TY - JOUR
T1 - Women at altitude
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.
PY - 2000/1
Y1 - 2000/1
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.
AB - 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.
KW - Gender differences
KW - Glucose flux
KW - Hypobaric hypoxia
KW - Menstrual cycle
KW - Ovarian hormones
KW - Stable isotope
KW - Substrate utilization
UR - http://www.scopus.com/inward/record.url?scp=0033954437&partnerID=8YFLogxK
U2 - 10.1152/jappl.2000.88.1.246
DO - 10.1152/jappl.2000.88.1.246
M3 - Article
C2 - 10642387
AN - SCOPUS:0033954437
SN - 8750-7587
VL - 88
SP - 246
EP - 256
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 1
ER -