1) Disease Description (Causes and Symptoms)
- Definition summary: Sarcopenia is a condition in which muscle mass, muscle strength, and muscle function (physical function) decrease together, reducing the ability to perform activities of daily living and increasing the risk of falls and death.
- Main causes: Age-related hormonal changes (decreases in sex hormones, growth hormone, insulin, and IGF-1), inadequate protein intake (especially essential amino acids/leucine), insufficient physical activity (particularly resistance exercise), chronic inflammation (low-grade inflammation in older adults), chronic diseases (diabetes, chronic cardiopulmonary or kidney disease, cancer, etc.), malabsorption, medications (such as long-term steroids), and reductions in neuromuscular junctions and motor units.
- Key pathophysiology: Atrophy of muscle fibers (particularly type II fibers), reduction in motor units, decreased protein synthesis versus increased breakdown (including the ubiquitin–proteasome pathway), impaired mitochondrial function, and reductions in muscle strength and endurance due to intramuscular fat deposition and fibrosis.
- Typical symptoms: Slow walking speed, reduced grip strength, lower-extremity weakness/fatigue, difficulty performing activities of daily living (such as climbing stairs and standing up), and an increased risk of frequent falls and fractures.
2) Treatment Methods and Precautions
- Non-pharmacological treatment (basic treatment)
- Resistance strength training (2–3 times per week, following the principle of progressive overload): Strength exercises focusing on large muscle groups such as the quadriceps and gluteal muscles, aiming for 8–12 repetitions, are recommended.
- Combine with aerobic exercise (150 minutes of moderate-intensity or 75 minutes of vigorous-intensity exercise per week is recommended).
- Nutritional therapy: A total daily protein intake of 1.0–1.5 g/kg (adjusted according to health status and comorbidities) is recommended, with 20–40 g of high-quality protein (including leucine) per meal or snack. Vitamin D supplementation is recommended in cases of vitamin D deficiency (based on test results). Ensure adequate energy intake when calorie intake is insufficient.
- Occupational and physical therapy for restoring daily function (balance training and gait training).
- Fall prevention (environmental modifications, assistive devices, and osteoporosis management).
- Pharmacological/interventional treatment
- There is currently no approved specific drug for sarcopenia.
- In selected situations, hormone replacement (for example, considering treatment for low testosterone in men) or investigational drugs (potential therapeutic options such as SARMs and myostatin inhibitors) may be considered under the judgment of a specialist, but these are not standard treatments in general.
- Comorbidities and correction of causes
- Identify and correct chronic diseases (diabetes, thyroid or adrenal abnormalities, etc.), nutritional deficiencies, and medications (such as long-term steroids).
- Precautions (complications and self-management considerations)
- Be alert to a sharp decline in muscle strength after an acute illness or hospitalization (acute sarcopenia).
- Cardiovascular assessment is necessary before high-intensity exercise (when there is a history of cardiovascular disease).
- Excessive protein intake requires caution in cases of reduced kidney function (consult a specialist if there is a history of kidney disease).
- Osteoporosis testing and treatment are recommended in parallel to prevent falls and fractures.
3) Checklist Before an Outpatient Visit (Items to Bring and Example Questions)
- Items/data to bring
- A list of medications currently being taken (including prescription drugs, over-the-counter drugs, and nutritional supplements)
- Records of weight changes (over the past 6–12 months) and eating and protein-intake patterns (for example, the amount of protein consumed at one time)
- Daily activity level (stair climbing, walking distance, and whether assistance is needed) and a history of falls
- Previous test results (bone mineral density testing, DXA/BIA, and blood tests [creatinine, electrolytes, blood glucose, TSH, 25‑OH vitamin D, etc.])
- If possible, recent muscle strength (grip strength) and walking-speed measurements or results of functional tests (such as SPPB)
- Items to tell the doctor in advance during the outpatient visit
- Whether there has been rapid weight loss, decreased appetite, or difficulty swallowing (dysphagia)
- Whether there has been a recent hospitalization or prolonged bed rest
- Items for patients to record in advance as example questions
- Average daily walking time/exercise frequency and type
- Protein intake (approximate protein grams per meal) and whether supplements are being used
4) Examples of General Questions to Ask the Doctor
- What do you think is the cause of this condition? Are there any comorbidities?
- Based on what criteria, and to what extent, are my muscle status (muscle mass, muscle strength, and walking speed) abnormal? What is the prognosis?
- What exercise (frequency, intensity, and type) and nutrition (total protein amount and whether supplements are recommended) do you recommend?
- Could any medications or supplements I am currently taking affect sarcopenia? Should I stop or change any of them?
5) Examples of Disease-Specific Questions (1–2)
- What were the values for the diagnostic criteria for sarcopenia in my test results (for example, ASM/height^2, grip strength, and walking speed)? Which items are problematic?
- Could you tell me the specific exercise prescription recommended for my condition (number of sessions per week, sets and repetitions, and starting intensity) and my daily protein target in grams?