The optimal cutoff value for predicting sarcopenia was 118.0 ng/mL for irisin (sensitivity: 0.8; specificity: 0.5), 69.5 U/L for creatine kinase (sensitivity: 0.4; specificity: 0.8), 11.1 ng/mL for myostatin (sensitivity: 0.5; specificity: 0.8), 40.0 g/L for albumin (sensitivity: 0.2; specificity: 0.9), and 0.67 μM for coenzyme Q10 (sensitivity: 0.9; specificity: 0.2). Here, FNDC5 is linked to sarcopenia.