FNDC5 and osteoarthritis, knee: Previous meta-analyses show that low HGS is associated with higher risk of knee osteoarthritis, heart failure complications, disability, cognitive and mobility decline in older adults, and increased mortality across healthy, elderly and clinical populations.48, 54 This may relate to the endocrine role of muscle tissue, which secretes myokines such as myostatin, irisin and IL-6.55