Efeito da baixa disponibilidade de carboidrato na dieta sobre o primeiro limiar de variabilidade da frequência cardíaca em teste progressivo em cicloergomêtro

Abstract

The aim of the present study was to analyze the effect of a low carbohydrate (CHO) diet on the first physiological transition threshold (TT1) indentified by using analysis of the behavior of Heart Rate Variability (HRV) in progressive test on cycle ergometer. Nine subjects of 18 to 32 years underwent two cycle ergometer tests with initial load of 25W and increments of 25W every two minutes. The test was over when the individual could not follow the determined rotation (60 to 70 rpm) or for voluntary exhaustion. The subjects underwent the tests with an interval of one week in two different dietetic situations (isocaloric diets) consumed in a period of 72 hours prior to testing Normal Diet (ND) and Hypoglicidic Diet (HD). The following variables were measured: HRV at each stage to identify HRV threshold (HRVT) and blood lactate [La] concentrations to identify the first lactate threshold (LT1). The analyzed variables were load and Heart Rate in HRVT and LT1. Higher values were found for LT1 and HRVT when expressed by relative loads in HD. These results suggest that LT1 and HRVT can be modified by manipulating CHO levels in a diet.