Expiratory Muscle Strength Training (EMST), along with Inspiratory Muscle Training (IMT), is an element of Respiratory Muscle Training (RMT). Respiratory Muscle Training is a treatment that uses both these therapies to help you enhance your breathing muscle function. This may be to improve your health, relieve symptoms of a medical condition, improve general physical and breathing fitness and increase sports performance.

During normal expiration, your lungs will start to deflate as your inspiratory muscles relax. However, during periods of active breathing, such as extreme exercise or coughing, your expiratory muscles may contract to force air out of your lungs.

Expiratory Muscle Strength Training

EMST, or EMT (expiratory muscle training), will improve the breathing muscle strength and function of your expiratory muscles. These are your internal intercostals, rectus abdominis, external and internal obliques and transversus abdominis.

Who Is EMST For?

Anyone who uses forced expiratory breathing or who experiences the need to empty air from their lungs more than normal will benefit from this type of breathing training.

lady sitting on sofa coughing
(Photo by Annie Spratt on Unsplash)

For instance, research shows there to be a beneficial use of:

Expiratory Muscle Strength Training – Why Do It?

During inspiration, you actively use your inspiratory muscles to breathe in, primarily your diaphragm and external intercostals. Expiration however is generally passive. This is because you naturally exhale as your inspiratory muscles relax. As a result, air passively leaves your lungs.

Normally, during breathing at rest, you will not be using any expiratory muscles. However, during heavy ‘exercise’ your expiratory muscles will play an active role in breathing. During forced expiration, when there’s a need to empty more air from your lungs than normal, the accessory muscles of your abdomen (rectus abdominis, transverse abdominis, obliques) and the internal intercostals, contract, forcing the diaphragm upwards and pushing more air out.

Furthermore, if your respiratory passageways are narrowed or blocked with mucus, such as in chronic bronchitis, expiration becomes an active process.

Expiratory muscle training is not as widely studied as inspiratory muscle training. However, the expiratory breathing muscles are likely to respond to the overload principle of resistance training, in the same way as inspiratory muscles and skeletal muscles.

Effects of Expiratory Muscle Strength Training

There is evidence that EMST improves maximal expiratory pressure (MEP) in certain medical conditions. Maximal expiratory pressure is a measurement that reflects the strength of your abdominal muscles and other expiratory muscles. It is an indicator of respiratory weakness. Therefore, strengthening your expiratory muscles with EMT is beneficial as it will improve your maximal expiratory pressure.

Concurrent Inspiratory And Expiratory Muscle Training

Two studies in healthy people implementing simultaneous Inspiratory Muscle Training (IMT) and Expiratory Muscle Training (EMT) within the same breath cycle, found that this concurrent training actually reduces training responses.

One study finds that there is no significant change in Maximum Inspiratory Pressure (MIP) or Maximum Expiratory Pressure (MEP).

The second study reports only modest changes in MIP and MEP. Furthermore, participants describe the concurrent loading of IMT and EMT cycles to be uncomfortable. They also report it to be extremely difficult to train with maximal effort when loading both breathing phases.

Generally, studies suggest that care should be taken when using concurrent IMT and EMT. This is because loading both phases of the breathing cycle simultaneously (training inspiratory and expiratory muscles at the same time) generates suboptimal improvements in respiratory muscle strength.

There is, therefore, a strong argument to perform expiratory and inspiratory muscle training independently of each other.

What is Inspiratory Muscle Training?

Where EMST exercises your expiratory muscles, IMT exercises your inspiratory muscles. Inspiratory muscle training (IMT) has proven benefits for respiratory fitness in health, fitness and sports training, including improving sports performance. You can find out how to train your inspiratory muscles, in What is Inspiratory Muscle Training?