Cross‐sectional studies revealed significant increases in muscle FNDC5 gene expression only in older (~55 years) active versus sedentary subjects (Timmons et al. 2012) and in heart failure patients (~67 years) with higher aerobic capacity, when subdivided into more fit (VO2 Peak ~17 mL/kg‐min) versus less fit (VO2 Peak ~11 mL/kg‐min) groups for statistical comparison (Lecker et al. 2012). The gene discussed is FNDC5; the disease is heart failure.