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Muscle Nerve. 2013 May;47(5):748-59. doi: 10.1002/mus.23667. Epub 2013 Mar 21.

Myogenic, matrix, and growth factor mRNA expression in human skeletal muscle: effect of contraction intensity and feeding.

Author information

1
Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital, Denmark. jakobagergaard@hotmail.com

Abstract

INTRODUCTION:

We examined short-term (3-hour) and long-term (12-week) training effects after heavy load [HL; 70% 1RM] and light load (LL; 16% 1RM) exercise.

METHODS:

mRNA expression of genes involved in skeletal muscle remodeling were analyzed and muscle activity (EMG measurements) was measured.

RESULTS:

Relative muscle activity differed between HL and LL resistance exercise, whereas median power frequency was even, suggesting an equal muscle-fiber-type recruitment distribution. mRNA expression of Myf6, myogenin, and p21 was mostly increased, and myostatin was mostly depressed by HL resistance exercise. No major differences were seen in atrophy-related genes between HL and LL resistance exercise. No changes were seen over 12-week training for any of the targets.

CONCLUSIONS:

Resistance exercise at LL and HL elevated the expression of genes involved in skeletal muscle hypertrophy, although the greatest response was from HL. However, no long-term effect from either LL or HL resistance exercise was seen on basal levels of the mRNA targets.

PMID:
23519763
DOI:
10.1002/mus.23667
[Indexed for MEDLINE]

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