Muscle wasting in COPD - update
People with COPD also experience changes in the muscles that control strength and movement, as well as support the body. My research will look into these changes and why they happen.
Overview:
People with COPD also experience changes in the muscles that control strength and movement, as well as support the body. My research will look into these changes and why they happen.
People with COPD experience a reduction in blood flow, and alterations in? the size and thickness of their muscles. This is due to changes in the muscle fibres present in the large thigh muscle, called vastus lateralis. Muscles are made up of different fibre types that make energy in different ways:
- Type I, or ‘slow twitch’ fibres, contain lots of tiny blood vessels called capillaries. They contract slowly, releasing energy at a slower rate, but can keep going for a long time.
- Type II, or ‘fast twitch’ muscle fibres contain lots of stored energy that is easy to access for short bursts of energy. They contract quickly, but rapidly tire.
As part of my study, I’ve analysed results from previous research that has been carried out on tissue samples from the muscles of people with COPD. These studies confirm that the number and distribution of the muscle fibre types I and II change in people with COPD.
Methods
In our study, we worked with30 participants: 10 patients with COPD and muscle wasting; 10 patients with COPD and normal muscles; and 10 people without COPD of the same age and gender as those with COPD. Participants were asked if they were current or ex-smokers, about their smoking history, how many exacerbations they had experienced within the last year, and to complete both a health-related quality of life questionnaire, and a physical activity level questionnaire.
Spirometry tests were performed to measure lung function, as well as measuring the amount of body fat and muscle, thigh muscle strength and the ability to walk for 6 minutes.
Results:
When we compared the results for all these tests, we found that there were more slow-twitch muscle fibres in people with low breath test results, who had smoked more cigarettes each day over a longer time period, and who had experienced more exacerbations within the last year.
These results support previous studies that show that the ability of the muscles to use and transport oxygen in patients with COPD is changed and reduced due to changes in the types of muscle fibres present; and that this continues as the COPD progresses.
Next steps:
The next stage of my research will concentrate on looking at inflammation and oxygen transportation in people with COPD. We know that reduced oxygen and swelling are common, especially during exacerbations, and I will be trying to learn more about how this affects skeletal muscle.
Posted by Ramzi Lakhdar