Postexercise Myostatin and Activin IIb mRNA Levels: Effects of Strength Training

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Med Sci Sports Exerc. 2007 Feb;39(2):289-297.

Postexercise Myostatin and Activin IIb mRNA Levels: Effects of

Strength Training.

Hulmi JJ, Ahtiainen JP, Kaasalainen T, Pollanen E, Hakkinen K, Alen

M, Selanne H, Kovanen V, Mero AA.

1Department of Biology of Physical Activity and Neuromuscular

Research Center, 2Department of Health Sciences, 3Department of

Chemistry, and 4Finnish Centre for Interdisciplinary Gerontology,

University of Jyvaskyla, Jyvaskyla, FINLAND; and 5LIKES Research

Center, Jyvaskyla, FINLAND.

PURPOSE:: Muscle hypertrophy is likely to result from the cumulative

effects of repeated bouts of resistance exercise (RE) on

postexercise molecular responses. Therefore, we determined muscle

growth- and regeneration-related mRNA expression in response to a

single RE bout both before and after a strength-training (ST)

period. By means of this novel longitudinal setting, we examined

whether postexercise gene expression at the transcriptional level is

different in the trained and untrained state.

METHODS:: Eleven untrained healthy older men and 11 controls (age

62.3 +/- 6.3 yr) volunteered as subjects. Muscle biopsies from the

vastus lateralis muscle were taken at rest and 1 and 48 h after five

sets of 10-repetition leg press RE both before and after 21 wk of

supervised ST.

RESULTS:: Myostatin and myogenin mRNA expression, determined by real-

time RT-PCR, increased (P < 0.05) after ST. Conversely, the single

RE bout decreased myostatin mRNA after ST, with the decrease showing

a negative correlation (r = -0.65, P < 0.05) with the long-term

increase in myostatin during ST. Furthermore, RE before ST increased

myogenin mRNA (P < 0.05) and tended to increase after ST (P = 0.08).

Myostatin receptor activin IIb mRNA levels were decreased at 1 h

after RE in the pre-ST condition (P = 0.05) and also tended to

decrease in the post-ST condition (P = 0.07). RE-induced

downregulation in myostatin mRNA correlated with the ST-induced

increase in total body muscle mass (r = -0.82, P = 0.002).

CONCLUSIONS:: A single bout of RE in older men can downregulate the

expression of myostatin receptor activin IIb mRNA. ST influences the

response of myostatin to RE, as short-term RE-induced downregulation

of myostatin was observed only after ST. The results also indicate

that RE-induced alterations in myostatin mRNA expression may have a

role in ST-induced muscle hypertrophy.