CARACTERIZAÇÃO DO TREINAMENTO FÍSICO EXPERIMENTAL DE ENDURANCE EM ESTEIRA ADAPTADA ATRAVÉS DE MARCADORES METABÓLICOS ENERGÉTICOS

Rats have been used, as an experimental model, in studies that evaluate the effects of exercise training in improving performance and in degenerative diseases behavior. Thus, standardization protocols that evaluates animal physical capacity is extremely important to get a reliable control of this variable. Increasing speed tests until exhaustion aims to identify the anaerobic threshold or lactate, an important indicator of ability to perform endurance exercises. The blood lactate maximum steady state also becomes an excellent performance indicator, representing the equalization of the maximum input capacity and blood lactate removal. This study aimed to characterize the method for measuring blood lactate in rats during increasing speed test and continuous speed test in order to identify the blood lactate maximal steady state for rats on adapted treadmill and analyze energy metabolic markers of physical training. Were initially used 20 animals, of which 12 rats were selected by the stress test (TST), exercised (n = 6) and sedentary (n = 6), aged 60 days. The animals underwent to the process of treadmill habituation and adaptation in the first two weeks till TE. The training prescription of 60% was based on exhaustive testing, initial speed of 0.3 km / h increase in speed (0.2 km / h) every 3 min for 6 weeks. At the end of training, exhaustive tests for analysis of total speed, distance traveled and total exhaustion time was, again, conducted. In progressive speeds tests, at rest and every three minutes, and in continuous velocities tests, at rest and every seven minutes, blood samples were collected (25μl) for lactate ratio analysis (Yellow Springs 1500) and (10 l) behavior of blood glucose analysis (glucometer Accu-chek Active) via the caudal artery during completion of efforts. It was detected the anaerobic threshold and maximum lactate steady state in the studied animals, the performance improvement as well the lactate metabolism of exercised animals. There was also expressive correlation with blood glucose and lactate in physical fitness improvement at increasing speed test. Higher levels of citrate synthase enzyme activity in skeletal muscle, heart and liver were detected. Higher glycogen content in trained animals skeletal muscles also were found. Indicating elevated oxidative fibers in exercised animals, was found an ATPase activity increased in muscle fiber type I. An elevated PGC-1α protein expression was detected, indicating mitochondrial biogenesis. Levels of PDK4, HKII, ACC and cytochrome C in rats skeletal muscle and liver were also elevated in the trained animals. Increased nitrite concentrations were also founded in the heart, indicating nitric oxide concentration in the exercised animal hearts. It was concluded that the training prescription up to 60% obtained from the exhaustive test without blood collection corresponds to the maximum lactate steady state, and therefore being a reliable method for aerobic or endurance exercise prescription. The standardization of assessment protocols was effective in assessing the anaerobic threshold and performance of training. The training intensity used was satisfactory in causing functional and structural adaptations, observed by enzyme activity elevation and energy metabolism proteins expression.