There is no doubt that a lot of things would change in our bodies as we grow older. The most visible changes occur in the appearance of our skin. But a lot goes on beneath the skin too. Progressive changes occur in every system of our bodies as we advance in age. The muscular system is not left out. So, what are the effects of aging on the muscular system? How does aging change the structure and function of our muscles? Primarily, over time as you begin to age, you will lose a good measure of muscle mass as well as strength. This could have profound effects on both health and performance.
The decline in muscle mass and function that occurs with age is called Sarcopenia. This name is a combination of two Greek words, ‘sarcos’ and ‘penia’. In Greek, sarcos means flesh, while penia means loss. But then, in modern medical terms, its meaning also included the loss of power and muscle strength, as well as a reduction in function. Sarcopenia is a normal occurrence with an increase in age. It is one of the major reasons why older people are frail. You will agree that frailty is one of the major fears of people about old age.
What Are the Effects of Aging on the Muscular System?
There are quite a few changes that occur in your muscular system with age. But let’s start with the changes that affect gross muscle tissues. These changes in gross muscle tissues include the following:
1. Reduction in muscle mass
Muscular changes with old age start from the loss of muscle mass. And since lean muscle mass makes up about half the total of your body weight, you would also lose weight when your muscle mass decreases.
Do you know that you may have lost as much as 25 percent of your muscle mass by the age of 75 years? By the time you are 75 years old, most of your muscle mass would have been replaced with an increase in fat mass.
Even from early adulthoods, the muscle mass of your lower limbs would have started reducing gradually. But by the time you hit 50 years of age, the reduction begins to happen at a faster rate.
The major decrease is seen in structures that aid contraction (called contractile structures). On the other hand, there is usually an increase in non-contractile structures like connective tissues and fat.
2. Reduction in muscle strength
It may surprise you to know that from the time you are about 25 years old, the number of fibers in your muscles would start decreasing slowly. This progresses at a more pronounced rate when you grow much older.
So then, your muscle mass would not only reduce, but the number of fibers in your muscles would also reduce as you age. Meanwhile, the reduction in muscle mass may be a resultant effect of this reduction in muscle fibers.
As muscle fibers reduce in number as muscle mass reduces too, strength would also reduce. As such, you would not be able to exercise much or carry out normal daily activities.
Changes That Occur in Muscle Fiber as You Age
Aside from the reduction in the number of muscle fibers that lead to a reduction in strength, a few other changes affect muscle fibers. They are as follows:
1. Changes That Affect the Size of Muscle Fiber
Have you ever wondered why aged people often fall? They usually fall because the strength of their muscles and ability to balance has reduced. These reductions occur as a result of muscle aging.
There are different types of muscle fibers. Types II (A and B) muscle fibers usually reduce as we age. These reductions occur in their total number, area percentage, and average fiber area.
Type I fibers, on the other hand, would increase both in number and cross-sectional area. However, they do not increase in size.
Due to the reductions that happen in Type II (A and B) fibers, they usually appear flatter and smaller, thus reducing in quality. As muscle quality deteriorates, balancing coordination would also deteriorate.
However, the reduction in the total number of fibers has a greater effect than the changes that affect individual fibers. However, since type II (fast-twitch) muscle fibers are responsible for force generation. Aged people may have problems in this area.
2. Changes That Affect the Size and Number of Motor Units
Nerves control the activity of muscles at the fiber level. These nerves are called motor neurons. Most experts agree that muscle fibers are usually lost on older people due to the loss of motor neurons.
One of the normal cycles of life is the denervation and re-innervation of muscle fiber. This occurs all through an individual’s lifespan. The problem in old age is that denervation seems to occur at a faster rate than re-innervation.
By the time you are 60 years old, you would likely have only about three-quarts to half the motor neurons you had at the age of 20. What then happens to the de-innervated muscle fibers? They would most likely just die off.
Some fast-twitch fibers do not die off, though. They get re-innervated by slow-twitch neurons. This would make them act like slow-twitch fibers even though they are not.
Effects of Sarcopenia on Muscle Function
There is virtually no system in your body that has nothing to do with the muscular system in one way or the other. This means that anything that generally affects the muscular system has wide-spread effects. It would have a great impact on how you function in all the activities of your daily living.
Sarcopenia contributes majorly to:
- A reduction in gait speed
- An increased number of falls due to the reduced level of balance
- Fractures in old age (as a result of more falls)
What are the effects of aging on the muscular system? They cause changes in both gross muscle tissue and muscle fibers. These changes can negatively affect your health and performance. But then, they can be reversed by frequent resistant training, a well-balanced healthy diet, and taking dietary supplements as needed.