Expiratory muscle strength training versus Incentive Spirometry: what’s the difference?

Published: February 23rd, 2015

Category: UAD Student Blog

A common question received by the speech-language clinicians at the Center for Movement Disorders and Neurorestoration is, “What is the difference between expiratory muscle strength training (EMST) and incentive spirometry (IS)?” Because both devices focus on improving the respiratory system, it is not surprising that their uses are often confused. However, there are many significant differences; the primary difference being that EMST target muscle strength while IS targets airflow and muscle endurance. Additionally, expiratory muscle strength trainers and incentive spirometers are used by different populations and are aimed at producing different results (i.e., tracheal and upper airway pressure for EMST, and lung ventilation with IS). However, they do have one thing in common; both devices will make you ask, “When did breathing become so hard?!”


EMST has been studied by scientists at the University of Florida as a method of strengthening the expiratory muscles in people with stroke, Parkinson’s disease and other neurodegenerative disorders. It has been found that strengthening these muscle groups can improve cough and swallow function, thereby reducing the risk of uncompensated penetration and aspiration of foods and liquids.

An expiratory muscle strength trainer is a small, hand-held device that houses a calibrated, spring-operated valve. When the user blows into the device, he or she must create enough pressure to open the valve and let the air through. The pressure level required to open the valve is set by the clinician and varies from person to person. A typical treatment lasts four to five weeks, and requires participants to complete 25 breaths per day (5 sets of 5 breaths) five days per week. Clinicians refer to this as the “power of five.” Throughout the treatment period, the EMST device will be recalibrated to account for the user’s increasing strength. Although this device is commonly used by patients with Parkinson’s disease and other disorders, it can also be used by healthy individuals to increase vocal intensity in singers and exhaled air pressure in musicians, and decrease the perception of breathlessness in athletes.

 Various EMST devicesFigure 1. Various EMST devices. Nose clips are worn and the cheeks are secured around the mouthpiece to ensure that no air escapes.

Incentive Spirometry

Although incentive spirometry is also used for respiratory purposes, it has a completely different purpose than EMST. While EMST focuses on increasing expiratory pressure and muscle strength, incentive spirometry focuses on inhaled and exhaled air flow and lung volume. Incentive spirometers are generally used by individuals who are recovering from surgery, often pulmonary or cardiac surgery, and are experiencing painful respiration during recovery. Because inhaling deeply causes pain, patients tend to keep their breaths very shallow, never fully filling their lungs. This can cause the alveoli (tiny air sacs where gas exchange occurs) to become stagnant and potentially harbor infection. For this reason, incentive spirometry aims to reopen up those alveoli and get air flowing in the smallest diameter airways within the lungs. When using an incentive spirometer, the patient breathes in and out through the mouthpiece, and is able to visualize the rate of airflow.  The patient inhales as deeply as possible and then exhales maintaining a consistent rate of airflow. The patient should repeat these long deep breaths at least 10 times every hour.

Incentive spriometry

Figure 2. Incentive spirometer with airflow values labeled on the column, and a flexible mouthpiece.

Hopefully you can “breathe easy” now that the many differences between these two devices have been made clear.


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