Pulmonary Function Test: Muscle Strength Test

The Division of Pulmonary Medicine at Cincinnati Children's performs respiratory muscle strength tests.  

Respiratory muscle strength testing is made up of three tests that measure the strength of the muscles you use to breathe. Besides normal breathing, you use your respiratory muscles for deep breathing during exercise and when coughing to clear the lungs.

Respiratory muscle strength testing is particularly important for patients with generalized muscle weakness such as muscular dystrophy.

Respiratory muscle strength is measured by having your child place padded nose clips on his or her nose and place their mouth around a clean filtered mouthpiece. Respiratory muscle strength testing is comprised of three separate tests:

Maximal Inspiratory Pressure (MIP)

This test measures the strength of the muscles used to take in deep breaths.  Starts with normal resting breathing. This is followed by blowing out all of the air until almost completely empty. Then, when the mouthpiece closes, your child sucks in as hard as he or she can. The mouthpiece closes for only a few seconds. The harder your child can suck in, the stronger the inspiratory muscles.

Maximal Expiratory Pressure (MEP)

This test measures the strength of the muscles used to cough. Starts with normal resting breathing. This is followed by taking in very deep breaths. Then, when the mouthpiece closes, your child will blow out as hard as he or she can. The mouthpiece closes for only a few seconds. The harder your child blows out, the stronger the expiratory muscles.

Maximum Voluntary Ventilation (MVV)

This test measures the strength of both the inspiratory and expiratory muscles. It also indirectly measures how well your child can move air into and out of the lungs. Starts with normal resting breathing. Then, when prompted, your child will start breathing in and out deeply and quickly, moving as much air as he or she can. The test ends automatically after 12 seconds of rapid breathing.

How Long Does It Take?

This test usually takes less than 20 minutes to complete.

Do I Need to Prepare My Child for This Test?

There is no special preparation for this test.

Your child may get a little lightheaded for a few seconds after performing the maximum voluntary ventilation (MVV) test.

Otherwise, there are no side effects for respiratory muscle strength testing. Your child may resume normal activity after testing.


Last Updated 08/2013