Sarcopenia (Age-Related Muscle Loss)

What happens in sarcopenia

Muscle is constantly broken down and rebuilt. With aging, the balance shifts toward breakdown. Contributing changes include:

• loss of the nerve cells that drive muscle fibers, especially fast-twitch fibers needed for power
• reduced response of muscle to protein and exercise ("anabolic resistance")
• lower levels of hormones such as testosterone, growth hormone and IGF-1
• chronic low-grade inflammation
• fat infiltrating muscle, reducing its quality

Muscle strength tends to decline faster than muscle size, which is why strength is now central to the definition.

Causes and risk factors

Primary (age-related)

Aging itself, beginning gradually from middle age.

Secondary sarcopenia

• Inactivity: bed rest, sedentary lifestyle, hospital stays. Older adults can lose a significant amount of leg muscle strength within 1 to 2 weeks of bed rest.
• Poor nutrition: low protein and calorie intake, malnutrition
• Chronic diseases: heart failure, COPD, chronic kidney disease, diabetes, cancer, liver disease and inflammatory conditions
• Hormonal changes: low testosterone, menopause, thyroid problems
• Medicines: long-term steroids
• Obesity: sarcopenic obesity, low muscle combined with excess fat, carries combined risks
• Rapid weight loss without strength training

Signs and symptoms

• weakness, especially in the legs and grip
• difficulty getting up from a chair or the floor without using your arms
• slower walking speed
• trouble climbing stairs or carrying bags
• poor balance and falls
• thinner arms and legs
• tiredness and reduced stamina

Diagnosis

The EWGSOP2 approach uses three steps:

1. Find: screening questionnaires such as SARC-F (asking about strength, walking, rising from a chair, climbing stairs and falls).
2. Assess strength: - grip strength with a dynamometer: low if under 27 kg in men or 16 kg in women - chair stand test: taking more than 15 seconds to stand up 5 times without using the arms
3. Confirm with low muscle quantity measured by DXA, bioimpedance, CT or MRI.

Severity is graded by physical performance, such as walking speed of 0.8 m/s or slower, or the Short Physical Performance Battery.

A doctor will also look for treatable contributors with blood tests (vitamin D, thyroid function, kidney function, testosterone in men) and review medicines and diet.

Treatment

Resistance exercise

Progressive resistance training is the most effective treatment:

• 2 to 3 sessions a week, working all major muscle groups
• start with body weight, resistance bands or light weights, then progress
• examples: sit-to-stands, wall push-ups, step-ups, calf raises, seated rows, leg press
• add balance training (tai chi, standing on one leg near support) and walking for endurance

Strength gains are possible even in people in their 90s. Supervised programs with a physical therapist help people with health conditions or a history of falls.

Nutrition

• protein: expert groups suggest older adults aim for about 1.0 to 1.2 g of protein per kg of body weight a day (more with illness), spread across meals, unless kidney disease limits intake
• include protein-rich foods at each meal: eggs, dairy, fish, poultry, beans, lentils and soy
• vitamin D supplementation if levels are low
• adequate calories to avoid weight loss

Medical management

• treat underlying conditions such as heart failure, COPD and diabetes
• review medicines that contribute to weakness or falls
• testosterone replacement only for men with confirmed low testosterone, after discussing risks and benefits
• there are currently no medicines approved specifically for sarcopenia

Complications

• falls and fractures, especially with osteoporosis
• frailty and disability
• loss of independence and need for care
• longer hospital stays and slower recovery from illness and surgery
• higher risk of death

Prevention

• stay physically active throughout life, including strength training at least twice a week
• eat enough protein, especially in older age
• avoid long periods of inactivity; get moving quickly after illness or surgery
• maintain a healthy weight; combine any weight loss with strength exercise
• do not smoke and limit alcohol

Frequently asked questions

What is sarcopenia?

Sarcopenia is the loss of muscle strength, mass and function that comes with aging. It makes everyday tasks harder and increases the risk of falls, fractures, frailty and loss of independence. It is common after 60 and treatable.

What are the first signs of sarcopenia?

Early signs include weaker grip, needing your arms to stand up from a chair, slower walking, difficulty climbing stairs and tiring more easily. Some people notice thinner arms and legs or more frequent stumbles and falls.

Can sarcopenia be reversed?

Yes, to a significant degree. Progressive resistance training combined with enough protein can rebuild muscle strength and improve function at any age, including in people in their 80s and 90s. Results usually appear within 8 to 12 weeks.

What is the best exercise for sarcopenia?

Resistance (strength) training is the most effective, 2 to 3 times a week, working the legs, hips, back, chest and arms. Sit-to-stands, step-ups, resistance band rows and leg presses are good examples. Adding balance and walking exercises reduces falls.

How much protein do older adults need to prevent muscle loss?

Many experts recommend older adults aim for about 1.0 to 1.2 g of protein per kilogram of body weight daily, spread over meals. People with kidney disease should ask their doctor before increasing protein intake.