Myasthenia gravis: The aging trend is becoming more pronounced in our country, and myasthenia gravis, an aging syndrome associated with various adverse health outcomes, has been extensively studied in recent years. Myasthenia gravis manifests as an age-related decrease in skeletal muscle mass, strength and function. I. Definition of sarcopenia Sarcopenia, also known as sarcopenia, is an age-related geriatric syndrome characterized by progressive loss of muscle mass, strength, and function and is a strong factor in frailty, disability, and death in older adults. II. Epidemiology Sarcopenia affects 5% to 13% of 60- to 70-year-olds and up to 50% of those in their 80s, and the prevalence of sarcopenia in the general elderly population in Asia is 4.1% to 11.5%. Classification Primary sarcopenia: There is no obvious cause other than age. Secondary oligomyositis: both physical activity-related (long-term bed rest, sedentary lifestyle, etc.) and disease-related (heart, lung, liver and other organ failure, inflammatory diseases, or endocrine diseases that cause a decrease in skeletal muscle mass and function). Nutrition-related oligomyositis: mainly caused by insufficient energy/protein intake, gastrointestinal dysfunction, impaired digestion and absorption, or anorexia due to medications. IV. Clinical symptoms Hypotonia: Studies have shown that hypotonia exists in patients with sarcopenia in different limbs and under different loads. Decreased muscle mass: The main cause of muscle reduction is the decrease in the number of type I and II muscle fibers and the decrease in the volume of myocytes, in which the decrease in type II muscle fibers is the main cause. V. Diagnosis: 1. decreased muscle mass. 2. decreased muscle strength. 3. decreased muscle function. The diagnosis can be made by satisfying Article 1 with 2 and (or 3). VI. Possible mechanisms Aging changes in the body: In the process of human aging, the function and performance of the musculo-neural system decreases significantly, and even healthy elderly people inevitably experience a decrease in skeletal muscle mass and muscle strength. Lifestyle changes: With aging, physical activity levels decrease, physiological system function adaptively decreases, and exercise capacity is further reduced. This leads to a vicious cycle. Alterations in neurological factors: Some studies have shown alterations 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, the examination pathway of sarcopenia 1, through the measurement of grip strength, muscle mass and gait speed comprehensive assessment of sarcopenia: the current internationally recognized diagnostic criteria of sarcopenia, the main diagnostic indicators include muscle mass (muscle mass measurement), grip strength (muscle strength measurement) and gait speed (muscle function measurement). Measurement of muscle mass: The muscle mass of different parts of the body is measured by X-ray bone densitometry (DXA), CT, magnetic resonance imaging (MRI) and other equipment. If DXA can be used to determine muscle mass, the relative skeletal muscle mass index can be calculated. Measurement of muscle strength: hand grip strength is convenient and easy to measure and can generally reflect the muscle strength of other parts, so the measurement of hand grip strength is recommended. Measurements of muscle function: step speed is a good objective index, convenient to carry out and easy to be accepted by the subjects, so the daily step speed method is recommended to assess muscle function, such as the 6-meter walk test. The L3 muscle index is defined as the cross-sectional area of the muscles in the L3 plane. Eight, the dangers of sarcopenia sarcopenia can interact with chronic diseases such as chronic obstructive pulmonary disease, chronic heart failure, diabetes mellitus and osteoporosis in the elderly; it can cause patients with motor function, dysfunction, and lead to increased risk of falls, fractures, and even loss of independent living ability or the need for long-term care, increasing the risk of death. A Japanese study of elderly inpatients showed that sarcopenia can lead to a decline in swallowing function in the elderly and is an independent risk factor for dysphagia in elderly inpatients; it may be associated with a decline in tongue pressure and open jaw motor function in the elderly. IX. Treatment and prevention 1. Increase resistance exercise: Resistance exercise has the most evidence to increase muscle strength and maintain muscle volume. 20 minutes to 30 minutes is recommended more than 3 times a week, and due to individual differences, it is best to develop an individualized exercise program. 2, increase protein intake: protein accounts for 20% of muscle weight and is an important raw material for muscle synthesis. Older people consume 1.0g/kg to 1.5g/kg of protein per day. 3, increase vitamin D intake: some studies show that in people with low vitamin D levels, increasing vitamin D can effectively enhance the strength of hip flexors. The elderly can supplement vitamin D through sun exposure, food intake or taking vitamins as prescribed by the doctor. 4, actively control chronic diseases: chronic diseases are often accompanied by inflammatory reactions and enhanced protein catabolism. Effective control of chronic diseases can reduce the inflammatory response of the body, which has an important role in maintaining muscle capacity, muscle strength and muscle function. 5, drug treatment: insulin (INS) promotes the synthesis of fast muscle fiber protein; growth hormone (GH) affects the metabolism of muscle protein to play a muscle nutrition role; adrenocorticotropic hormone (ACTH) has a motor neuron nutrition role; sex hormones (testosterone, estrogen, etc.) significantly promote muscle synthesis.