Myogenic Gene Expression at Rest & Following Resistance Exercise in Young (18-30y)& Old

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J Appl Physiol. 2006 Apr

Myogenic Gene Expression at Rest and Following a Bout of Resistance Exercise in

Young (18-30 y) and Old (80-89 y) Women.

Raue U, Slivka D, Jemiolo B, Hollon C, Trappe SW.

Human Performance Laboratory, Ball State University, Muncie, Indiana, United

States.

The purpose of this study was to investigate mRNA expression of several key

skeletal muscle myogenic controllers; myogenic differentiation factor (MyoD),

muscle regulatory factor 4 (MRF4), myogenic factor 5 (Myf5), Myogenin,

Myostatin, and myocyte enhancer factor 2 (MEF2) at rest and 4 hrs after a single

bout of resistance exercise (RE) in young and old women. Eight young women (YW)

(23+/-2 y, 67+/-5 kg) and 6 old women (OW) (85+/-1 y, 67+/-4 kg) performed 3

sets of 10 repetitions of bilateral knee extensions at 70% of 1-repetition

maximum. Muscle biopsies were taken from the vastus lateralis before and 4 hrs

after RE. Using real-time RT PCR, mRNA from the muscle samples was amplified and

normalized to GAPDH. At rest, OW expressed higher (p<0.05) levels of MyoD, MRF4,

Myf5, Myogenin, and Myostatin compared to YW. In response to RE, there was a

main time-effect (p<0.05) for the YW and OW combined in the up regulation of

MyoD (2.0 fold), MRF4 (1.4-fold), and in the down regulation of Myostatin

(2.2-fold). There was a trend (p=0.08) for time x age interaction in MRF4. These

data show that old women express higher myogenic mRNA levels at rest. The higher

resting myogenic mRNA levels in old women may reflect an attempt to preserve

muscle mass and function. When challenged with RE, old women appear to respond

in a similar manner as young women.

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