Skeletal muscle nicotinamide phosphoribosyltransferase (NAMPT) protein expression and mitochondrial content in metabolically distinct subjects. FH, nonobese sedentary subjects with or without family history of T2DM; AU, arbitrary units. A: NAMPT protein in skeletal muscle (means ± SD, n = 5, one-way ANOVA with Tukey's post hoc test, *P < 0.05, **P < 0.01 vs. Athletes). B: complex III protein in skeletal muscle (means ± SD, n = 5, one-way ANOVA with Tukey's post hoc test, **P < 0.01 vs. Athletes). C: mitochondrial DNA in skeletal muscle (means ± SD, n = 2–5, one-way ANOVA with Tukey's post hoc test, *P < 0.05, **P < 0.01 vs. Athletes).