Diaphragm muscle sarcopenia is event by ~75% survival in mice. (A) Maximal isometric twitch force (Pt ) and maximal tetanic force (Po ), normalized to physiological cross-sectional area, of midcostal diaphragm muscle (DIAm) of mice across the lifespan (aged 6, 18 and 24 months). There is a significant (*) loss of force by 24 months of age but not between 6 and 18 months. Reprinted with permission from (Greising et al., 2015a). (B) Fiber cross-sectional area (CSA) of the DIAm of across the lifespan. There is a significant (*) loss of type IIx and/or IIb DIAm fiber CSA by 24 months of age. Data at 6 and 24 months of age adapted from (Greising et al., 2013), data at 18 months of age is pilot (n = 4). Mean ± SE.