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Int J Sports Med 1981; 02(3): 139-142
DOI: 10.1055/s-2008-1034600
© Georg Thieme Verlag Stuttgart · New York

Alteration in the Lactate Threshold with Changes in Substrate Availability*

J. L. Ivy, D. L. Costill, P. J. Van Handel, D. A. Essig, R. W. Lower
  • Human Performance Laboratory Ball State University, Muncie, Indiana, USA
* This study was supported by NIH Grant (HL 20408-02).
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Publication History

Publication Date:
14 March 2008 (online)

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Abstract

The lactate threshold (LT) was studied (N = 9) during ergometer cycling under control (C), high blood glucose (G), and high blood free fatty acid (F) conditions. During the G trial blood lactate (HLa) was greater than C at all work loads (P < 0.05). Adjusted blood HLa values (HLa - pre-exercise value = Δ HLa), however, were essentially the same for the C and G trials. Determination of the LT disclosed that there was no difference between the two treatments (C = 53.9 ± 2.6% V̇O2max; G = 52.7 ± 3.1% V̇O2max). Elevation of blood FFA levels, however, reduced both the HLa and Δ HLa at all work loads from 150-250 W (P < 0.05) although V̇O2 was the same as C. In addition, a significant increase in the LT (F = 59.8 ± 2.6% V̇O2max) was found for the F treatment. These data suggest that (1) the LT can be altered by substrate availability and (2) that muscle tissue anoxia may not be solely responsible for lactate production during sub-maximal work.

Key words

anoxia - free fatty acid - glucose - respiratory exchange ratio - ventilation

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