title: 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.
authors.affiliation: Catholic University of Brasília, Aguas Clams-DF, QS 07 Lote 1, Bloco G, sala 119, 72022-900, Brazil. hsimoes@pos.ucb.br
authors.forename: Herbert Gustavo
authors.initials: HG
authors.lastname: Simões
authors.forename: Carmen S G
authors.initials: CS
authors.lastname: Campbell
authors.forename: Michael R
authors.initials: MR
authors.lastname: Kushnick
authors.forename: Akiko
authors.initials: A
authors.lastname: Nakamura
authors.forename: Christos S
authors.initials: CS
authors.lastname: Katsanos
authors.forename: Vilmar
authors.initials: V
authors.lastname: Baldissera
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Moffatt
mesh_terms: D000140:Acidosis, Lactic / Q000378:metabolism*; D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology*; D005080:Exercise Test; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood; D008297:Male; D011659:Pulmonary Gas Exchange / Q000502:physiology
chemical_list: D001786:Blood Glucose; D019344:Lactic Acid