Myonuclei acquired by overload exercise precede hypertrophy and are not lost on detra

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Myonuclei acquired by overload exercise precede hypertrophy and are not lost on detraining

Myonuclei acquired by overload exercise precede hypertrophy and are not lost on detraining

J. C. Bruusgaard, I. B. Johansen, I. M. Egner, Z. A. Rana, and K. Gundersen 1

Department of Molecular Biosciences, University of Oslo, 0371 Oslo, Norway

Edited by Gerald D. Fischbach, The Simons Foundation, New York, NY, and approved July 16, 2010 (received for review December 4, 2009)


Effects of previous strength training can be long-lived, even after prolonged subsequent inactivity, and retraining is facilitated by a previous training episode. Traditionally, such “muscle memory” has been attributed to neural factors in the absence of any identified local memory mechanism in the muscle tissue. We have used in vivo imaging techniques to study live myonuclei belonging to distinct muscle fibers and observe that new myonuclei are added before any major increase in size during overload. The old and newly acquired nuclei are retained during severe atrophy caused by subsequent denervation lasting for a considerable period of the animal’s lifespan. The myonuclei seem to be protected from the high apoptotic activity found in inactive muscle tissue. A hypertrophy episode leading to a lasting elevated number of myonuclei retarded disuse atrophy, and the nuclei could serve as a cell biological substrate for such memory. Because the ability to create myonuclei is impaired in the elderly, individuals may benefit from strength training at an early age, and because anabolic steroids facilitate more myonuclei, nuclear permanency may also have implications for exclusion periods after a doping offense.
 
So perhaps there is some validity to the frequently misused term ''muscle memory''.

Unfortunately, it also appears that memory fades with age...
 
I finally got a chance to read this one and it is quite interesting indeed especially the previously thought ideas concerning apoptosis.
 
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