Moreover, irisin increased bone mass in healthy mice [22] and, in hindlimb unloaded mice, a well-known osteo-sarcopenic mouse model of disuse-induced osteoporosis and muscle atrophy, irisin promotes osteogenesis, increases osteocyte viability, and prevents disuse-induced loss of bone and muscle mass [17,23]. The gene discussed is FNDC5; the disease is Atrophy.