Determinação do limiar anaeróbio pela carga crítica superestima teste de lactato mínimo / Determination the anaerobic threshold for critical workload overestimates lactate minimum test

Introdução: A utilização de métodos específicos de mensuração é de fundamental importância para a identificação da capacidade aeróbia e prescrição da intensidade de exercício. Normalmente esta definição é feita pela determinação do limiar anaeróbio (Lan) que corresponde à máxima fase estável entre produção e remoção de lactato sanguíneo (MFEL). Dentre as mais variadas formas de se det ermin ar a MFEL estão os testes de lactato mínimo (LM) e carga crítica (CC). No entanto, não se sabe se a utilização dessas formas de avaliação pode acarretar em resultados distintos. Objetivo: O objetivo do presente estudo foi comparar os valores de Lan obtidos por meio dos testes de CC e de LM em rat o s W istar. Método : Foram utilizados 32 ratos machos (Wistar), com peso médio 411,0 (± 4 0 ,7 gramas), o s quais fo ram submetidos às baterias de testes de CC e de LM. O teste de LM foi realizado com a indução à hiperlactacidemia com dois estímulos correspondentes a 13% do peso corporal (PC), seguido de intervalo passivo de nove minutos e teste incremental composto por estágios com duração de cin co m inut os e cargas equivalentes a 4.0, 4.5, 5.0, 5.5, 6.0 e 7.0 % do PC. Já a CC foi obtida p o r m eio da in dução ao exercício em quatro diferentes estímulos randomizados, com cargas correspondentes a 7, 9, 11 e 1 3 % do PC. Resultados: Os resultados demonstraram que o Lan médio determinado pelo Teste de CC foi de 5,8 ± 1,2% do peso corporal (PC) e 4,9 ± 0,6% do PC determinado pelo Teste de LM. Co nclusão: P ode ­ se concluir que o limiar anaeróbio determinado por meio do teste CC superestimou em 18,4% o valor obtido por meio do teste de LM...(AU)

Introduction: The utilization of specific measurement methods is of fundamental importance for the identification of aerobic capacity and prescription of exercise. This determination is usually m ade through measurement of the anaerobic threshold (Lan) which corresponds to the maximal lactate st eady state (MLSS). Among the more varied forms of determination of MLSS are the minimum lactate (LM) and critical overload tests (CC). However, it is not known if the utilization of these forms o f ev aluatio n can lead to different results. Objective: The aim of this study was to compare the Lan v alues o btained through the CCand LM tests in Wistar rats. Method: For this purpose, 32 male Wistar rats were used, with an average weight of 411.0 ± 40.7 grams, submitted to CC and LM tests. The LM test was performed fo r the induction of a hyperlactacidemia with two stimuli corresponding to 13% of body weight (BW), followed by a passive interval of nine minutes and an incremental test composed of stages with a duratio n of five minutes and loads equivalent to 4.0, 4.5, 5.0, 5.5, 6.0, and 7.0% of BW . T he CC was o bt ain ed through induced exercise in four randomized stimuli, with loads corresponding to 7, 9 , 1 1, and 1 3 % o f BW. Results: It was observed that the mean anaerobic threshold determined by CC was 5.8 ± 1 .2 % BW , and determined by LM was 4.9 ± 0.6% BW. Conclusion: It is concluded that th e an aero bic th resho ld determined through the critical workload test overestimates the value obtained through the lactate minimum test by 18.4%, thus impeding its use as an aerobic training intensity predictor in Wistar rats. Keywords: Lactic acid, Critical load, Anaerobic threshold, Wistar rats...(AU)

Non-exhaustive test for aerobic capacity determination in running rats.

A simple and applicable method for non-exhaustive aerobic evaluation in running rats is described. Wistar rats were submitted to running test at different velocities (10, 15, 20, 25 m/min) with 48 h recovery among them. At each velocity, the rats ran two bouts of 5 min with 2 min of rest between bouts. Blood samples were collected at the end of each bout for lactate determination. For each intensity, delta lactate was calculated and using deltas obtained by four tests, an individual linear interpolation was plotted. The y-intercept of linear interpolation was the “null delta lactate” equivalent to the critical velocity (CV). To verify the lactate stabilization at CV, the animals were submitted to 25 min of continuous exercise (15, 20, 25 m/min), with blood collection every 5 min. The estimated CV was 16.6±0.7 m/min, with significant linear regressions (R=0.90±0.03). The rats presented maximal lactate steady state (MLSS) at 3.9±0.4 mmol/L, at 20 m/min. The CV was less than MLSS but significantly correlated with this parameter (r=0.78). This non-exhaustive test seems to be valid for the aerobic evaluation of sedentary rats and this protocol underestimates the MLSS in 20%. This test seems to be the interesting method for the evaluation of rats submitted to acute exercise or physical training.