Bioenergetics and neuromuscular determinants of the time to exhaustion at velocity corresponding to (V) over dotO(2)max in recreational long-distance runners

Bertuzzi, R, Bueno, S, Pasqua, LA, Acquesta, FM, Batista, MB, Roschel, H, Kiss, MAPDM, Serrao, JC, Tricoli, V, and Ugrinowitsch, C. Bioenergetics and neuromuscular determinants of the time to exhaustion at velocity corresponding to (V) over dotO(2)max in recreational long-distance runners. J Strength Cond Res 26(8): 2096-2102, 2012-The purpose of this study was to investigate the main bioenergetics and neuromuscular determinants of the time to exhaustion (T-lim) at the velocity corresponding to maximal oxygen uptake in recreational long-distance runners. Twenty runners performed the following tests on 5 different days: (a) maximal incremental treadmill test, (b) 2 submaximal tests to determine running economy and vertical stiffness, (c) exhaustive test to measured the T-lim, (d) maximum dynamic strength test, and (e) muscle power production test. Aerobic and anaerobic energy contributions during the T-lim test were also estimated. The stepwise multiple regression method selected 3 independent variables to explain T-lim variance. Total energy production explained 84.1% of the shared variance (p = 0.001), whereas peak oxygen uptake ((V) over dotO(2)peak) measured during T-lim and lower limb muscle power ability accounted for the additional 10% of the shared variance (p = 0.014). These data suggest that the total energy production, (V) over dotO(2)peak, and lower limb muscle power ability are the main physiological and neuromuscular determinants of T-lim in recreational long-distance runners.

Effects of replica running shoes upon external forces and muscle activity during running

Twelve participants ran (9 km . h(-1)) to test two types of running shoes: replica and original shoes. Ground reaction force, plantar pressure and electromyographic activity were recorded. The shoes were tested randomly and on different days. Comparisons between the two experimental conditions were made by analysis of variance (ANOVA) test (P <= 0.05). The time to first peak, loading rate of the first peak and impulse of the first 75 ms of stance were significantly different between the shoes (P <= 0.05), revealing an increase of impact forces for the replica shoes. The peak plantar pressure values were significantly higher (P <= 0.05) when wearing replica shoes. During running, the contact area was significantly smaller (P <= 0.05) for the replica shoe. The electromyographic activity of the analysed muscles did not show changes between the two shoes in running. These findings suggest that the use of replica running shoes can increase the external load applied to the human body, but may not change the muscle activity pattern during locomotion. This new mechanical situation may increase the risk of injuries in these movements.

Predictors of the risk of falls among elderly with chronic atrial fibrillation

OBJECTIVES: Though elderly persons with chronic atrial fibrillation have more comorbidities that could limit indications for the chronic use of anticoagulants, few studies have focused on the risk of falls within this particular group. To evaluate the predictors of the risk of falls among elderly with chronic atrial fibrillation, a cross-sectional, observational study was performed. METHODS: From 295 consecutive patients aged 60 years or older with a history of atrial fibrillation who were enrolled within the last 2 years in the cardiogeriatrics outpatient clinic of the Instituto do Coracao do Hospital das Clinicas da Faculdade de Medicina da Universidade de Sao Paulo, 107 took part in this study. Their age was 77.9 +/- 6.4 years, and 62 were female. They were divided into two groups: a) no history of falls in the previous year and b) a history of one or more falls in the previous year. Data regarding the history of falls and social, demographic, anthropometric, and clinical information were collected. Multidimensional assessment instruments and questionnaires were applied. RESULTS: At least one fall was reported in 55 patients (51.4%). Among them, 27 (49.1%) presented recurrent falls, with body lesions in 90.4% and fractures in 9.1% of the cases. Multivariate logistic regression showed that self-reported difficulty maintaining balance, use of amiodarone, and diabetes were independent variables associated with the risk of falls, with a sensitivity of 92.9% and a specificity of 44.9%. CONCLUSION: In a group of elderly patients with chronic atrial fibrillation who were relatively independent and able to attend an outpatient clinic, the occurrence of falls with recurrence and clinical consequences was high. Difficulty maintaining balance, the use of amiodarone and a diagnosis of diabetes mellitus were independent predictors of the risk for falls. Thus, simple clinical data predicted falls better than objective functional tests.

Inflammatory and Immunological parameters in adults with Down syndrome

Abstract Background The increase in life expectancy within the general population has resulted in an increasing number of elderly adults, including patients with Down syndrome (DS), with a current life expectancy of about 50 years. We evaluate the parameters of humoral and cellular immune response, the quantitative expression of the regulator of calcineurin1 gene (RCAN1) and the production of cytokines. The study group consisted of adults DS (n = 24) and a control group with intellectual disability without Down syndrome (ID) (n = 21) and living in a similar environmental background. It was evaluated serology, immunophenotyping, the quantitative gene expression of RCAN1 and the production of cytokines. Results In the DS group, the results showed an increase in NK cells, CD8, decreased CD19 (p < 0.05) and an increase spontaneous production of IFNgamma, TNFalpha and IL-10 (p < 0.05). There was not any difference in RCAN1 gene expression between the groups. Conclusions These data suggest a similar humoral response in the two groups. The immunophenotyping suggests sign of premature aging of the immune system and the cytokine production show a proinflammatory profile.

Reprodutibilidade da curva força-tempo do estilo "Crawl" em protocolo de curta duração

O objetivo deste estudo foi analisar a reprodutibilidade dos parâmetros biomecânicos da curva força-tempo do estilo "Crawl" em um protocolo de 10 s no nado atado. Dezesseis nadadores do sexo masculino (idade: 20,4 ± 4,0 anos; tempo na prova de 100 m livre: 53,68 ± 0,99 s) realizaram dois esforços máximos de 10 s no nado atado. Os parâmetros força pico, força média, taxa de desenvolvimento de força, impulso, duração da braçada, tempo para atingir a força pico e força mínima foram representados pela média de oito braçadas consecutivas obtidas em cada tentativa. Utilizou-se o teste t para observar as diferenças entre os esforços para cada parâmetro. O nível de significância estabelecido foi de 5%. A reprodutibilidade relativa foi medida pelo coeficiente de correlação de Pearson e a consistência entre as duas tentativas pelo coeficiente de correlação intraclasse (CCI). A reprodutibilidade absoluta foi verificada pelo coeficiente de variação (CV). Não foi demonstrada diferença estatisticamente significante para nenhum parâmetro biomecânico quando comparados os dois esforços. Os elevados CCI e baixos CV indicaram alta consistência interna dos parâmetros analisados. Conclui-se que os parâmetros biomecânicos analisados a partir do nado atado são reprodutíveis quando empregado protocolo de curta duração o que demonstra a possibilidade de utilização do protocolo com alto grau de confiabilidade, por parte de treinadores e atletas.

Contribuição dos parâmetros biomecânicos para o desempenho de saltos verticais de jogadoras de basquetebol

O objetivo do presente estudo foi investigar a contribuição dos parâmetros biomecânicos para o desempenho do salto vertical com contramovimento (SV) e SV precedido de corrida (SVcorrida) em 19 jogadoras da seleção brasileira adulta de basquetebol feminino (26,2 ± 4,7 anos; 1,81 ± 0,07 m; 75,6 ± 12,6 kg; 20,4 ± 6,0% de gordura). Foram considerados os picos de força passiva (PFPa) e propulsão (PFP), tempo para alcance dos picos de força passiva (TPFPa) e propulsão (TPFP), "load rate" (LR), taxa de desenvolvimento de força (TDF), tempo de fase excêntrica (Texc) e concêntrica (Tcon). A análise de componentes principais revelou que 50,86% da altura de SV foi explicada por PFPa, TPFPa, LR, Texc e TPFP, e que 43,28% de SVcorrida foi explicada por PFPa, TPFPa, LR, PFP. Esses resultados sugerem que parâmetros temporais parecem contribuir de maneira mais significativa para o desempenho de salto, porém diferentes tipos de salto podem demandar comportamentos distintos de parâmetros biomecânicos.