Disease Description (Causes and Symptoms)
- Definition: Sarcopenia is a condition in which the amount of skeletal muscle (muscle mass), muscle strength, and muscle function all decrease due to aging or disease, resulting in reduced ability to perform daily activities and increased health risks.
- Causes and pathophysiology: Multiple factors act together, including age-related decreases in hormones (sex hormones, growth hormone), insufficient protein intake (especially essential amino acids and leucine), reduced physical activity (especially resistance exercise), chronic inflammation and chronic diseases (diabetes, chronic kidney disease, chronic lung disease, etc.), degeneration of neuromuscular connections, and the effects of medications (such as steroids). This leads to muscle fiber atrophy, decreased muscle protein synthesis, and abnormalities in metabolic and hormonal regulation.
- Main symptoms: Decreased muscle strength (especially grip strength and lower-extremity strength), slower walking (reduced walking speed), fatigue and reduced exercise tolerance, difficulty performing daily activities, and increased risk of falls and fractures.
Treatment Methods
- Non-pharmacological treatment (basic treatment)
- Resistance (strength) exercise: Strengthening exercises at least 2–3 times per week, centered on progressive overload and multi-joint exercises, are essential. Walking and balance training should be performed concurrently to prevent falls.
- Aerobic exercise: Approximately 150 minutes per week of moderate-intensity aerobic exercise is recommended to improve cardiorespiratory fitness and metabolism, when possible.
- Nutritional therapy: The generally recommended total protein intake is 1.0–1.2 g/kg/day for older adults and 1.2–1.5 g/kg/day in cases of sarcopenia or acute/chronic disease, taking kidney function into consideration. At least 25–30 g of high-quality protein (including leucine) per meal is recommended; whey protein or essential amino acid (EAA) supplementation may be considered when necessary. Supplementation is recommended in cases of vitamin D deficiency.
- Multidisciplinary approach: Physical therapy (exercise prescription), consultation with a dietitian, optimization of medications and chronic diseases, fall-risk assessment, and environmental modifications.
- Pharmacological approaches
- There are currently limited medications specifically approved for sarcopenia. Hormones (such as testosterone), selective androgen receptor modulators (SARMs), and myostatin inhibitors are either still in the research stage or have limited use because of side effects and indication-related issues.
- As adjunctive measures, vitamin D supplementation in cases of deficiency and protein supplements or HMB (β-hydroxy β-methylbutyrate) have been reported in some studies to improve muscle mass and function.
- Surgery/procedures
- There is no surgical treatment for sarcopenia itself. Appropriate medical or surgical treatment for underlying diseases (for example, spinal diseases causing pain) may help restore function.
- Precautions (during treatment)
- If reduced kidney function, such as chronic kidney disease (especially before dialysis), is present when a high-protein diet is recommended, the recommended protein intake should be adjusted according to kidney status, and a nephrologist should be consulted.
- Exercise should be performed gradually, taking the individual’s cardiovascular and joint conditions into consideration. If cardiovascular or respiratory disease is also present, exercise should be performed after medical evaluation.
- Medication supplementation (such as hormones) requires carefully considered indications and monitoring because of the risk of side effects, including blood clots and prostate problems.
Checkpoints Before an Outpatient Visit (Items to Bring and Sample Questions)
- Items/test records to bring
- A list of medications and supplements currently being taken, including dosage and duration of use
- Recent records of weight changes (weight and height) and a dietary (protein intake) diary, if possible for 3 days
- Fall history (whether any falls occurred in the past year) and records of changes in walking (speed and distance)
- Previous test results: DXA (skeletal muscle mass/bone mineral density), BIA, CT/MRI muscle imaging, and blood tests (creatinine, blood glucose, TSH, vitamin D, etc.)
- If available, bring records of functional tests (grip strength, walking speed, SPPB, etc.)
- Key information to provide to healthcare professionals during the outpatient visit
- When changes in muscle strength or walking began and how they have progressed or worsened
- Whether there have been changes in the ability to perform daily activities (ADL/IADL)
- Exercise habits and recent changes in activity level
- Sample questions (for patients to check themselves)
- "How many kilograms have you lost recently?"
- "Have you experienced any falls recently? If so, what was the situation?"
- "How much protein (meat, fish, eggs, dairy products, etc.) do you consume per day?"
Examples of General Questions to Ask the Doctor
- "What do you think is the cause of my sarcopenia? Are there any additional tests I should have?"
- "What type of exercise program (type, frequency, and intensity) do you recommend? Should I receive physical therapy or rehabilitation?"
- "What is your recommendation regarding the recommended protein intake and the use of supplements (whey protein, EAA, HMB, etc.)? How should this be adjusted if I have kidney problems?"
- "What is the prognosis, and in what situations is function likely to recover substantially or worsen?"
Examples of Disease-Specific Questions
- "If grip strength or walking speed measurement results are available, what criteria do my current values meet (for example, the EWGSOP2 criteria)?"
- "What home environmental improvements and assistive devices (such as a cane or walker) do you recommend to reduce the risk of falls?"
Additional guidance: The diagnosis and treatment plan should be individualized based on factors such as the person’s age, comorbidities, kidney function, and activity level. When necessary, accurate diagnosis and follow-up are recommended through strength and functional assessments (grip strength, walking speed, DXA/BIA, etc.).