Androgenic Responses to Resistance Exercise: Effects of Feeding and L-Carnitine

Document Type

Journal Article


Faculty of Computing, Health and Science


School of Exercise, Biomedical and Health Science, Centre for Alzheimer's Disease




Kraemer, W. J., Spiering, B. A., Volek, J. S., Ratamess, N. A., Sharman, M. J., Rubin, M. R., ... & Vingren, J. L. (2006). Androgenic responses to resistance exercise: effects of feeding and L-carnitine. Medicine & Science in Sports & Exercise, 38(7), 1288-1296.


Purpose: The purpose of this investigation was to determine the effects of 3 wk of L-carnitine L-tartrate (LCLT) supplementation and post Yresistance-exercise (RE) feeding on hormonal and androgen receptor (AR) responses. Methods: Ten resistance-trained men (mean T SD: age, 22 T 1 yr; mass, 86.3 T 15.3 kg; height, 181 T 11 cm) supplemented with LCLT (equivalent to 2 g of L-carnitine per day) or placebo (PL) for 21 d, provided muscle biopsies for AR determinations, then performed two RE protocols: one followed by water intake, and one followed by feeding (8 kcalIkgj1 body mass, consisting of 56% carbohydrate, 16% protein, and 28% fat). RE protocols were randomized and included serial blood draws and a 1-h post-RE biopsy. After a 7-d washout period, subjects crossed over, and all experimental procedures were repeated. Results: LCLT supplementation upregulated (P G 0.05) preexercise AR content compared with PL (12.9 T 5.9 vs 11.2 T 4.0 au, respectively). RE increased (P G 0.05) AR content compared with pre-RE values in the PL trial only. Post-RE feeding significantly increased AR content compared with baseline and water trials for both LCLT and PL. Serum total testosterone concentrations were suppressed (P G 0.05) during feeding trials with respect to corresponding water and pre-RE values. Luteinizing hormone demonstrated subtle, yet significant changes in response to feeding and LCLT. Conclusion: In summary, these data demonstrated that: 1) feeding after RE increased AR content, which may result in increased testosterone uptake, and thus enhanced luteinizing hormone secretion via feedback mechanisms; and 2) LCLT supplementation upregulated AR content, which may promote recovery from RE.



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