Exercising Isn't the Same as Being Strong: An Exercise Prescription for Sarcopenia

Older-adult population growth and a country’s dependency ratio, and especially the old-age dependency ratio, have begun to change noticeably in recent years. In Taiwan the total dependency ratio reached its lowest point of 34.7 people in 2012, rose to 40.1 people in 2020, and is projected to increase to 102.0 people by 2070, roughly a 2.5-fold rise.

• Total dependency ratio = (young population + older population) ÷ working-age population × 100 = old-age dependency ratio + youth dependency ratio
• Youth dependency ratio = young population ÷ working-age population × 100
• Old-age dependency ratio = older population ÷ working-age population × 100

Sarcopenia has drawn attention in recent years, though related research goes back to the 1980s, and diagnostic and intervention guidelines have gradually matured. Sarcopenia is a condition that can potentially be prevented, improved, and even reversed. Spending a little time each day on suitable exercise, and sticking with it, can lead to better strength. Unfortunately, few older adults are willing to take part in training, perhaps only about 10%. Reasons include past injuries, pain, too many other chronic conditions, and a fear of exercising because of aging. In reality, once someone is willing to take the first step, a lot can change.

After age 40, muscle mass declines by about 8% per decade, and after age 70 it declines by about 15% per decade. Loss of muscle mass, decline in muscle function, and reduced hormone secretion are all consequences of aging, which in turn affect movement function, protein synthesis and metabolism, and the body’s mobility.

Causes of sarcopenia

The main causes of sarcopenia include aging, reduced activity due to illness, and malnutrition; others include hormonal changes, reduced blood flow to muscle, systemic inflammation, mitochondrial dysfunction, and neuropathy. Aging is the most important cause. Everyone ages at a different rate, but the benefits of exercise help across different degrees of aging:

• Can slow the progression of decline in exercise capacity
• Improves body composition (less fat, more muscle mass)
• Helps manage chronic disease
• Promotes psychological and cognitive well-being
• Reduces the risk of physical disability

Treating sarcopenia

Treatment mainly has two parts: exercise and nutrition. Although some drugs, such as testosterone, certain androgens, growth hormone, and insulin-like growth factor, have been studied and may increase muscle mass, their side effects are too large for routine use. The genuinely useful and root-addressing approaches are still exercise and nutrition.

The body’s ability to produce force quickly is called power. Recent research indicates that with increasing age, the loss of power exceeds the loss of strength, which is related to type II muscle fibers. Insufficient power carries a higher risk of falls. Through resistance training, not only strength but also power can improve, and the relevant resistance training ideally includes both single-joint and multi-joint movements.

Current research strongly recommends progressive resistance training as the first-line therapy. Resistance training can improve muscle function, increase skeletal muscle mass, and enhance physical function. It includes exercises that improve muscle strength and endurance by working against force generated by body weight, gravity, elastic bands, weightlifting barbells, or dumbbells; various fitness machines can also be used for resistance training.

In studies where resistance training was performed 3 times per week for 16 weeks and evaluated with DEXA and CT, functional assessments, grip strength, gait speed, and isometric strength improved significantly, while muscle growth factors increased.

Beyond resistance training, aerobic exercise can improve cardiovascular function in older adults, and stretching and agility training can improve balance. All are essential to the exercise prescription. Aerobic exercise significantly affects skeletal muscle, driving ATP production in mitochondria and thereby enhancing metabolic regulation, aerobic capacity, and cardiovascular health.

Effective aerobic training is characterized by sufficient intensity (70–80% heart rate reserve), duration (30–45 minutes), and frequency (4–5 days per week). In contrast to resistance training, which focuses on muscle enlargement, it provides high-volume, low-load exercise that can still markedly activate muscle and promote overall muscle function and growth. Aerobic exercise involves the repeated use of major muscle groups and has been shown to enhance mitochondrial activity and capillary density, thereby improving oxygen utilization and muscular endurance.

Previous research supports that exercise can improve bone density, body fat and muscle ratio, blood glucose and lipid status, and blood pressure. Aerobic and strength training each have their strengths: resistance training has advantages for bone density and increasing muscle mass, while aerobic training has more research support for blood pressure control, fat reduction, and improving endurance.

Compared with younger people, using the rating of perceived exertion (RPE) scale to monitor exercise level may be more suitable for older adults. Exercise prescriptions for older adults need to consider different points than for younger people: building a safe and effective exercise plan, providing appropriate social and family support, reducing worry about injury and pain, and even breaking down society’s stereotypes about certain forms of exercise. All of these need careful and repeated consideration when designing an exercise prescription and during the training itself.

Nutritional supplementation is also quite important in sarcopenia. Protein, essential amino acids, and vitamin D supplementation can significantly improve muscle mass and function in people with sarcopenia, and combining supplementation with resistance training produced greater benefit.

For the small number of patients who cannot undertake exercise and nutritional intervention, medication may be an option. A few studies have found that persistent inflammation and oxidative stress in the muscle of older adults can lead to muscle atrophy and reduce their capacity for physical activity.

Effective regulation of blood flow can help control the production of reactive oxygen species, improve muscle function, and reduce disease in older adults. In this context, the renin-angiotensin system acts as a vasodilator to regulate blood flow. Angiotensin-converting enzyme (ACE) inhibitors may have a possible effect on enhancing physical capacity in older adults with sarcopenia.

Other hormonal therapies and newer drugs, such as selective androgen receptor modulators (SARMs), and treatments that reduce inflammation, such as approaches targeting pro-inflammatory cytokines like TNF-α and IL-6, are also considered potential strategies against sarcopenia.

Summary

Treatment of sarcopenia focuses mainly on exercise and nutrition, with medication serving as a possible adjunct in specific situations. A multifaceted approach that combines exercise, nutrition, and appropriate medication, tailored to each person’s needs and abilities, can help older adults exercise with confidence and reduce the burden that sarcopenia may bring in the years ahead.

References

Mol Aspects Med. 2024 Jun:97:101270.

Further reading

• Rehab exercise — principles of rehabilitation, strength training, and exercise prescription
• Rehab exercise prescription — individualized exercise design for older adults and people with chronic disease