Hypomyositis: The aging trend in China is becoming more and more obvious, and hypomyositis, as a geriatric syndrome associated with various adverse health outcomes, has been extensively studied in recent years. Myasthenia gravis is characterized by age-related reductions in skeletal muscle mass, strength and function. I. Definition of sarcopeniaSarcopenia, also known as sarcopenia, is an age-related geriatric syndrome characterized by progressive loss of muscle mass, strength, and function, and is a strong contributor to debility, disability, and death in older adults. Epidemiology Oligomyositis affects 5% to 13% of 60-70 year olds and up to 50% of 80+ year olds, and the prevalence of oligomyositis in the general elderly population in Asia ranges from 4.1% to 11.5%. Classification of primary oligomyosarcoma: except for age, there is no other obvious cause of the disease. Secondary oligomyosarcoma: It includes physical activity-related (long-term bed-ridden, sedentary lifestyle) and disease-related (heart, lung, liver and other organ failure, inflammatory diseases, or endocrine diseases, etc. caused by the decline in skeletal muscle mass and function). Nutrition-related hypomuscular disorder: mainly caused by insufficient energy/protein intake, gastrointestinal dysfunction, digestive and absorption disorders, or anorexia caused by medication. Fourth, clinical symptoms of muscle weakness: studies show that patients with sarcopenia have a loss of muscle strength in different limbs and under different loads. Decrease in muscle mass: the main cause of muscle loss is the decrease in the number of type I and II muscle fibers as well as the decrease in the volume of myocytes, with the decrease in type II muscle fibers being the main cause. V. Diagnosis: 1. Decrease in muscle mass. 2. Decrease in muscle strength. 3. Decrease in muscle function. 4. Diagnosis can be made if the first one is satisfied and the second and (or third) are satisfied at the same time. VI. Possible Mechanisms Aging changes in the body: In the process of human aging, the function and performance of the musculo-neurological system decreases significantly, and even healthy elderly people inevitably experience a decrease in skeletal muscle mass and hypomuscular strength. Lifestyle changes: with aging, the level of physical activity decreases, the physiological system functions adaptively, and exercise capacity is further reduced. This leads to a vicious cycle. Changes in neurological factors: Some studies have shown changes in the innervation of aging skeletal muscle, including denervation and restoration of innervation, motor unit remodeling and loss. The remodeling of motor units in aging skeletal muscle leads to changes in the composition of skeletal muscle fiber types. Seven, myasthenia gravis examination pathway 1, through the measurement of grip strength, muscle mass and step speed comprehensive assessment of myasthenia gravis: at present the international generally recognized diagnostic criteria of myasthenia gravis, its main diagnostic indicators include muscle mass (muscle mass measurement), grip strength (muscle strength measurement) and step speed (muscle function measurement). Measurement of muscle mass: Measurement of muscle mass in different parts of the body by X-ray bone densitometer (DXA), CT, magnetic resonance imaging (MRI) and other equipment. For example, muscle mass can be measured by DXA and relative skeletal muscle mass index can be calculated. Measurement of muscle strength: Handgrip strength is convenient and easy to measure and can generally reflect the muscle strength of other parts of the body, so it is recommended to measure handgrip strength. Measurement of muscle function: Step speed is a good objective index, convenient to carry out and easy to be accepted by the subjects, so it is recommended that the daily step speed method to assess muscle function, such as the 6-meter walking test. 2, through the CT measurement of lumbar psoas cross-sectional area of the third lumbar vertebrae (L3) planes, through the measurement of lumbar psoas cross-sectional area of the total amount of human body tissues in the general population. L3 muscle index is defined as the cross-sectional area of the muscles of the L3 planes. L3 muscle index is defined as the cross-sectional area of the L3 plane muscle. Eight, the danger of myasthenia gravis myasthenia gravis can interact with chronic diseases such as chronic obstructive pulmonary disease, chronic heart failure, diabetes mellitus and osteoporosis in the elderly; it can cause the patient’s motor function, dysfunction, and lead to an increased risk of falls, fractures, and even the loss of the ability to live independently or the need for long-term care, and increase the risk of death. A Japanese study of elderly hospitalized patients showed that sarcopenia can lead to a decline in swallowing function in the elderly, and is an independent risk factor for dysphagia in elderly hospitalized patients; it may be related to the decline in tongue pressure and jaw opening motor function in the elderly. Nine, treatment and prevention 1, increase resistance exercise: resistance exercise has the most evidence, can increase muscle strength, maintain muscle capacity, it is recommended that more than 3 times a week, each 20 minutes to 30 minutes appropriate, due to individual differences, it is best to develop a personalized exercise program. 2, increase protein intake: protein accounts for 20% of the weight of the muscle, it is an important raw material for the synthesis of muscle. Elderly people should consume 1.0g/kg to 1.5g/kg of protein per day.3. Increase Vitamin D intake: Studies have shown that in people with low levels of Vitamin D, increasing Vitamin D can effectively enhance the strength of the hip flexors. Elderly people can supplement vitamin D through sun exposure, food intake or taking vitamins as prescribed by the doctor.4. Actively controlling chronic diseases: Chronic diseases are often accompanied by inflammatory reactions and enhanced protein catabolism. Effective control of chronic diseases can reduce the body’s inflammatory response, which is important for maintaining muscle volume, muscle strength and muscle function. 5, drug therapy: insulin (INS) promotes protein synthesis in fast muscle fibers; growth hormone (GH) affects muscle protein metabolism to play a muscular trophic effect; adrenocorticotropic hormone (ACTH) has a trophic effect on motor neurons; sex hormones (testosterone, estrogen, etc.) significantly promote the development of muscle nutrition. (ACTH) has a trophic effect on motor neurons; sex hormones (testosterone, estrogen, etc.) significantly promote muscle synthesis.