Substrate oxidation is altered in women during exercise upon acute altitude exposure

Beth A. Beidleman, Paul B. Rock, Stephen R. Muza, Charles S. Fulco, Lindsay L. Gibson, Gary H. Kamimori, Allen Cymerman

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Purpose: The purpose of this study was to determine whether substrate oxidation during submaximal exercise in women is affected by an acute exposure to 4300-m altitude and menstrual cycle phase. Methods: Eight female lowlanders (mean ± SD; 33 ± 3 yr, 58 ± 6 kg, 163 ± 8 cm) completed a peak oxygen uptake (V̇O2peak) and submaximal exercise to exhaustion (EXH) test at 70% of their altitude-specific V̇O2peak at sea level (SL) and during an acute altitude (AA) exposure to 4300 m in a hypobaric chamber (446 mm Hg) in their early-follicular and midluteal menstrual cycle phase. The respiratory exchange ratio (RER) was calculated from oxygen uptake and carbon dioxide output measurements made during the EXH tests, and used to estimate the percent contribution of fat and carbohydrate to energy metabolism. Blood samples were taken at rest and every 15 min during the EXH tests. Blood samples were evaluated for glucose, lactate, glycerol, free fatty acids, insulin, growth hormone, cortisol, glucagon. epinephrine, norepinephrine, estradiol, and progesterone concentrations. Results: Despite increased (P < 0.05) estradiol and progesterone levels in the midluteal phase, substrate oxidation, energy substrates, and metabolic hormones were not affected by cycle phase at SL or AA. However, free fatty acids and cortisol were increased (P < 0.05) whereas RER was decreased (P < 0.05) during exercise upon AA exposure compared with SL in both cycle phases. Conclusions: These data suggest that substrate oxidation is altered in women during exercise at AA compared with SL but is not affected by cycle phase. Whether increased fat or protein oxidation accounts for the lower RER values during the AA exposure cannot be determined from this study but warrants further investigation.

Original languageEnglish
Pages (from-to)430-437
Number of pages8
JournalMedicine and Science in Sports and Exercise
Volume34
Issue number3
DOIs
StatePublished - 1 Jan 2002

Fingerprint

Exercise
Oceans and Seas
Nonesterified Fatty Acids
Progesterone
Hydrocortisone
Estradiol
Fats
Oxygen
Follicular Phase
Menstrual Cycle
Glucagon
Carbon Dioxide
Glycerol
Energy Metabolism
Epinephrine
Growth Hormone
Lactic Acid
Norepinephrine
Carbohydrates
Hormones

Keywords

  • Hypobaric hypoxia
  • Lactate
  • Menstrual cycle
  • Ovarian hormones
  • Respiratory exchange ratio

Cite this

Beidleman, Beth A. ; Rock, Paul B. ; Muza, Stephen R. ; Fulco, Charles S. ; Gibson, Lindsay L. ; Kamimori, Gary H. ; Cymerman, Allen. / Substrate oxidation is altered in women during exercise upon acute altitude exposure. In: Medicine and Science in Sports and Exercise. 2002 ; Vol. 34, No. 3. pp. 430-437.
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Substrate oxidation is altered in women during exercise upon acute altitude exposure. / Beidleman, Beth A.; Rock, Paul B.; Muza, Stephen R.; Fulco, Charles S.; Gibson, Lindsay L.; Kamimori, Gary H.; Cymerman, Allen.

In: Medicine and Science in Sports and Exercise, Vol. 34, No. 3, 01.01.2002, p. 430-437.

Research output: Contribution to journalArticle

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T1 - Substrate oxidation is altered in women during exercise upon acute altitude exposure

AU - Beidleman, Beth A.

AU - Rock, Paul B.

AU - Muza, Stephen R.

AU - Fulco, Charles S.

AU - Gibson, Lindsay L.

AU - Kamimori, Gary H.

AU - Cymerman, Allen

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AB - Purpose: The purpose of this study was to determine whether substrate oxidation during submaximal exercise in women is affected by an acute exposure to 4300-m altitude and menstrual cycle phase. Methods: Eight female lowlanders (mean ± SD; 33 ± 3 yr, 58 ± 6 kg, 163 ± 8 cm) completed a peak oxygen uptake (V̇O2peak) and submaximal exercise to exhaustion (EXH) test at 70% of their altitude-specific V̇O2peak at sea level (SL) and during an acute altitude (AA) exposure to 4300 m in a hypobaric chamber (446 mm Hg) in their early-follicular and midluteal menstrual cycle phase. The respiratory exchange ratio (RER) was calculated from oxygen uptake and carbon dioxide output measurements made during the EXH tests, and used to estimate the percent contribution of fat and carbohydrate to energy metabolism. Blood samples were taken at rest and every 15 min during the EXH tests. Blood samples were evaluated for glucose, lactate, glycerol, free fatty acids, insulin, growth hormone, cortisol, glucagon. epinephrine, norepinephrine, estradiol, and progesterone concentrations. Results: Despite increased (P < 0.05) estradiol and progesterone levels in the midluteal phase, substrate oxidation, energy substrates, and metabolic hormones were not affected by cycle phase at SL or AA. However, free fatty acids and cortisol were increased (P < 0.05) whereas RER was decreased (P < 0.05) during exercise upon AA exposure compared with SL in both cycle phases. Conclusions: These data suggest that substrate oxidation is altered in women during exercise at AA compared with SL but is not affected by cycle phase. Whether increased fat or protein oxidation accounts for the lower RER values during the AA exposure cannot be determined from this study but warrants further investigation.

KW - Hypobaric hypoxia

KW - Lactate

KW - Menstrual cycle

KW - Ovarian hormones

KW - Respiratory exchange ratio

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