What is Inspiratory Muscle Strength Training (IMST)?
Targeting the Muscles We Use to Inhale
Breathing air into our lungs requires a muscular effort. Specifically, the diaphragm is the prime muscle that allows us to inspire. The diaphragm is a flat muscle that, when it contracts, raises the rib cage, expanding the lungs and allowing air to rush in to balance the pressure. The diaphragm is a hard-working muscle, as we are always breathing. Fortunately, it is well-suited to its task as the diaphragm is very resistant to fatigue, much more so than any of our skeletal muscles.
The diaphragm is assisted by the external intercostals, which also work to expand the ribs. Both of these muscles go to work every time we inhale.
If you are wondering, exhalation is usually a passive process that requires no muscular action. When we need to exhale forcefully (such as during exercise or when blowing up a balloon), we use our abdominal muscles and the internal intercostals to draw the rib cage down more quickly.
How IMST Works: Resistance for Respiratory Muscles
Inspiratory muscle strength training (IMST) uses resistive devices to increase the pressure required to inhale. This makes the diaphragm work harder than usual to inflate the lungs. As with any muscle, applying transient stress will make it adapt and become stronger. In theory, IMST can strengthen the inspiratory muscles and, consequently, make breathing feel easier.
Key Benefits of IMST for Health and Performance
Enhancing Respiratory Function and Lung Capacity
IMST works! Meaning it consistently increases maximum pulmonary inspiratory strength (PImax) when performed on most days of the week. Interventions over 6 weeks using resistance of 50%+ PImax have also improved exercise capacity.
Improving Exercise Tolerance and Athletic Performance
Fatigue of the respiratory muscles can impair exercise performance. So by strengthening the respiratory muscles, IMT can make them more resistant to fatigue and improve exercise performance in the general population. Improvements in exercise capacity from IMST appear more likely in subjects who are less fit and in those with longer exercise performance.
Potential Benefits for Blood Pressure, Sleep Apnea, and patients with cardiorespiratory disorders
Hypertension, or chronically elevated resting blood pressure, impacts almost half of US adults. IMST has been found to reduce systolic and diastolic blood pressure and lower resting heart rate.
Sleep apnea, a condition characterized by repeated interruptions in breathing during the night, is a common complaint. A recent meta-analysis of clinical trials examining the impact of IMST on patients with sleep apnea concluded that IMST improved sleep quality and reduced daytime sleepiness.
Patients with respiratory disorders, such as COPD, are often referred to supervised exercise in a pulmonary rehabilitation program. In a comparison study, IMST was found to improve quality of life and exercise capacity in populations with lung disease, though to a lesser extent than pulmonary rehabilitation, so IMST may best be used as an adjunct therapy in that population.
A meta-analysis of clinical trials evaluating IMST in asthma patients found consistent improvements in PImax, but only mild evidence of improvements in exercise capacity or quality of life. Likewise, heart disease patients who trained with IMST showed significant improvement in PImax but no effect on 6 min walk performance.
Implementing IMST
All told, IMST has shown potential to improve health in a variety of ways. In general, these improvements are most noticeable in people who are less fit or have some health issues (hypertension, sleep apnea) at the onset of training.
The time burden of IMST is quite low, with 5-10-minute daily training sessions shown to increase PImax. The financial cost of IMST equipment is not prohibitive either, as popular IMST devices retail for $50-100. It may be worth your while to explore training your inspiratory muscles. You should expect to notice benefits within 4-8 weeks of starting.
FAQs
What is inspiratory muscle strength training (IMST)?
Inspiratory muscle strength training (IMST) is a breathing exercise that uses a handheld resistance device to make inhalation more challenging. By increasing the effort required to breathe in, IMST strengthens the diaphragm and other muscles involved in breathing, much like lifting weights strengthens skeletal muscles.
Who can benefit from IMST?
IMST may benefit a variety of people, including individuals with high blood pressure, sleep apnea, chronic lung conditions, and those looking to improve exercise tolerance. Research suggests the greatest benefits are often seen in people who are less physically fit or have underlying health conditions, though healthy individuals may also experience improvements in respiratory muscle strength.
How long does it take to see results from IMST?
Many studies have found improvements in inspiratory muscle strength within 4–8 weeks of consistent training. Most protocols involve short daily sessions lasting only 5–10 minutes, making IMST a relatively time-efficient intervention compared to many other exercise programs.
Can IMST improve athletic performance?
Possibly. Strengthening the muscles used for breathing may help reduce respiratory muscle fatigue during exercise, which could improve endurance and exercise capacity. However, the benefits appear to be more noticeable during longer-duration activities and among individuals who are not already highly trained athletes.
Is IMST a replacement for regular exercise?
No. While IMST can strengthen breathing muscles and may provide benefits for blood pressure, sleep quality, and exercise tolerance, it does not replace the wide-ranging cardiovascular, metabolic, musculoskeletal, and mental health benefits of regular physical activity. For most people, IMST is best viewed as a complement to an active lifestyle rather than a substitute for exercise.
References
1Seixas, M. B., Almeida, L. B., Trevizan, P. F., Martinez, D. G., Laterza, M. C., Vanderlei, L. C. M., & Silva, L. P. (2020). Effects of Inspiratory Muscle Training in Older Adults. Respiratory care, 65(4), 535–544. https://doi.org/10.4187/respcare.06945
2Lista-Paz, A., Bouza Cousillas, L., Jácome, C., Fregonezi, G., Labata-Lezaun, N., Llurda-Almuzara, L., & Pérez-Bellmunt, A. (2023). Effect of respiratory muscle training in asthma: A systematic review and meta-analysis. Annals of physical and rehabilitation medicine, 66(3), 101691. https://doi.org/10.1016/j.rehab.2022.101691
3Mador, M. J., & Acevedo, F. A. (1991). Effect of respiratory muscle fatigue on subsequent exercise performance. Journal of applied physiology (Bethesda, Md. : 1985), 70(5), 2059–2065. https://doi.org/10.1152/jappl.1991.70.5.2059
4Illi, S. K., Held, U., Frank, I., & Spengler, C. M. (2012). Effect of respiratory muscle training on exercise performance in healthy individuals: a systematic review and meta-analysis. Sports medicine (Auckland, N.Z.), 42(8), 707–724. https://doi.org/10.1007/BF03262290
5Zheng, S., Zhang, Q., Li, S., Li, S., Yao, Q., Zheng, X., Li, G., Zeng, Y., Chen, L., Chen, S., He, L., Zou, J., & Zeng, Q. (2023). Effects of inspiratory muscle training in patients with hypertension: a meta-analysis. Frontiers in cardiovascular medicine, 10, 1113509. https://doi.org/10.3389/fcvm.2023.1113509
6Dar, J. A., Mujaddadi, A., & Moiz, J. A. (2022). Effects of inspiratory muscle training in patients with obstructive sleep apnoea syndrome: a systematic review and meta-analysis. Sleep science (Sao Paulo, Brazil), 15(4), 480–489. https://doi.org/10.5935/1984-0063.20220081
7Ammous, O., Feki, W., Lotfi, T., Khamis, A. M., Gosselink, R., Rebai, A., & Kammoun, S. (2023). Inspiratory muscle training, with or without concomitant pulmonary rehabilitation, for chronic obstructive pulmonary disease (COPD). The Cochrane database of systematic reviews, 1(1), CD013778. https://doi.org/10.1002/14651858.CD013778.pub2
8Fabero-Garrido, R., Del Corral, T., Plaza-Manzano, G., Sanz-Ayan, P., Izquierdo-García, J., & López-de-Uralde-Villanueva, I. (2024). Effects of Respiratory Muscle Training on Exercise Capacity, Quality of Life, and Respiratory and Pulmonary Function in People With Ischemic Heart Disease: Systematic Review and Meta-Analysis. Physical therapy, 104(3), pzad164. https://doi.org/10.1093/ptj/pzad164
9Kendall, F., Oliveira, J., Peleteiro, B., Pinho, P., & Bastos, P. T. (2018). Inspiratory muscle training is effective to reduce postoperative pulmonary complications and length of hospital stay: a systematic review and meta-analysis. Disability and rehabilitation, 40(8), 864–882. https://doi.org/10.1080/09638288.2016.1277396
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