By Nathan Costiuc, MSN, APRN, FNP-BC
Inspiratory muscle training, also known as IMT, is an emerging area of research in the treatment of Obstructive Sleep Apnea (OSA). And although that research is in its early stages, IMT has shown promise as an effective way to improve OSA as an adjuvant to classic treatment models or in patients intolerant of CPAP.
A New Age of Understanding OSA
Modern medicine is turning the corner on understanding the incredible magnitude of sleep apnea. Recent estimates show nearly 45% of adult men and 37% of adult women have OSA – much of this undiagnosed and, thus, undertreated. There are many bottlenecks to proper evaluation and treatment, but one may be patients’ familiarity (and fear) with CPAP devices. The reasoning may sound something like, “I’m not interested in learning if I have sleep apnea because then I’ll have to use that horrible mask!”
What Inspired the Field of IMT Research
It’s possible that IMT may offer a new way to frame early discussions on sleep apnea and its treatment. Educating patients that OSA treatment can include lifestyle modifications like Inspiratory Muscle Training may motivate them to pursue diagnostics. IMT works great as an add-on therapy along with classic CPAP treatment, in a similar way that exercise works in conjunction with anti-hypertensives for HTN treatment.
But it could also be a solution for those not interested in CPAP therapy or those who cannot tolerate its usage or the use of oral appliances. For a group that’s larger than just the patients who are vocal about their distaste for these treatment options, IMT offers a compelling proposition: simple, non-invasive therapy that’s better than no treatment at all.
IMT Mechanism of Action
Unlike CPAP or other sleep therapies, IMT does not directly support your airway—it involves training the surrounding collateral respiratory muscles. While there is still a lack of therapy standardization, the basic idea is to perform inhalational resistance training (also known as inspiratory pressure threshold loading – IPTL) either with specific breathing techniques or by using a variety of available pressure threshold devices.
The goal is to increase the strength of all the muscles involved in breathing, like the diaphragm and intercostals. But where IMT may provide the most benefit for sleep apnea is in the strengthing of those accessory muscles found in the upper airway like the sternocleidomastoid or scalenes group. These are theorized to help prevent or decrease the frequency of relaxative collapse of the upper airway that is common in OSA.
Inspiratory Muscle Training Research to Date
Notably, Inspiratory Muscle Training is an emerging field of study with many unanswered questions about what type of patient it should be used for and how often it should be used, so more research is needed to determine its efficacy as an alternative treatment option for obstructive sleep apnea.
At this point, research is limited and has focused on safety, like one paper published in Sleep. Researchers found that patients undergoing IMT therapy experienced “reductions in systolic/diastolic blood pressures, plasma norepinephrine levels, and nighttime arousals” while reporting enhanced perceived sleep and a lack of negative effect on their AHI scores.1
That said, some efficacy research has arisen since that 2016 study, like a 2020 Randomized Control Trial carried out in Brazil. The study describes an IMT intervention group that showed not only “a reduction in the AHI (31.7 ± 15.9 events/h vs 29.9 ± 15.8 events/h; p < 0.001)” but also improvements in Berlin, PSQI, and Epworth scores.2 These studies had significant limitations due to small sample sizes, but they do offer compelling early findings on the use of IMT in apneic patients.
Where IMT Fits in Modern Apnea Treatment
Due to its nascency in the literature, there is debate around the relevance or clinical applicability of IMT when advanced therapies like PAP are available. However, proponents argue that it is easily accessible and that (with proper education and the selection of low-risk, normotensive, non-arrhythmic patients) it reaches safety thresholds, making IMT reasonable to recommend as part of a larger approach to decreasing apneic episodes and improving AHI scores.
One promising application area is the subset of patients who struggle with compliance. Clinicians treating sleep disturbances are highly familiar with the incredible amount of teaching involved in PAP therapy. But even despite high-quality training, patients still face CPAP intolerance from refractory mask leaks, claustrophobia, latex allergies, etc. Knowing that a therapeutic adjuvant like IMT is available may give them the confidence to be more up-front about their response to treatment, improve patient-provider communication, and help them land on the right sleep therapy.
Is Inspiratory Muscle Training Worth Recommending to Patients?
Inspiratory Muscle Training (IMT) is quickly becoming a viable option for treating OSA. There’s a small but growing body of research to support its use as an alternative or adjunctive to CPAP, yet many patients and physicians have doubts about its efficacy. Whether IMT is worth recommending or not is also going to change based on a provider’s familiarity and expertise with their specific patient population. That said, knowledge is power, so it is ultimately beneficial for patients to be educated on all potential treatment options. This could work to support informed, nuanced discussions on what role IMT could play in their unique medical case.
Nathan Costiuc, MSN, APRN, FNP-BC is a nurse practitioner in West Palm Beach, Florida. He is a frequent contributor to RTSleepWorld.com and Sleep Lab Magazine.
Vranish JR, Bailey EF. Inspiratory Muscle Training Improves Sleep and Mitigates Cardiovascular Dysfunction in Obstructive Sleep Apnea. Sleep. 2016 Jun 1;39(6):1179-85. doi: 10.5665/sleep.5826. PMID: 27091540; PMCID: PMC4863204.
Nóbrega-Júnior JCN, Dornelas de Andrade A, Andrade EAM, Andrade MA, Ribeiro ASV, Pedrosa RP, Ferreira APL, Lima AMJ. Inspiratory Muscle Training in the Severity of Obstructive Sleep Apnea, Sleep Quality and Excessive Daytime Sleepiness: A Placebo-Controlled, Randomized Trial. Nat Sci Sleep. 2020;12:1105-1113 https://doi.org/10.2147/NSS.S269360