title: Androgenic responses to resistance exercise: effects of feeding and L-carnitine.
abstract: OBJECTIVE
  The purpose of this investigation was to determine the effects of 3 wk of L-carnitine L-tartrate (LCLT) supplementation and post-resistance-exercise (RE) feeding on hormonal and androgen receptor (AR) responses.
  
  
  METHODS
  Ten resistance-trained men (mean+/-SD: age, 22+/-1 yr; mass, 86.3+/-15.3 kg; height, 181+/-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 kcal.kg 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<0.05) preexercise AR content compared with PL (12.9+/-5.9 vs 11.2+/-4.0 au, respectively). RE increased (P<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<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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269-1110, USA. William.Kraemer@uconn.edu
authors.forename: William J
authors.initials: WJ
authors.lastname: Kraemer
authors.forename: Barry A
authors.initials: BA
authors.lastname: Spiering
authors.forename: Jeff S
authors.initials: JS
authors.lastname: Volek
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Ratamess
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Sharman
authors.forename: Martyn R
authors.initials: MR
authors.lastname: Rubin
authors.forename: Duncan N
authors.initials: DN
authors.lastname: French
authors.forename: Ricardo
authors.initials: R
authors.lastname: Silvestre
authors.forename: Disa L
authors.initials: DL
authors.lastname: Hatfield
authors.forename: Jaci L
authors.initials: JL
authors.lastname: Van Heest
authors.forename: Jakob L
authors.initials: JL
authors.lastname: Vingren
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Judelson
authors.forename: Michael R
authors.initials: MR
authors.lastname: Deschenes
authors.forename: Carl M
authors.initials: CM
authors.lastname: Maresh
mesh_terms: D000328:Adult; D002331:Carnitine / Q000008:administration & dosage / Q000378:metabolism*; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D006801:Humans; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D010919:Placebos; D011944:Receptors, Androgen / Q000378:metabolism*; D014481:United States; D014803:Vitamin B Complex / Q000008:administration & dosage / Q000378:metabolism*; D014891:Weight Lifting / Q000502:physiology*
chemical_list: D010919:Placebos; D011944:Receptors, Androgen; D014803:Vitamin B Complex; D007986:Luteinizing Hormone; D002331:Carnitine