Exercise training in the aerobic/anaerobic metabolic transition prevents glucose intolerance in alloxan-treated rats

Background: Ninety percent of cases of diabetes are of the slowly evolving non-insulin-dependent type, or Type 2 diabetes. Lack of exercise is regarded as one of the main causes of this disorder. In this study we analyzed the effects of physical exercise on glucose homeostasis in adult rats with type 2 diabetes induced by a neonatal injection of alloxan. Methods: Female Wistar rats aged 6 days were injected with either 250 mg/ kg of body weight of alloxan or citrate buffer 0.01 M (controls). After weaning, half of the animals in each group were subjected to physical training adjusted to meet the aerobic-anaerobic metabolic transition by swimming 1 h/day for 5 days a week with weight overloads. The necessary overload used was set and periodically readjusted for each rat through effort tests based on the maximal lactate steady state procedure. When aged 28, 60, 90, and 120 days, the rats underwent glucose tolerance tests (GTT) and their peripheral insulin sensitivity was evaluated using the HOMA index. Results: The area under the serum glucose curve obtained through GTT was always higher in alloxan-treated animals than in controls. A decrease in this area was observed in trained alloxan-treated rats at 90 and 120 days old compared with non-trained animals. At 90 days old the trained controls showed lower HOMA indices than the non-trained controls. Conclusion: Neonatal administration of alloxan induced a persistent glucose intolerance in all injected rats, which was successfully counteracted by physical training in the aerobic/anaerobic metabolic transition. © 2008 Mota et al; licensee BioMed Central Ltd.

Determination of critical velocity and anaerobic capacity of running rats

The aim of this study was to validate a non-invasive protocol to determine aerobic and anaerobic capacity of treadmill running rats. Thirteen male Wistar rats (90 days old) were submitted to 4 exercise tests, consisting of running at 25, 30, 35 and 40 m min-1, continuously until exhaustion. For the critical velocity (CV) and anaerobic running capacity (ARC) estimations, the hyperbolic curve (velocity versus time to exhaustion (tlim)) was linearized to V= CV+ARC/tlim, where the CV and ARC were linear and slope coefficients, respectively. In order to verify if the CV was the maximal aerobic intensity, the rats were submitted to the maximal lactate steady state test (MLSS) composed of three 25-minute tests of continuous running trials at 15, 20 and 25 m min-1, with blood collection every 5 minutes. The CV was obtained at 22.8±0.7 m min-1 and the ARC, at 26.80±2.77 m. The MLSS was observed at 20m min-1, with blood lactate 3.84 ± 0.31 mmol L-1. There was a progressive increase in lactate concentration at 25 m min-1. The CV and MLSS were different, but presented a high and significant correlation (r=0.81). These results indicate that the non-invasive protocol can be used for physical evaluation of aerobic running rats, but the ARC should still be further investigated.

A mixed-integer LP model for the optimal allocation of voltage regulators and capacitors in radial distribution systems

This paper presents a mixed-integer linear programming model to solve the problem of allocating voltage regulators and fixed or switched capacitors (VRCs) in radial distribution systems. The use of a mixed-integer linear model guarantees convergence to optimality using existing optimization software. In the proposed model, the steady-state operation of the radial distribution system is modeled through linear expressions. The results of one test system and one real distribution system are presented in order to show the accuracy as well as the efficiency of the proposed solution technique. An heuristic to obtain the Pareto front for the multiobjective VRCs allocation problem is also presented. © 2012 Elsevier Ltd. All rights reserved.

How narrow is the spectrum of submaximal speeds in swimming?

The purpose of this study was to identify the boundary of submaximal speed zones (i.e., exercise intensity domains) between maximal aerobic speed (S-400) and lactate threshold (LT) in swimming. A 400-m all-out test, a 7 × 200 m incremental step test, and two to four 30-minute submaximal tests were performed by 12 male endurance swimmers (age = 24.5 ± 9.6 years; body mass = 71.3 ± 9.8 kg) to determine S-400, speed corresponding to LT, and maximal lactate steady state (MLSS). S-400 was 1.30 ± 0.09 m·s -1 (400 m-5:08 minutes:seconds). The speed at LT (1.08 ± 0.02 m·s-1; 83.1 ± 2.2 %S-400) was lower than the speed at MLSS (1.14 ± 0.02 m·s-1; 87.5 ± 1.9 %S-400). Maximal lactate steady state occurred at 26 ± 10% of the difference between the speed at LT and S-400. Mean blood lactate values at the speeds corresponding to LT and MLSS were 2.45 ± 1.13 mmol·L-1 and 4.30 ± 1.32 mmol·L-1, respectively. The present findings demonstrate that the range of intensity zones between LT and MLSS (i.e., heavy domain) and between MLSS and S-400 (i.e., severe domain) are very narrow in swimming with LT occurring at 83% S-400 in trained swimmers. Precision and sensitivity of the measurement of aerobic indexes (i.e., LT and MLSS) should be considered when conducting exercise training and testing in swimming. © 2013 National Strength and Conditioning Association.

Assessment of branch outage contingencies using the continuation method

This paper provides a contribution to the contingency analysis of electric power systems under steady state conditions. An alternative methodology is presented for static contingency analyses that only use continuation methods and thus provides an accurate determination of the loading margin. Rather than starting from the base case operating point, the proposed continuation power flow obtains the post-contingency loading margins starting from the maximum loading and using a bus voltage magnitude as a parameter. The branch selected for the contingency evaluation is parameterised using a scaling factor, which allows its gradual removal and assures the continuation power flow convergence for the cases where the method would diverge for the complete transmission line or transformer removal. The applicability and effectiveness of the proposed methodology have been investigated on IEEE test systems (14, 57 and 118 buses) and compared with the continuation power flow, which obtains the post-contingency loading margin starting from the base case solution. In general, for most of the analysed contingencies, few iterations are necessary to determine the post-contingency maximum loading point. Thus, a significant reduction in the global number of iterations is achieved. Therefore, the proposed methodology can be used as an alternative technique to verify and even to obtain the list of critical contingencies supplied by the electric power systems security analysis function. © 2013 Elsevier Ltd. All rights reserved.

Alocação ótima de reguladores de tensão em sistemas de distribuição de energia elétrica radiais usando uma formulação linear inteira mista. -

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Validação do glicosímetro portátil para avaliação, prescrição e monitoramento do treinamento aeróbio

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Respostas fisiológicas durante o exercício intervalado realizado no ciclismo com recuperação passiva e ativa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Respostas metabólicas e da técnica de nado durante o exercício realizado na velocidade correspondente à máxima fase estável de lactato sanguíneo determinada de forma contínua e intermitente

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estresse oxidativo em ratos exercitados em diferentes intensidades

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Predição da intensidade de corrida em máxima fase estável de lactato a partir da velocidade de crítica em atletas fundistas de alto rendimento: relações com performances

Pós-graduação em Ciências da Motricidade - IBRC

Validade do modelo distância-tempo para a determinação das capacidades aeróbia e anaeróbia em jogadores de futebol

Pós-graduação em Ciências da Motricidade - IBRC

Análise de parâmetros de força e padrão de nado de ratos controles e obesos, a partir de um sistema de aquisição de sinais em natação atada: Influência da intensidade do exercício e da densidade corporal

Pós-graduação em Ciências da Motricidade - IBRC

Desenvolvimento e teste de um programa computacional para simulação de plantas térmicas e de potência

Pós-graduação em Engenharia Mecânica - FEIS

Comparação de diferentes métodos lactacidêmicos e glicêmicos de determinação do limiar anaeróbio em eqüinos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)