção de osteoporose na idade mais avançada. Apesar de muitos estudos sobre o tema, não existe consenso sobre qual seria o melhor tipo de atividade física, intensidade e frequência para melhorias na osteogênese e promoção do ganho de DMO. O objetivo deste estudo foi investigar os tipos de atividades físicas com melhor efeito osteogênico de aumento da DMO em mulheres saudáveis na pré-menopausa.Metodologia: Realizou-se levantamento bibliográfico de artigos científicos nas bases de dados Pubmed e Direct Science publicados nos últimos dez anos. Foram selecionados estudos controlados com exercícios de alto impacto e resistido. Utilizou-se análise sistematizada dos artigos selecionados.Resultados: Foram incluídos 15 artigos nesta revisão, os quais foram separados em dois grupos, conforme o tipo de exercício. Foi realizada análise comparativa de metodologias utilizadas e resultados alcançados. Constatou-se maior eficiência do protocolo de exercício de alto impacto, mesmo em curtoperíodo de execução para aumento da DMO do fêmur proximal (colo femoral e região intertrocantérica). Em menor frequência, foi observado aumento da DMO na coluna lombar quando exercícios resistidos ou de impactos maiores foram usados.Conclusões: A maioria dos artigos executou protocolo experimental em período relativamente curto (6 meses), demonstrando que programas de exercícios simples, de fácil execução, curto período de aplicação e sem uso de aparelhos específicos são suficientes para promover remodelação óssea emsítios específicos com aumento da DMO

Yo-Yo IR2 test e teste de margaria: validade, confiabilidade e obtenção da frequência cardíaca máxima em jogadores jovens de futebol

Os objetivos do presente estudo foram: i) avaliar a validade de constructo do Yo-Yo Intermittente Recovery Test Level 2 (Yo-Yo IR2) e do teste de Margaria (TM) com o desempenho em alta intensidade de exercício durante jogos oficiais em jogadores de futebol; ii) verificar a confiabilidade (teste-reteste) dos dois testes; iii) comparar os valores da frequência cardíaca máxima (FCM) obtida nesses protocolos e em jogo. Dezoito jogadores (média ± DP; idade 14 ± 0,8 anos, estatura 172 ± 9cm, peso 64,3 ± 8,5kg) pertencentes à mesma equipe foram avaliados em teste-reteste nos referidos protocolos e no percentual de tempo de permanência acima de 85% da FCM individual (PTP>85%FCM) em dois jogos oficiais do Campeonato Mineiro Infantil. Uma alta correlação foi encontrada entre o desempenho no Yo-Yo IR2 e PTP>85%FCM (rs = 0,71; p 85%FCM (rs = 0,44; p = 0,06). O Yo-Yo IR2 se mostrou mais variável e menos reprodutível (CV = 11%; CCI [95% IC] = 0,38) do que TM (CV = 1%; CCI [95% IC] = 0,93). O maior valor de FCM (p < 0,001) ocorreu no jogo (202 ± 8bpm). A FCM no Yo-Yo IR2 (194 ± 4bpm) foi menor (p < 0,006) do que TM (197 ± 6bpm). Conclui-se que o Yo-Yo IR2 pode ser considerado mais válido para predizer a manutenção de alta intensidade de exercício em jogo que é uma importante medida de desempenho no futebol. Porém, há necessidade de padronização rigorosa entre os procedimentos de avaliação para estabilidade da medida. A FCM deve ser observada em diversas situações, principalmente competitiva, para possibilitar que ocorra o maior valor individual

The effects of a high dosage of creatine and caffeine supplementation on the lean body mass composition of rats submitted to vertical jumping training

<p>Abstract</p> <p>Background</p> <p>The influences of creatine and caffeine supplementation associated with power exercise on lean body mass (LBM) composition are not clear. The purpose of this research was to determine whether supplementation with high doses of creatine and caffeine, either solely or combined, affects the LBM composition of rats submitted to vertical jumping training.</p> <p>Methods</p> <p>Male Wistar rats were randomly divided into 8 groups: Sedentary (S) or Exercised (E) [placebo (Pl), creatine (Cr), caffeine (Caf) or creatine plus caffeine (CrCaf)]. The supplemented groups received creatine [load: 0.430 g/kg of body weight (BW) for 7 days; and maintenance: 0.143 g/kg of BW for 35 days], caffeine (15 mg/kg of BW for 42 days) or creatine plus caffeine. The exercised groups underwent a vertical jump training regime (load: 20 - 50% of BW, 4 sets of 10 jumps interspersed with 1 min resting intervals), 5 days/wk, for 6 weeks. LBM composition was evaluated by portions of water, protein and fat in the rat carcass. Data were submitted to ANOVA followed by the Tukey post hoc test and Student's <it>t </it>test.</p> <p>Results</p> <p>Exercised animals presented a lower carcass weight (10.9%; <it>P </it>= 0.01), as compared to sedentary animals. However, no effect of supplementation was observed on carcass weight (P > 0.05). There were no significant differences among the groups (P > 0.05) for percentage of water in the carcass. The percentage of fat in the group SCr was higher than in the groups SCaf and ECr (P < 0.05). A higher percentage of protein was observed in the groups EPl and ECaf when compared to the groups SPl and SCaf (P < 0.001). The percentage of fat in the carcass decreased (P < 0.001), while those of water and protein increased (P < 0.05) in exercised animals, compared to sedentary animals. Caffeine groups presented reduced percentage of fat when compared to creatine supplemented groups (P < 0.05).</p> <p>Conclusions</p> <p>High combined doses of creatine and caffeine does not affect the LBM composition of either sedentary or exercised rats, however, caffeine supplementation alone reduces the percentage of fat. Vertical jumping training increases the percentages of water and protein and reduces the fat percentage in rats.</p

Temperature control of hypertensive rats during moderate exercise in warm environment

The control of body temperature in Spontaneously Hypertensive Rat (SHR) subjected to exercise in warm environment was investigated. Male SHR and Wistar rats were submitted to moderate exercise in temperate (25°C) and warm (32°C) environments while body and tail skin temperatures, as well as oxygen consumption, were registered. Total time of exercise, workload performed, mechanical efficiency and heat storage were determined. SHR had increased heat production and body temperature at the end of exercise, reduced mechanical efficiency and increased heat storage (p < 0.05). Furthermore, these rats also showed a more intense and faster increase in body temperature during moderate exercise in the warm environment (p < 0.05). The lower mechanical efficiency seen in SHR was closely correlated with their higher body temperature at the point of fatigue in warm environment (p < 0.05). Our results indicate that SHR exhibit significant differences in body temperature control during moderate exercise in warm environment characterized by increased heat production and heat storage during moderate exercise in warm environment. The combination of these responses result in aggravated hyperthermia linked with lower mechanical efficiency