Bortz, W.M. II. A conceptual framework of frailty: a review. J. Gerontol. A Biol. Sci. Med. Sci. 57, M283–M288 (2002).
Mitchell, W.K. et al. Sarcopenia, dynapenia, and the impact of advancing age on human skeletal muscle size and strength; a quantitative review. Front. Physiol. 3, 260 (2012).
García-Prat, L., Sousa-Victor, P. & Muñoz-Cánoves, P. Functional dysregulation of stem cells during aging: a focus on skeletal muscle stem cells. FEBS J. 280, 4051–4062 (2013).
Gopinath, S.D. & Rando, T.A. Stem cell review series: aging of the skeletal muscle stem cell niche. Aging Cell 7, 590–598 (2008).
Topinková, E. Aging, disability and frailty. Ann. Nutr. Metab. 52 (suppl. 1), 6–11 (2008).
Walston, J. et al. Research agenda for frailty in older adults: toward a better understanding of physiology and etiology: summary from the American Geriatrics Society/National Institute on Aging Research Conference on Frailty in Older Adults. J. Am. Geriatr. Soc. 54, 991–1001 (2006).
Sinha, M. et al. Restoring systemic GDF11 levels reverses age-related dysfunction in mouse skeletal muscle. Science 344, 649–652 (2014).
Collins, C.A., Zammit, P.S., Ruiz, A.P., Morgan, J.E. & Partridge, T.A. A population of myogenic stem cells that survives skeletal muscle aging. Stem Cells 25, 885–894 (2007).
Shefer, G., Van de Mark, D.P., Richardson, J.B. & Yablonka-Reuveni, Z. Satellite-cell pool size does matter: defining the myogenic potency of aging skeletal muscle. Dev. Biol. 294, 50–66 (2006).
Chakkalakal, J.V., Jones, K.M., Basson, M.A. & Brack, A.S. The aged niche disrupts muscle stem cell quiescence. Nature 490, 355–360 (2012).
Bernet, J.D. et al. p38 MAPK signaling underlies a cell-autonomous loss of stem cell self-renewal in skeletal muscle of aged mice. Nat. Med. 20, 265–271 (2014).
Brack, A.S. et al. Increased Wnt signaling during aging alters muscle stem cell fate and increases fibrosis. Science 317, 807–810 (2007).
Carlson, M.E. & Conboy, I.M. Loss of stem cell regenerative capacity within aged niches. Aging Cell 6, 371–382 (2007).
Conboy, I.M. et al. Rejuvenation of aged progenitor cells by exposure to a young systemic environment. Nature 433, 760–764 (2005).
Cosgrove, B.D. et al. Rejuvenation of the muscle stem cell population restores strength to injured aged muscles. Nat. Med. 20, 255–264 (2014).
McKay, B.R. et al. Elevated SOCS3 and altered IL-6 signaling is associated with age-related human muscle stem cell dysfunction. Am. J. Physiol. Cell Physiol. 304, C717–C728 (2013).
Shefer, G., Rauner, G., Yablonka-Reuveni, Z. & Benayahu, D. Reduced satellite cell numbers and myogenic capacity in aging can be alleviated by endurance exercise. PLoS ONE 5, e13307 (2010).
Sousa-Victor, P. et al. Geriatric muscle stem cells switch reversible quiescence into senescence. Nature 506, 316–321 (2014).
Fry, C.S. et al. Regulation of the muscle fiber microenvironment by activated satellite cells during hypertrophy. FASEB J. 28, 1654–1665 (2014).
Jackson, J.R. et al. Satellite cell depletion does not inhibit adult skeletal muscle regrowth following unloading-induced atrophy. Am. J. Physiol. Cell Physiol. 303, C854–C861 (2012).
McCarthy, J.J. et al. Effective fiber hypertrophy in satellite cell-depleted skeletal muscle. Development 138, 3657–3666 (2011).
Lepper, C., Partridge, T.A. & Fan, C.M. An absolute requirement for Pax7-positive satellite cells in acute injury-induced skeletal muscle regeneration. Development 138, 3639–3646 (2011).
Murphy, M.M., Lawson, J.A., Mathew, S.J., Hutcheson, D.A. & Kardon, G. Satellite cells, connective tissue fibroblasts and their interactions are crucial for muscle regeneration. Development 138, 3625–3637 (2011).
Sambasivan, R. et al. Pax7-expressing satellite cells are indispensable for adult skeletal muscle regeneration. Development 138, 3647–3656 (2011).
Baumgartner, R.N. et al. Epidemiology of sarcopenia among the elderly in New Mexico. Am. J. Epidemiol. 147, 755–763 (1998).
Larsson, L. Motor units—remodeling in aged animals. J. Gerontol. A Biol. Sci. Med. Sci. 50, 91–95 (1995).
Brack, A.S., Bildsoe, H. & Hughes, S.M. Evidence that satellite cell decrement contributes to preferential decline in nuclear number from large fibres during murine age-related muscle atrophy. J. Cell Sci. 118, 4813–4821 (2005).
Yu, F., Hedstrom, M., Cristea, A., Dalen, N. & Larsson, L. Effects of ageing and gender on contractile properties in human skeletal muscle and single fibres. Acta Physiol. (Oxf.) 190, 229–241 (2007).
Sinaki, M., Nwaogwugwu, N.C., Phillips, B.E. & Mokri, M. Effect of gender, age, and anthropometry on axial and appendicular muscle strength. Am. J. Phys. Med. Rehabil. 80, 330–338 (2001).
Shephard, R.J., Montelpare, W., Plyley, M., McCracken, D. & Goode, R.C. Handgrip dynamometry, Cybex measurements and lean mass as markers of the ageing of muscle function. Br. J. Sports Med. 25, 204–208 (1991).
Morrison, J., Lu, Q.L., Pastoret, C., Partridge, T. & Bou-Gharios, G. T-cell-dependent fibrosis in the mdx dystrophic mouse. Lab. Invest. 80, 881–891 (2000).
Dor, Y., Brown, J., Martinez, O.I. & Melton, D.A. Adult pancreatic beta-cells are formed by self-duplication rather than stem-cell differentiation. Nature 429, 41–46 (2004).
Humphreys, B.D. et al. Intrinsic epithelial cells repair the kidney after injury. Cell Stem Cell 2, 284–291 (2008).
Miyaoka, Y. et al. Hypertrophy and unconventional cell division of hepatocytes underlie liver regeneration. Curr. Biol. 22, 1166–1175 (2012).
Teta, M., Rankin, M.M., Long, S.Y., Stein, G.M. & Kushner, J.A. Growth and regeneration of adult beta cells does not involve specialized progenitors. Dev. Cell 12, 817–826 (2007).
Jones, D.A. et al. Moderate leisure-time physical activity: who is meeting the public health recommendations? A national cross-sectional study. Arch. Fam. Med. 7, 285–289 (1998).
Law, P.K. et al. Feasibility, safety, and efficacy of myoblast transfer therapy on Duchenne muscular dystrophy boys. Cell Transplant. 1, 235–244 (1992).
He, W.A. et al. NF-κB-mediated Pax7 dysregulation in the muscle microenvironment promotes cancer cachexia. J. Clin. Invest. 123, 4821–4835 (2013).
Bareja, A. & Billin, A.N. Satellite cell therapy—from mice to men. Skelet. Muscle 3, 2 (2013).
Nishijo, K. et al. Biomarker system for studying muscle, stem cells, and cancer in vivo. FASEB J. 23, 2681–2690 (2009).
Mula, J., Lee, J.D., Liu, F., Yang, L. & Peterson, C.A. Automated image analysis of skeletal muscle fiber cross-sectional area. J. Appl. Physiol. 114, 148–155 (2013).
Liu, F. et al. Automated fiber-type-specific cross-sectional area assessment and myonuclei counting in skeletal muscle. J. Appl. Physiol. 115, 1714–1724 (2013).
Mendias, C.L., Kayupov, E., Bradley, J.R., Brooks, S.V. & Claflin, D.R. Decreased specific force and power production of muscle fibers from myostatin-deficient mice are associated with a suppression of protein degradation. J. Appl. Physiol. 111, 185–191 (2011).