Women at altitude: Carbohydrate utilization during exercise at 4,300 m

Barry Braun, Jacinda T. Mawson, Stephen R. Muza, Shannon B. Dominick, George A. Brooks, Michael A. Horning, Paul B. Rock, Lorna G. Moore, Robert S. Mazzeo, Steven C. Ezeji-Okoye, Gail E. Butterfield

Research output: Contribution to journalArticle

87 Citations (Scopus)

Abstract

To evaluate the hypothesis that exposure to high altitude would reduce blood glucose and total carbohydrate utilization relative to sea level (SL), 16 young women were studied over four 12-day periods: at 50% of peak O2 consumption in different menstrual cycle phases (SL-50), at 65% of peak O2 consumption at SL (SL-65), and at 4,300 m (HA). After 10 days in each condition, blood glucose rate of disappearance (R(d)) and respiratory exchange ratio were measured at rest and during 45 min of exercise. Glucose R(d) during exercise at HA (4.71 ± 0.30 mg·kg-1·min-1) was not different from SL exercise at the same absolute intensity (SL-50 = 5.03 mg·kg-1·min-1) but was lower at the same relative intensity (SL-65 = 6.22 mg· kg-1·min-1, P < 0.01). There were no differences, however, when glucose R(d) was corrected for energy expended (kcal/min) during exercise. Respiratory exchange ratios followed the same pattern, except Carbohydrate oxidation remained lower (-23.2%, P < 0.01) at HA than at SL when corrected for energy expended. In women, unlike in men, carbohydrate utilization decreased at HA. Relative abundance of estrogen and progesterone in women may partially explain the sex differences in fuel utilization at HA, but subtle differences between menstrual cycle phases at SL had no physiologically relevant effects.

Original languageEnglish
Pages (from-to)246-256
Number of pages11
JournalJournal of Applied Physiology
Volume88
Issue number1
StatePublished - 1 Jan 2000

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Oceans and Seas
Carbohydrates
Exercise
Menstrual Cycle
Blood Glucose
Glucose
Respiratory Rate
Sex Characteristics
Progesterone
Estrogens

Keywords

  • Gender differences
  • Glucose flux
  • Hypobaric hypoxia
  • Menstrual cycle
  • Ovarian hormones
  • Stable isotope
  • Substrate utilization

Cite this

Braun, B., Mawson, J. T., Muza, S. R., Dominick, S. B., Brooks, G. A., Horning, M. A., ... Butterfield, G. E. (2000). Women at altitude: Carbohydrate utilization during exercise at 4,300 m. Journal of Applied Physiology, 88(1), 246-256.
Braun, Barry ; Mawson, Jacinda T. ; Muza, Stephen R. ; Dominick, Shannon B. ; Brooks, George A. ; Horning, Michael A. ; Rock, Paul B. ; Moore, Lorna G. ; Mazzeo, Robert S. ; Ezeji-Okoye, Steven C. ; Butterfield, Gail E. / Women at altitude : Carbohydrate utilization during exercise at 4,300 m. In: Journal of Applied Physiology. 2000 ; Vol. 88, No. 1. pp. 246-256.
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abstract = "To evaluate the hypothesis that exposure to high altitude would reduce blood glucose and total carbohydrate utilization relative to sea level (SL), 16 young women were studied over four 12-day periods: at 50{\%} of peak O2 consumption in different menstrual cycle phases (SL-50), at 65{\%} of peak O2 consumption at SL (SL-65), and at 4,300 m (HA). After 10 days in each condition, blood glucose rate of disappearance (R(d)) and respiratory exchange ratio were measured at rest and during 45 min of exercise. Glucose R(d) during exercise at HA (4.71 ± 0.30 mg·kg-1·min-1) was not different from SL exercise at the same absolute intensity (SL-50 = 5.03 mg·kg-1·min-1) but was lower at the same relative intensity (SL-65 = 6.22 mg· kg-1·min-1, P < 0.01). There were no differences, however, when glucose R(d) was corrected for energy expended (kcal/min) during exercise. Respiratory exchange ratios followed the same pattern, except Carbohydrate oxidation remained lower (-23.2{\%}, P < 0.01) at HA than at SL when corrected for energy expended. In women, unlike in men, carbohydrate utilization decreased at HA. Relative abundance of estrogen and progesterone in women may partially explain the sex differences in fuel utilization at HA, but subtle differences between menstrual cycle phases at SL had no physiologically relevant effects.",
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Braun, B, Mawson, JT, Muza, SR, Dominick, SB, Brooks, GA, Horning, MA, Rock, PB, Moore, LG, Mazzeo, RS, Ezeji-Okoye, SC & Butterfield, GE 2000, 'Women at altitude: Carbohydrate utilization during exercise at 4,300 m', Journal of Applied Physiology, vol. 88, no. 1, pp. 246-256.

Women at altitude : Carbohydrate utilization during exercise at 4,300 m. / Braun, Barry; Mawson, Jacinda T.; Muza, Stephen R.; Dominick, Shannon B.; Brooks, George A.; Horning, Michael A.; Rock, Paul B.; Moore, Lorna G.; Mazzeo, Robert S.; Ezeji-Okoye, Steven C.; Butterfield, Gail E.

In: Journal of Applied Physiology, Vol. 88, No. 1, 01.01.2000, p. 246-256.

Research output: Contribution to journalArticle

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T2 - Carbohydrate utilization during exercise at 4,300 m

AU - Braun, Barry

AU - Mawson, Jacinda T.

AU - Muza, Stephen R.

AU - Dominick, Shannon B.

AU - Brooks, George A.

AU - Horning, Michael A.

AU - Rock, Paul B.

AU - Moore, Lorna G.

AU - Mazzeo, Robert S.

AU - Ezeji-Okoye, Steven C.

AU - Butterfield, Gail E.

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Y1 - 2000/1/1

N2 - To evaluate the hypothesis that exposure to high altitude would reduce blood glucose and total carbohydrate utilization relative to sea level (SL), 16 young women were studied over four 12-day periods: at 50% of peak O2 consumption in different menstrual cycle phases (SL-50), at 65% of peak O2 consumption at SL (SL-65), and at 4,300 m (HA). After 10 days in each condition, blood glucose rate of disappearance (R(d)) and respiratory exchange ratio were measured at rest and during 45 min of exercise. Glucose R(d) during exercise at HA (4.71 ± 0.30 mg·kg-1·min-1) was not different from SL exercise at the same absolute intensity (SL-50 = 5.03 mg·kg-1·min-1) but was lower at the same relative intensity (SL-65 = 6.22 mg· kg-1·min-1, P < 0.01). There were no differences, however, when glucose R(d) was corrected for energy expended (kcal/min) during exercise. Respiratory exchange ratios followed the same pattern, except Carbohydrate oxidation remained lower (-23.2%, P < 0.01) at HA than at SL when corrected for energy expended. In women, unlike in men, carbohydrate utilization decreased at HA. Relative abundance of estrogen and progesterone in women may partially explain the sex differences in fuel utilization at HA, but subtle differences between menstrual cycle phases at SL had no physiologically relevant effects.

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KW - Hypobaric hypoxia

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KW - Ovarian hormones

KW - Stable isotope

KW - Substrate utilization

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Braun B, Mawson JT, Muza SR, Dominick SB, Brooks GA, Horning MA et al. Women at altitude: Carbohydrate utilization during exercise at 4,300 m. Journal of Applied Physiology. 2000 Jan 1;88(1):246-256.