Resistance exercise-induced increases in putative anabolic hormones do not enhance muscle protein synthesis or intracellular signalling in young men.
We aimed to determine whether exercise-induced elevations in systemic concentration of testosterone, growth hormone (GH) and insulin-like growth factor-1 (IGF-1) enhanced post-exercise myofibrillar protein synthesis (MPS) and phosphorylation of signalling proteins important in regulating mRNA translation. Eight young men (20 +/- 1.1 years, BMI = 26 +/- 3.5 kg m(-2)) completed two exercise protocols designed to maintain basal hormone concentrations (low hormone, LH) or elicit increases in endogenous hormones (high hormone, HH). In the LH protocol, participants performed a bout of unilateral resistance exercise with the elbow flexors. The HH protocol consisted of the same elbow flexor exercise with the contralateral arm followed immediately by high-volume leg resistance exercise. Participants consumed 25 g of protein after arm exercise to maximize MPS. Muscle biopsies and blood samples were taken as appropriate. There were no changes in serum testosterone, GH or IGF-1 after the LH protocol, whereas there were marked elevations after HH (testosterone, P < 0.001; GH, P < 0.001; IGF-1, P < 0.05). Exercise stimulated a rise in MPS in the biceps brachii (rest = 0.040 +/- 0.007, LH = 0.071 +/- 0.008, HH = 0.064 +/- 0.014% h(-1); P < 0.05) with no effect of elevated hormones (P = 0.72). Phosphorylation of the 70 kDa S6 protein kinase (p70S6K) also increased post-exercise (P < 0.05) with no differences between conditions. We conclude that the transient increases in endogenous purportedly anabolic hormones do not enhance fed-state anabolic signalling or MPS following resistance exercise. Local mechanisms are likely to be of predominant importance for the post-exercise increase in MPS.
West
Daniel W D
DW
Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada.
Kujbida
Gregory W
GW
Moore
Daniel R
DR
Atherton
Philip
P
Burd
Nicholas A
NA
Padzik
Jan P
JP
De Lisio
Michael
M
Tang
Jason E
JE
Parise
Gianni
G
Rennie
Michael J
MJ
Baker
Steven K
SK
Phillips
Stuart M
SM
D045930:Anabolic Agents / Q000097:blood; D013006:Growth Hormone / Q000097:blood*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*; D015398:Signal Transduction / Q000502:physiology*; D013739:Testosterone / Q000097:blood*; D055815:Young Adult
D045930:Anabolic Agents; D009124:Muscle Proteins; D013739:Testosterone; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone