What is muscle strength and endurance?
It is very common for people with chronic obstructive pulmonary disease (COPD) to have symptoms that affect their muscles. These symptoms usually develop slowly over time as the disease progresses. The main symptoms are:1,2
- Lower muscle strength
- Lower muscle endurance
Together, these kinds of muscle symptoms are also called “skeletal muscular dysfunction.”
The amount of force that a muscle can produce depends on how strong it is. The “endurance” of a muscle is the length of time that it can work before it has to stop because it is tired.
Each muscle in the body is made up of millions of tiny fibers. In people with COPD, these fibers can become smaller, weaker, and might even waste away entirely. This muscle loss affects both strength and endurance.
How does COPD cause lower muscle strength and endurance?
Over time, many people with COPD find that they have a lower amount of muscle strength and endurance than they used to have. This problem is more likely to affect the muscles in their legs than other muscles.1,2,3,4
Patients with COPD often avoid exercise and other physical activities because it makes them feel short of breath. Because they are not using their muscles as often as they should, the muscles start to lose strength and endurance. This can often make patients feel even less motivated to exercise, which causes even more muscle loss. This kind of cycle can be difficult to break.
Poor nutrition and loss of appetite are common problems for COPD patients, and can also have a negative effect on their muscles. Muscles need the right balance of nutrition – especially proteins- to function well. Many COPD patients do not consume enough calories, or enough of the right kinds of nutrients. This can also cause a loss of muscle strength and endurance.
Having COPD can affect the muscles in other ways, too. If patients have low levels of oxygen in their bloodstreams for a long period of time, it can decrease the size of their muscle fibers. For some patients, taking certain kinds of steroids to treat COPD symptoms can have the side effect of making their muscles weaker. Also, some researchers think that COPD can cause a patient’s overall system to become inflamed, gradually weakening the muscles over time.
Are there treatments to improve muscle strength and endurance?
Improving people with COPD's muscle strength and endurance can often improve their overall quality of life. Exercise training is one of the best ways to strengthen muscles and improve endurance. It is very important for people with COPD to exercise and be as active as possible. Regular physical activity can help to improve COPD symptoms and slow down the progress of the disease.2,4Exercise training is an important part of a COPD patient's pulmonary rehabilitation program. There are two types of exercise training – endurance training and strength training. An exercise specialist can design a training program that is just right for each patient’s current strength and how much strength they want to gain.
The pulmonary rehabilitation plan should also include advice from a dietician about how to follow a highly nutritional eating plan. A healthy diet involves:
- Consuming enough calories to power the body’s functions, including the energy needed for regular exercise and physical activity
- Consuming the right balance of nutrients, proteins, carbohydrates, and fats