Since the impact of Fgf2 germ-line knockout on age-related muscle function or skeletal muscle phenotype has not been reported, we examined whether aging is associated with changes in Fgf2 expression in skeletal muscle, and whether disruption of the Fgf2 gene in mice results in exacerbation of impaired exercise tolerance and muscle strength and sarcopenia in skeletal muscle with age. The gene discussed is FGF2; the disease is sarcopenia.