Frailty is a clinically recognizable syndrome associated with aging and an increased risk of catastrophic decline in the health of elderly people. Muscles start degenerating with age which results in weakness, decreased energy, slowing, lower activity and severe unintended weight loss. Sarcopenia can be a cause of frailty. It is degenerative loss of skeletal muscle strength, quality and mass with age. The rate of muscle loss depends on several factors such as nutrition, exercise level and co-morbidities. Sarcopenia leads to reduced functional status and can cause significant disability from increased weakness. Muscle loss within this disease occurs due to changes in muscle synthesis signaling pathways. This book provides significant information of this discipline to help develop a good understanding of frailty and sarcopenia. Also included herein is a detailed explanation of the current issues and research on these medical conditions. This book is appropriate for students seeking detailed information in this area as well as for experts.