Sleep

Steam-assisted respiratory muscle training may improve sleep quality in mild-to-moderate obstructive sleep apnea: a pilot polysomnography study.

TL;DR

Steam-assisted respiratory muscle training did not significantly alter respiratory or sleep continuity indices in mild-to-moderate OSA but was associated with modest changes in REM architecture and limb movements in this non-controlled pilot setting.

Key Findings

Primary outcomes of respiratory indices and sleep continuity metrics remained unchanged after 12 weeks of steam-assisted respiratory muscle training.

  • Primary outcomes included apnea-hypopnea index (AHI), oxygen desaturation index (ODI3), CT90 (percentage of sleep time with oxygen saturation below 90%), sleep efficiency, and wake after sleep onset (WASO).
  • All primary outcome comparisons yielded p > 0.05, indicating no statistically significant changes.
  • The study was a 12-week open-label prospective pilot with 60 enrolled participants, of whom 33 completed the study.
  • Participants underwent individualized inspiratory and expiratory resistance training with adjunctive steam inhalation.
  • The authors concluded the study 'cannot support RMT as an effective primary treatment for OSA at this stage.'

Secondary analyses revealed reduced REM latency and increased REM duration following the intervention.

  • Both REM latency reduction and REM duration increase reached statistical significance (p < 0.05).
  • These findings are described as 'exploratory observations in a non-controlled pilot setting' and should be interpreted cautiously.
  • The changes represent alterations in REM sleep architecture without corresponding improvements in respiratory indices.
  • Larger randomized, sham-controlled trials are recommended to confirm these preliminary results.

Fewer periodic limb movements (PLM) and arousal-related events were observed after the intervention.

  • Reductions in both periodic limb movements and arousal-related events reached statistical significance (p < 0.05).
  • Regression analysis indicated that greater height and BMI were associated with fewer PLM, whereas larger waist circumference predicted more PLM.
  • These findings regarding PLM are described as largely unknown prior to this study in the context of respiratory muscle training.
  • The association between anthropometric variables and PLM was assessed using Mann-Whitney and Fisher tests with significance set at p < 0.05.

Only 33 of 60 enrolled participants completed the 12-week pilot study.

  • The completion rate was 55% (33 out of 60 participants).
  • Participants were described as 'working participants with mild to moderate OSA.'
  • The study authors noted that 'poor adherence limits real-world impact' of standard OSA treatments, and the dropout rate in this pilot highlights similar adherence challenges.
  • The authors called for 'larger randomized, sham-controlled trials with objective adherence monitoring' to address limitations of this design.

The study used a comprehensive polysomnography protocol conducted pre- and post-intervention to assess multiple sleep and respiratory outcomes.

  • PSG was conducted at two time points: before and after the 12-week intervention.
  • Statistical analyses included the Shapiro-Wilk normality test, Paired T-test, Welch test, or Wilcoxon signed-rank test for comparing visits.
  • Wilson confidence intervals were used for reporting responders, and Mann-Whitney and Fisher tests were used for assessing associations.
  • Regression analysis was used to predict change in outcomes.
  • The study design was open-label with no control or sham group, which is acknowledged as a significant limitation.

CPAP adherence limitations motivated the investigation of respiratory muscle training as an alternative approach for OSA management.

  • The authors state that 'sub-optimal adherence to its gold-standard CPAP therapy compels development of alternative approaches.'
  • Respiratory muscle training was hypothesized to 'strengthen airway dilator muscles.'
  • Prior to this study, the effects of respiratory muscle training 'on full polysomnography and periodic limb movements are largely unknown.'
  • The training involved individualized inspiratory and expiratory resistance training combined with adjunctive steam inhalation.

What This Means

This research suggests that a 12-week program combining breathing muscle exercises with steam inhalation did not meaningfully improve the core breathing problems associated with obstructive sleep apnea (OSA), such as the number of breathing pauses during sleep or blood oxygen levels. The study enrolled 60 adults with mild-to-moderate OSA, but only 33 finished the program, and when researchers compared sleep study results before and after the training, the main measures of sleep-disordered breathing and sleep continuity did not change significantly. This means the intervention, as tested here, cannot be recommended as a primary treatment for OSA based on these results. However, some secondary findings were notable. Participants showed changes in REM sleep — the stage of sleep associated with dreaming — including falling into REM sleep faster and spending more time in it. They also experienced fewer involuntary leg movements during sleep and fewer arousals. Body measurements like height, BMI, and waist circumference were associated with how many leg movements participants had, suggesting individual physical characteristics may play a role in this sleep phenomenon. These are considered exploratory findings and should not be interpreted as definitive benefits of the treatment. This research matters because many people with OSA struggle to consistently use CPAP machines, the standard treatment, which drives interest in alternative therapies. However, this pilot study had important limitations — it lacked a control group, had no sham treatment for comparison, and more than a third of participants dropped out. The authors emphasize that larger, well-controlled clinical trials with careful tracking of whether participants actually did the exercises are needed before any firm conclusions can be drawn about whether this type of training offers meaningful benefits for people with OSA.

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Citation

Al-Rammahi U, Soukka T, Rimpil&#xe4; V, Malinen J, Happonen R, Sovij&#xe4;rvi A, et al.. (2026). Steam-assisted respiratory muscle training may improve sleep quality in mild-to-moderate obstructive sleep apnea: a pilot polysomnography study.. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine. https://doi.org/10.1007/s44470-025-00036-w