FNDC5 and sarcopenia: Beyond inflammation and oxidative stress, we found that circulating biomarkers related to other physiological functions involved in the causative cascade of sarcopenia including muscle metabolism (creatinine, irisin), steroid hormone regulation (DHEA-S, cortisol), insulin signaling (c-peptide, insulin, leptin), and tissue oxygenation (haemoglobin, haematocrit, red blood cell) are linked to sarcopenia baseline status and sarcopenia reduction post-intervention.