PMID- 15755861
OWN - NLM
STAT- MEDLINE
DCOM- 20050705
LR  - 20220309
IS  - 0021-972X (Print)
IS  - 0021-972X (Linking)
VI  - 90
IP  - 6
DP  - 2005 Jun
TI  - Estrogen supplementation reduces whole body leucine and carbohydrate oxidation 
      and increases lipid oxidation in men during endurance exercise.
PG  - 3592-9
AB  - Healthy active men exhibit higher rates of carbohydrate (CHO) and leucine 
      oxidation and lower rates of lipid oxidation compared with their female 
      counterparts both at rest and during moderate intensity endurance exercise. We 
      postulated that this reduced dependence on amino acids as a fuel source in women 
      was due to the female sex hormone estrogen. In a randomized, double-blind, 
      placebo-controlled, cross-over design, we investigated the effect of 
      supplementing 12 recreationally active men with estrogen on whole body substrate 
      oxidation and leucine kinetics at rest and during moderate intensity endurance 
      exercise. Subjects cycled for 90 min at an intensity of 65% maximum O(2) 
      consumption after 8 d of either estrogen supplementation (2 mg 
      17beta-estradiol/d) or placebo (polycose). After a 2-wk washout period, they 
      repeated the test after 8 d of the alternate treatment. On the test day, after a 
      primed continuous infusion of l-[(13)C]leucine, O(2) consumption, CO(2) 
      production, steady-state breath (13)CO(2), and plasma 
      alpha-[(13)C]ketoisocaproate enrichments were measured at rest and at 60, 75, and 
      90 min during exercise in the postabsorptive state. Exercise increased energy 
      expenditure more than 5-fold, CHO oxidation more than 6-fold, lipid oxidation 
      more than 4-fold, and leucine oxidation 2.2-fold (all P < 0.0001), whereas it 
      decreased the ratio of lipid to CHO oxidation by 50-70% (P = 0.003) compared with 
      values at rest. Estrogen supplementation decreased respiratory exchange ratio 
      during exercise (P = 0.03). Estrogen supplementation significantly decreased CHO 
      oxidation by 5-16% (P = 0.04) and leucine oxidation by 16% (P = 0.01), whereas it 
      significantly increased lipid oxidation by 22-44% (P = 0.024) at rest and during 
      exercise. We conclude that estrogen influences fuel source selection at rest and 
      during endurance exercise in recreationally active men, characterized by a 
      reduced dependence on amino acids and CHO and an increased reliance on lipids as 
      a fuel source.
FAU - Hamadeh, Mazen J
AU  - Hamadeh MJ
AD  - Department of Pediatrics and Medicine, McMaster University Medical Center, 1200 
      Main Street West, Hamilton, Ontario, Canada L8N 3Z5.
FAU - Devries, Michaela C
AU  - Devries MC
FAU - Tarnopolsky, Mark A
AU  - Tarnopolsky MA
LA  - eng
PT  - Clinical Trial
PT  - Journal Article
PT  - Randomized Controlled Trial
PT  - Research Support, Non-U.S. Gov't
DEP - 20050308
PL  - United States
TA  - J Clin Endocrinol Metab
JT  - The Journal of clinical endocrinology and metabolism
JID - 0375362
RN  - 0 (Estrogens)
RN  - 0 (Placebos)
RN  - 3XMK78S47O (Testosterone)
RN  - 4G7DS2Q64Y (Progesterone)
RN  - 4TI98Z838E (Estradiol)
RN  - GMW67QNF9C (Leucine)
SB  - IM
MH  - Adult
MH  - *Carbohydrate Metabolism
MH  - Cross-Over Studies
MH  - Double-Blind Method
MH  - Energy Metabolism/drug effects
MH  - Estradiol/blood/*pharmacology
MH  - Estrogens/*pharmacology
MH  - Female
MH  - Humans
MH  - Leucine/*metabolism
MH  - *Lipid Metabolism
MH  - Male
MH  - Oxidation-Reduction
MH  - Oxygen Consumption/drug effects
MH  - *Physical Endurance
MH  - Placebos
MH  - Progesterone/blood
MH  - Reference Values
MH  - Testosterone
EDAT- 2005/03/10 09:00
MHDA- 2005/07/06 09:00
CRDT- 2005/03/10 09:00
PHST- 2005/03/10 09:00 [pubmed]
PHST- 2005/07/06 09:00 [medline]
PHST- 2005/03/10 09:00 [entrez]
AID - jc.2004-1743 [pii]
AID - 10.1210/jc.2004-1743 [doi]
PST - ppublish
SO  - J Clin Endocrinol Metab. 2005 Jun;90(6):3592-9. doi: 10.1210/jc.2004-1743. Epub 
      2005 Mar 8.