IMT and Lung Disease

I think the best place to start our journey into Inspiratory Muscle Training (IMT) is by taking a look at perhaps the most obvious place where training your breathing muscles may have a benefit - lung disease.
  People with lung disease like asthma, COPD and fibrosis generally have an increased awareness about their breathing.  The processes affecting their lung function can make breathing harder for any given activity, which means they are exposed to sensations of breathlessness more frequently.  When we perceive (or even anticipate!) the need to breathe harder - like with activity - we may shift breathing patterns to use more secondary muscles (see previous post).  This type of pattern is often inefficient and not sustainable for long periods.  The secondary muscles are quite greedy  - they use lots of energy to work - and can therefore increase the work of breathing (meaning they make breathing feel even harder).
When muscles used for breathing start to fatigue, they will trigger something called the metaboreflex, and blood that would normally flow to your muscles in your arms and legs, is redirected to the muscles used for breathing.  This is because no matter what you are doing - breathing always wins!  
So the situation looks like this:  you start to feel breathless, so you breathe harder.  The harder you breathe, the more energy your breathing muscles need.  The more they need, the less energy flows to your leg muscles.  Now you not only feel breathless, but your legs feel heavy too and you have to stop doing an activity.  
This actually happens to everybody eventually once a certain level of effort is reached- in athletes in happens much, much later into activity.  But for people with severe lung disease, this can happen just from walking up the stairs.  This can then lead to a vicious cycle of inactivity - you fee breathless when you move, so you move less, which makes you more breathless when you do try to move.
In an effort to help people with lung disease move more and reduce sensations of breathlessness, research has focused on the effects of strengthening the breathing muscles, in an effort to delay the metaboreflex.  And the results are promising.  When the respiratory muscles are strengthened, people have reported less breathlessness and improved tolerance to activity (ie they can walk farther).  Although IMT make no changes to lung function, it can improve quality of life.  IMT is easy to use (takes a few minutes a day to perform) and is cost effective and can be a great add-on to managing lung disease!

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