Glucose kinetics and substrate oxidation during exercise in the follicular and luteal phases

Ted W. Zderic, Andrew R. Coggan, Brent C. Ruby

Research output: Contribution to journalArticlepeer-review

148 Scopus citations

Abstract

The purpose of this investigation was to determine whether plasma glucose kinetics and substrate oxidation during exercise are dependent on the phase of the menstrual cycle. Once during the follicular (F) and luteal (L) phases, moderately trained subjects [peak O2 uptake (V̇o2) = 48.2 ± 1.1 ml·min-1·kg-1; n = 6] cycled for 25 min at ∼70% of the V̇o2 at their respective lactate threshold (70%LT), followed immediately by 25 min at 90%LT. Rates of plasma glucose appearance (Ra) and disappearance (Rd) were determined with a primed constant infusion of [6,6-2H]glucose, and total carbohydrate (CHO) and fat oxidation were determined with indirect calorimetry. At rest and during exercise at 70%LT, there were no differences in glucose Ra or Rd between phases. CHO and fat oxidation were not different between phases at 70%LT. At 90%LT, glucose Ra (28.8 ± 4.8 vs. 33.7 ± 4.5 μmol·min-1·kg-1; P < 0.05) and Rd (28.4 ± 4.8 vs. 34.0 ± 4.1 μmol·min-1·kg-1; P < 0.05) were lower during the L phase. In addition, at 90%LT, CHO oxidation was lower during the L compared with the F phase (82.0 ± 12.3 vs. 93.8 ± 9.7 μmol·min-1·kg-1; P < 0.05). Conversely, total fat oxidation was greater during the L phase at 90%LT (7.46 ± 1.01 vs. 6.05 ± 0.89 μmol·min-1·kg-1; P < 0.05). Plasma lactate concentration was also lower during the L phase at 90%LT concentrations (2.48 ± 0.41 vs. 3.08 ± 0.39 mmol/1; P < 0.05). The lower CHO utilization during the L phase was associated with an elevated resting estradiol (P < 0.05). These results indicate that plasma glucose kinetics and CHO oxidation during moderate-intensity exercise are lower during the L compared with the F phase in women. These differences may have been due to differences in circulating estradiol.

Original languageEnglish
Pages (from-to)447-453
Number of pages7
JournalJournal of Applied Physiology
Volume90
Issue number2
DOIs
StatePublished - 2001

Keywords

  • Carbohydrate oxidation
  • Estradiol
  • Fat oxidation
  • Lactate threshold

Fingerprint

Dive into the research topics of 'Glucose kinetics and substrate oxidation during exercise in the follicular and luteal phases'. Together they form a unique fingerprint.

Cite this