Scientists talked about the causes of age-related weakness
As a person ages, it may become more difficult for them to walk, climb stairs, and perform their usual daily activities. Sarcopenia is considered one of the reasons for such changes — loss of muscle mass, strength and physical abilities. However, decreased mobility may be related not only to the condition of the muscles, but also to changes in the nervous system that controls movement. About why strength and mobility decrease with age and what role the motor system plays in this is in the Izvestia material.
What is sarcopenia and how is it dangerous?
Sarcopenia is a significant loss of muscle mass, strength, and physical function associated with aging. It occurs in 29% of elderly people who live independently, and it is even more widespread in hospitals and institutions for the care of the elderly. The risk is also higher in people with several chronic diseases and physical weakness.
Sarcopenia contributes to the development of physical dependence and disability, as well as increases the risk of falls. They can lead to serious injury and loss of independence.
The authors of the new study believe that to understand the causes of age-related weakness, it is necessary to take into account not only changes in muscles, but also the work of the entire system that provides movement. The work was published in The Lancet Healthy Longevity (LHL) journal.
Why does muscle mass not explain the decrease in strength?
For a long time, sarcopenia was considered primarily as a muscle disease, and a decrease in strength was associated with a decrease in their mass. However, as the authors note, the loss of muscle tissue explains only a small part of the decrease in strength in the elderly.
Two people with the same amount of muscle tissue may have significantly different strength and mobility. In addition, medications and strategies to increase protein intake that help build muscle mass do not always lead to comparable improvements in daily physical performance.
At the same time, physical exercise can increase strength and improve mobility even without a noticeable increase in muscle mass. According to the authors, this indicates the need to study other mechanisms that affect movement.
How does the aging of the motor system affect movement
The authors propose to consider sarcopenia as a disease of the aging motor system. It includes the brain and spinal cord, nerves, their connections to muscles, and the muscles themselves.
With age, movements may be planned more slowly, nerve signals may be transmitted less reliably and with less intensity, and the sense of balance and body position in space may weaken. As a result, muscles can be preserved, but receive less effective neural commands.
The ability to develop effort quickly is especially important. For example, when getting up from a chair, not only muscle mass is important, but also the speed with which a person can perform the movement. The authors note that muscle power decreases earlier and faster with age than its mass, and largely depends on how effectively the nervous system uses muscle fibers.
How is it proposed to change the diagnosis and treatment
The diagnosis of sarcopenia already uses indicators that reflect a person's physical abilities, including grip strength, walking speed, and the ability to get up from a chair. According to the authors, these indicators better predict the risk of falls, disability, and death than just estimating muscle mass.
The researchers suggest additionally paying attention to the speed of getting up from a chair, stability during prolonged physical exertion, manual dexterity and gait changes when a person is talking at the same time. Special attention, in their opinion, requires weakness, which develops rapidly, affects different sides of the body differently or turns out to be a disproportionate loss of muscle mass.
In the future, the new approach may help to more accurately identify the causes of weakness in a particular person and develop more targeted treatment methods. However, this will require further research, verification of diagnostic tools, and clinical trials that take into account the condition of not only the muscles, but also the nervous system.
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