Muscular atrophy (loss of muscle mass)
Muscular atrophy is the thinning and weakening (atrophy) of muscles. Everyone experiences a natural decrease in muscle mass and a slower metabolism as they age. This is partly due to hormonal changes and reduced physical activity.
Muscular atrophy can also result from prolonged inactivity of our body (coma, paralysis) or a limb (cast), from a nerve control problem (such as in Parkinson’s disease) or from a protein deficiency (cancer, starvation, etc.).
Sarcopenia is an age-related decline in muscle mass (diameter) and a loss of muscle strength. The loss of skeletal muscle begins around the age of 30, increases with age, and can be worsened by illness, malnutrition and inactivity. A key consequence of muscle mass loss is the reduction of muscle strength. Muscle strength is therefore the primary parameter of sarcopenia.
Frailty is a multidimensional geriatric syndrome whose pathogenesis includes both physical and social aspects and is characterized by a cumulative decline in various physiological processes and functions. Sarcopenia is a condition that is part of this geriatric syndrome.
Muscular atrophy
Muscular atrophy can occur at any age.
The speed or progression of muscular atrophy, as well as the possibility and duration of recovery or healing, depent on:
- overall physical health
- the type or form of muscular atrophy
- and, in connection with these, the underlying cause that led to the muscular atrophy
Muscular atrophy resulting from physical, mechanical trauma such as bone fracture is temporary and reversible in healthy individuals in good condition.
However, if there are underlying disease conditions, unhealthy and/or poor eating habits, difficult living conditions or malnutrition, then “healing” or recovery is not always possible. In cases of prolonged atrophy, sarcopenia and advanced age, cell regeneration is very slow so recovery can take a long time.
Under certain or special circumstances, for example when a (degenerative) disease is the root of the cause of muscular atrophy, recovery is no longer possible and the loss of muscle mass is irreversible.
Prevalence of Sarcopenia
Sarcopenia occurs in 10 to 50 percent of people aged 65 and older, and increases rapidly with age. As many as 31 percent of women and 52 percent of men over 80 suffer from sarcopenia. They retain only about 50 percent of their original muscle tissue.
Sarcopenia affects people living at home, elderly residents in care homes, and hospital patients alike.
Consequences of Sarcopenia
The consequences of sarcopenia in older adults are serious and have a major impact on daily functioning: the risk of falls and fractures is increased, the ability to perform daily activities is reduced, there is an association with a higher incidence of heart disease, respiratory conditions and cognitive disorders, and it leads to mobility impairments and reduced quality of life, loss of independence, higher risk of death and increased healthcare costs (nutrition and exercise).
People with sarcopenia are two to three times more likely to break a hip, leg, arm, wrist or collarbone in a fall.
Treatment of muscular atrophy and sarcopenia
Since the loss of muscle mass is a natural process, sarcopenia cannot always be prevented. However, early detection and treatment can help reduce the decline in muscle mass and muscle function.
The Belgian Society for Gerontology and Geriatrics (BSGG) published guidelines in 2020 for the prevention and treatment of sarcopenia. Based on systematic review of the medical literature, they made recommendations for the treatment of sarcopenia in the areas of exercise, nutrition and pharmacology (source: nutrition and exercise).
Exercise – resistance training
Since sarcopenia affects all skeletal muscles in the body, it is recommended to train the large muscle groups using a whole-body approach. There is evidence for a positive and significant effect of resistance training on muscle mass, muscle strength and physical performance. For maximum strength gains, a high-intensity resistance training program is recommended (i.e., 80% 1RM). Light resistance training (≤50% 1RM) can also be sufficient to increase strength. The following training parameters are recommended: 1-4 sets of 8-15 repetitions during 2-3 training sessions per week.
The basis is the Dutch physical activity guideline for adults and older people:
- Exercise is good, moving more is better.
- Do at least 150 minutes per week of moderate-intensity activity, such as walking and cycling, spread over several days.
- Do muscle- and bone-strengthening activities at least twice a week; for older adults, combine these with balance exercises.
- And avoid prolonged sitting.
Nutrition – protein
In addition to strength training, nutrition is a crucial factor in building muscle, especially as we age.
Adequate protein intake combined with resistance training is recommended to increase muscle mass and strength. This is particularly advised for people with obesity and should be maintained for at least 24 weeks to achieve optimal results. Additionally, there is evidence (grade 3) supporting leucine supplementation, as it has a significant effect on muscle mass in people with sarcopenia.
A varied diet following the guidelines forms the basis for adequate protein intake.
The most recent guidelines further support a protein intake for older adults that is higher than the recommended daily allowance for healthy adults, namely not 0.8 g/kg body weight/day, but 1.0-1.2 kg protein/kg body weight for healthy older adults, 1.2-1.5 g/kg body weight for vulnerable older adults and 1.5-2.0 g/kg body weight for severely ill or malnourished older adults, preferably with 25-30 g protein per meal .
This quickly amounts to a protein requirement of about 80 g per day. Frail, ill and malnourished older adults eat only about a quarter of what healthy adults eat. Simply eating more protein-rich foods to reach this amount of protein, which is necessary for muscle building, is not a solution. Meals must be enriched with fast-absorbing proteins during the day and slow-absorbing proteins at night to maintain the muscle mass built.