| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Department of Physiology and Biophysics, University of Alabama at Birmingham, GRECC /11G, VA Medical Center, Birmingham, Alabama, 35294-0001, United States; Geriatric Research, Education, and Clinical Center, VA Medical Center, Birmingham, Alabama, United States
2 Department of Physiology and Biophysics, University of Alabama at Birmingham, GRECC /11G, VA Medical Center, Birmingham, Alabama, 35294-0001, United States
3 Surgery, University of Alabama at Birmingham, Birmingham, Alabama, United States
* To whom correspondence should be addressed. E-mail: mbamman{at}uab.edu.
A present debate in muscle biology is whether myonuclear addition is required during skeletal muscle hypertrophy. We utilized K-means cluster analysis to classify 66 humans after 16 wk of knee extensor resistance training as extreme (Xtr, n=17), modest (Mod, n=32), or non-responders (Non, n=17) based on myofiber hypertrophy, which averaged 58%, 28%, and 0%, respectively (Bamman et al. 2007). We hypothesized that robust hypertrophy seen in Xtr was driven by superior satellite cell (SC) activation and myonuclear addition. Vastus lateralis biopsies were obtained at baseline and wk 16. SCs were identified immunohistochemically by surface expression of neural cell adhesion molecule. At baseline, myofiber size did not differ among clusters; however, the SC population was greater in Xtr (P<0.01) than both Mod and Non, suggesting superior basal myogenic potential. SC number increased robustly during training in Xtr only (117%, P<0.001). Myonuclear addition occurred in Mod (9%, P<0.05) and was most effectively accomplished in Xtr (26%, P<0.001). After training, Xtr had more myonuclei per fiber than Non (23%, P<0.05) and tended to have more than Mod (19%, P=0.056). Both Xtr and Mod expanded the myonuclear domain to meet (Mod) or exceed (Xtr) 2000 µm2 per nucleus, possibly driving demand for myonuclear addition to support myofiber expansion. These findings strongly suggest myonuclear addition via SC recruitment may be required to achieve substantial myofiber hypertrophy in humans. Individuals with a greater basal presence of SCs demonstrated, with training, a remarkable ability to expand the SC pool, incorporate new nuclei, and achieve robust growth.
This article has been cited by other articles:
|
|
 |
|
  D. L. Mayhew, J.-s. Kim, J. M. Cross, A. A. Ferrando, and M. M. Bamman Translational signaling responses preceding resistance training-mediated myofiber hypertrophy in young and old humans J Appl Physiol, November 1, 2009; 107(5): 1655 - 1662. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Suetta, L. G. Hvid, L. Justesen, U. Christensen, K. Neergaard, L. Simonsen, N. Ortenblad, S. P. Magnusson, M. Kjaer, and P. Aagaard Effects of aging on human skeletal muscle after immobilization and retraining J Appl Physiol, October 1, 2009; 107(4): 1172 - 1180. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. B. Verdijk, B. G. Gleeson, R. A. M. Jonkers, K. Meijer, H. H. C. M. Savelberg, P. Dendale, and L. J. C. van Loon Skeletal Muscle Hypertrophy Following Resistance Training Is Accompanied by a Fiber Type-Specific Increase in Satellite Cell Content in Elderly Men J Gerontol A Biol Sci Med Sci, March 1, 2009; 64A(3): 332 - 339. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
