Here you can find completed and ongoing studies conducted with the WellO2 Steam Breathing Trainer.

Peer-reviewed scientific publications

Clinical study in individuals with obstructive sleep apnea

Al-Rammahi U, Soukka T, Malinen J, Happonen RP, Sovijärvi A, Anttalainen U. Effects of steam-assisted respiratory muscle training on sleep apnoea symptoms and pulmonary function in men and women: a pilot study. Sleep Breath. 2025;29(5):286. doi:10.1007/s11325-025-03449-2

Available at: DOI link

Clinical study in individuals with obstructive sleep apnea - polysomnography analysis

Al-Rammahi U, Soukka T, Rimpilä V, Malinen J, Happonen RP, Sovijärvi A, Anttalainen U. Steam-assisted respiratory muscle training may improve sleep quality in mild-to-moderate obstructive sleep apnea: a pilot polysomnography study. J Clin Sleep Med. 2026;22(1):32. doi:10.1007/s44470-025-00036-w

Available at: DOI link

(This publication is based on the same clinical study as the 2025 Sleep and Breathing paper, but includes detailed polysomnography (PSG) analysis.)

Clinical study in individuals with asthma

Kuronen I, Heinijoki J, Sovijärvi A. Effects of low workload respiratory training with steam inhalation on lung function in stable asthma: a controlled clinical study. Clin Physiol Funct Imaging. 2024;44(1):100-111. doi:10.1111/cpf.12856

Available at: DOI link

Clinical study in individuals with voice symptoms

Huttunen K, Rantala L. Effects of humidification of the vocal tract and respiratory muscle training in women with voice symptoms: a pilot study. J Voice. 2021;35(1):158.e21-158.e33. doi:10.1016/j.jvoice.2019.07.019

Available at: DOI link

Respiratory measurement validation study

Ryynänen H, Sovijärvi A, Kuronen I, Ahokas EK, Valtonen M, Ihalainen JK, Multanen J. Validity and short-term repeatability of a novel hand-held respiratory health meter for the assessment of dynamic maximal respiratory pressures in healthy young adults. Med Devices (Auckl). 2025;18:297-308. doi:10.2147/MDER.S515777

Available at: DOI link

Master's thesis works

·        Wenning J. (2021), University of Jyväskylä. Respiratory muscle power, endurance performance, and perceived strain.

·        Mäkelä T. (2022), University of Jyväskylä. Respiratory muscle power production and aerobic performance (randomized controlled trial).

·        Ihalainen J. and Valtonen M. (2021), University of Jyväskylä. Respiratory parameters and endurance performance.

·        Ryynänen H. (2022), University of Jyväskylä. Measurement of inspiratory and expiratory pressures (MIP/MEP).