Enter your Email address:
Wolters Kluwer Health may email you for journal alerts and information, but is committed
to maintaining your privacy and will not share your personal information without
Braun, Barry FACSM1; Gerson, Laura1; Hagobian, Todd1; Grow, Daniel2; Chipkin, Stuart2
1University of Massachusetts, Amherst, MA.
2Baystate Medical Center, Springfield, MA.
Men use proportionately more carbohydrate and less fat during submaximal exercise than women and circulating hormones appear to play a role in mediating this difference. We have shown that circulating estrogen and progesterone have potent and opposing effects on the regulation of substrate use during exercise in women, but the role of testosterone in mediating exercise substrate use in men is unknown. We tested the hypothesis that high concentrations of testosterone (T) would shift substrate use toward greater carbohydrate utilization. Nine healthy active men cycled at ∼60% of VO2peak for 90 min under 3 hormonal conditions: physiological T (no intervention), low T (pharmacological suppression of endogenous T with GnRH antagonist) and high T (supplementation with transdermal T). Total plasma testosterone was significantly different between physiological T, low T, and high T (mean±SEM, 5.5±0.4 ng/ml, 0.8±0.1, 10.9±1.0 (p < 0.0001), respectively). Despite the large change in plasma T, there were no differences in carbohydrate oxidation (27.1± 1.7 mg/kg/min, 25.5±2.0, 24.9±1.4 (p=0.68)) or lipid oxidation (5.1±0.7 mg/kg/min, 5.4±0.6, 5.9±0.4 (p=0.60)). Furthermore, blood glucose uptake (8.3±0.7 mg/kg/min, 8.2±0.7, 7.8±0.7 (p=0.88)) and estimated muscle glycogen utilization (18.8±1.6 mg/kg/min, 17.2±1.7, 17.1±1.1(p=0.66)), as measured using stable isotope dilution and indirect calorimetry, were not different between T conditions. In conclusion, circulating T does not alter carbohydrate oxidation or blood glucose uptake during submaximal exercise. These data indicate that circulating T does not play a direct role in the observed gender difference in submaximal exercise carbohydrate oxidation.
©2005The American College of Sports Medicine
Colleague's E-mail is Invalid
Your Name: (optional)
Separate multiple e-mails with a (;).
Thought you might appreciate this item(s) I saw at Medicine & Science in Sports & Exercise.
Send a copy to your email
Your message has been successfully sent to your colleague.
Some error has occurred while processing your request. Please try after some time.
An Existing Folder
A New Folder
The item(s) has been successfully added to "".
Login with your LWW Journals username and password.
Username or Email:
Enter and submit the email address you registered with. An email with instructions to reset your password will be sent to that address.
Link to reset your password has been sent to specified email address.
What does "Remember me" mean?
By checking this box, you'll stay logged in until you logout. You'll get easier access to your articles, collections,
media, and all your other content, even if you close your browser or shut down your
To protect your most sensitive data and activities (like changing your password),
we'll ask you to re-enter your password when you access these services.
What if I'm on a computer that I share with others?
If you're using a public computer or you share this computer with others, we recommend
that you uncheck the "Remember me" box.
Save my selection
Article Level Metrics