Blood glucose threshold and the metabolic responses to incremental exercise tests with and without prior lactic acidosis induction

Abstract

This study compared the metabolic-ventilatory responses and the glycemic threshold identified during lactate minimum (LM) and individual anaerobic threshold (IAT) tests. In addition, the ability to determine the anaerobic power, aerobic-anaerobic transition (Trans) (e.g. ventilatory threshold; VT) and the maximal oxygen consumption (VO(2max)) all within a single incremental treadmill test (IT) was investigated. Fifteen physically fit men [25.9 (5.5) years; 77.4 (6.5) kg] performed the following: test 1, IT for IAT; and test 2, LM: 30-s Wingate test followed by 8 min rest and then an IT that was the same as test 1. Blood lactate concentration [lac], glucose concentration [gluc], pH, PO(2), PCO(2), base excess (BE) and ventilatory variables were measured. At the beginning of the IT for LM, the ventilation, PO(2) and VO(2) were higher and the pH, BE and PCO(2) were lower in relation to IAT ( P<0.05), while no differences were observed after reaching LM intensity during IT. Moreover, the Trans could be identified by [lac] (IAT, LM), minute ventilation [V(E;) VT identified during IAT protocol (VT-IAT) and VT identified during LM protocol (VT-LM)], and [gluc] (IGT, GM) during the IT for IAT and LM. The velocities (kilometers per hour) corresponding to IAT (12.6+/-1.6), VT-IAT (12.5+/-1.7), IGT (12.6+/-1.6), LM (12.5+/-1.5), VT-LM (12.3+/-1.5), and GM (12.6+/-1.9) were not different from each other and the LM and IAT protocols resulted in the similar VO(2max). We concluded that: (1) after reaching the LM the metabolic responses during IT are similar to IAT; (2) performing a Wingate test prior to an IT does not interfere with the Trans and VO(2max) attainment; (3) and the IGT and GM can predict the Trans.

Métodos para identificar o limiar anaeróbio em indivíduos com diabete tipo 2 e em indivíduos não-diabéticos

“…The IGT seems to demarcate an exercise intensity above which blood glucose output overcomes its uptake and it is not different from the VT and LT identified in young health individuals 2 . Type 2 diabetes has been associated to skeletal muscle lipid accumulation, which inhibits insulin signaling and thus decreases GLUT-4 translocation, resulting in hyperglycemia 18 .…”

“…Also, the mean blood lactate and glucose, pH, BE, pO 2 and pCO 2 at rest and during the incremental test are presented in Figure 4 (A-D) (Figures 3 and 4). In spite of the differences between groups as presented in Tables 1 and 2, no differences were observed within groups for the workload, oxygen consumption and heart rate as related to the LT, VT, IGT, VT VE/W , LTv [lac]/W (p>0.05).…”

“…The anaerobic threshold (AT) reflects an exercise intensity above which an over-proportional increase in glycolysis rate, blood lactate ([lac]) and ventilation (VE) is observed paralleled to the pH diminution 1,2 .…”

The Effects of Chronic Aerobic and Anaerobic Exercise on Blood Nitric Oxide Levels

“…23 In accordance with the protocol, the subjects underwent 3 acute exercise-loading phases during the LMS test. 24 The first phase was a supramaximal Wingate cycle exercise test. Following the exercise phases, the subjects had 5-min passive resting periods.…”

Relações cineantropométricas e fisiológicas durante exercício incremental em esteira rolante

“…Diversos estudos relatam a utilização de índices como o limiar aeróbio, limiar anaeróbio e limiar ventilatório, os quais são amplamente utilizados para determinar intensidades para a aplicação de protocolos de treinamento (1,3) . Durante um teste incremental, há aumento da concentração de glicose saguínea ([GLI]) (4) , juntamente com o acúmulo de metabólitos (íons H + , entre outros). Entre estes, a concentração de lactato sanguíneo ([LAC]) é amplamente utilizada para determinar a demanda metabólica ao longo do teste (5) .…”