Blood Glucose Threshold is Not Consistent with Blood Lactate Threshold by Different Evaluation Methods
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Objectives: We investigated the relationship between blood glucose and blood lactate kinetics during the incremental exercise and lactate minimum tests and examined the glucose threshold (GT) and lactate threshold (LT) values determined by different evaluation methods. Methods: Nine endurance runners participated in both tests. LT and GT were determined according to log-log method (GT-_<log> and LT-_<log>) in the incremental exercise test and by the lowest blood lactate and glucose in the lactate minimum test (Glucose minimum; GM and Lactate minimum; LM). Results: During the lactate minimum test, blood glucose was stable after the supramaximal exercise (Wingate test), whereas blood lactate increased significantly. Thus, blood lactate kinetics differed significantly between these tests whereas there was no difference in blood glucose kinetics between the tests. In comparison of the GT and LT, GT-_<log> and LT-_<log> were not significantly different (15.5 ± 1.0 km・h^<-1> vs. 15.1 ± 0.9 km・h^<-1>), and the correlation was significant (r = 0.720; p<0.05). The Bland-Altman plots revealed that mean bias of LT-_<log> and GT-_<log> (-0.33 km・h^<-1>) was not significantly different from 0. Therefore, consistent with previous study, GT-_<log> was close to LT-_<log>. In contrast, GM was significantly lower than LM (14.7 ± 0.6 km・h^<-1> vs. 15.3 ± 1.0 km・h^<-1>; p<0.05) during the lactate minimum test, but the correlation was significant (r = 0.693; p<0.05). The Bland-Altman plots also revealed that mean LM and GM bias (0.67 km・h^<-1>) was significantly different from 0 (p<0.05). Hence, GM was not consisted with LM, which was different from previous studies. Conclusions: Blood glucose and blood lactate kinetics were different between the two tests. Thus, GT was not consistent with LT by different evaluation methods, and GT might reflect a different physiological parameter than LT.
- Advances in exercise and sports physiology
Advances in exercise and sports physiology 21(1), 17-24, 2015-04
Japan Society of Exercise and Sports Physiology