The respiratory system has long been a target of the commercial health and fitness industry. This is due to several reasons, the most recent being the ongoing COVID-19 pandemic that has focussed attention on respiratory health and the means (proven or otherwise) to enhance it. We’ll get to that shortly.

Even before COVID-19, chronic respiratory disease (like chronic obstructive pulmonary disease) was the third leading cause of death worldwide (World Health Organization 2021). Respiratory health has also become an important public health issue due to climate change and worsening air quality (Barnes et al. 2013). Another, more cynical, explanation for the commercial interest in respiratory health is that respiratory physiology is a relatively complex area that’s less well understood by the public; as such, its basic mechanisms are more easily misappropriated for monetary gain.

The respiratory system comprises the upper and lower airways, the lungs, and the respiratory muscles that mostly attach to the ribs. This coordinated arrangement moves air from the atmosphere into the lungs, where oxygen can diffuse into the blood and be delivered to tissues of the body. Because of its multiple components, the respiratory system presents a range of potential therapeutic targets for marketing claims. With most interventions, those claims are a mix of the plausible and the absurd.

Let’s sort the science from the pseudoscience.

The Good

The good news is that there are several proven ways to improve respiratory function. Breathing interventions—which include deep breathing, pursed-lip breathing, and diaphragmatic breathing—are considered broadly effective in the field of pulmonary rehabilitation for patients. For instance, pursed-lip breathing (PLB) is a technique involving deep inhalations, typically through the nose, and long, slow exhalations through “pursed” or “puckered” lips. Using PLB at rest has been shown to improve breathing “efficiency” in patients with obstructive lung disease, thereby relieving breathlessness and increasing oxygenation of the blood (Thoman et al. 1966; Breslin 1992; Marciniuk et al. 2011). In the same patients, PLB might also increase exercise tolerance (Ubolnuar et al. 2019). One study even found that deep, slow breathing resulted in changes to brain activity (Critchley et al. 2015), which might explain purported decreases in arousal, anxiety, and depression with this type of breath control (Zaccaro et al. 2018).

Inspiratory muscle training (IMT) is another potential therapeutic intervention. As with every muscle in the body, the respiratory muscles (including the diaphragm and intercostals) can be strengthened through regular training. Respiratory training devices provide a resistance against which the inspiratory muscles must work to generate airflow. Over time, the resistance can be increased to evoke progressive adaptation. Respiratory muscle training is analogous to weight training for the limb muscles and will typically improve the scores obtained in a clinical lung function test (Bostanci et al. 2019). Respiratory muscle training was also shown to improve maximal fitness in healthy people by delaying fatigue of the respiratory muscles (Sheel 2002) and reduce sensations of breathlessness in respiratory patients (Beaumont et al. 2018).

 

 

The Bad

There are important caveats to these data that are often lost in the noise of marketing rhetoric. Breathing training, such as that described above, might improve exercise capacity in respiratory patients not by improving their fitness, per se, but by addressing their dysfunctional breathing and reducing breathlessness. This means that, in healthy people with normal lung function, the potential benefits will be muted.

The same can be said for respiratory muscle training devices: In someone with healthy baseline function, the benefits may be limited. This is because, in most cases, the healthy respiratory system is overbuilt for its demands (Dempsey et al. 2020). What’s more, respiratory muscle training devices don’t influence the airways or the lungs but rather the respiratory muscles. This is an important distinction. There are no commercial interventions (exercises, devices, or supplements) that can increase your lung size. Lung size is determined by genetics, just like height, eye color, and shoe size. Accordingly, once you’ve physically matured (usually by your early twenties) your stature and lung size are set. Be wary of any product claiming the contrary.

 

 

The Ugly

Throughout the commercial world, a void created by scientific naiveté will be quickly filled by a “health guru” touting unproven remedies. Respiratory physiology is no different. The COVID-19 pandemic provided the perfect opportunity for snake oil salesmen to capitalize on widespread fear and confusion to sell breathing techniques, lung cleansing supplements, immune-boosting vaping devices, and respiratory muscle trainers on the premise they’ll protect you from the SARS-CoV-2 virus. They won’t. Nor will respiratory training help to boost immunity, promote healing, detox the lungs, or cure disease.

Even popular breathing techniques such as Buteyko conflate plausible and implausible claims. On the one hand, the conventional aspects of Buteyko (deep breathing and breath hold) appear to improve quality of life and reduce the need for medication in people with asthma (Burgess et al. 2011; Santino et al. 2020). On the other hand, Buteyko’s promotion of mouth taping to force nasal breathing during sleep was shown to have no effect on asthma control (Cooper et al. 2009), and the emphasis on Buteyko’s long breath holds (more than twenty-five seconds) could be dangerous for people with respiratory disease. Even some of the founding principles of Buteyko have been disproven in empirical research (Courtney and Cohen 2008). It’s a wonderful example of how genuine benefits of a product or practice can be undermined by a dogmatic obsession with quack medicine and pseudoscience.

Other commercial products, such as nasal strips and oxygenated beverages, claim to improve exercise outcomes but are either unproven or disproven (Dinardi et al. 2021; Piantadosi 2006). A review in the British Journal of Sports Medicine stated concisely that performance enhancing claims for oxygenated water “cannot be taken seriously” (Piantadosi 2006). Canned oxygen—oxygen canisters designed to be inhaled before exercise—has no obvious or lasting effect on exercise capacity. One manufacturer of a concentrated oxygen product even went so far as to publish an online press release that mimicked the appearance of a peer-reviewed scientific journal article, presumably in an effort feign scientific legitimacy. The industry is unscrupulous.

 

Take Home Messages

Respiratory training can be hugely beneficial for certain groups, but it’s a poorly understood area that’s open to exploitation. Commercial respiratory products often claim “immune boosting” or “healing” properties that aren’t supported by the evidence. This can have profound repercussions on population health. In fact, real harm occurs whenever people falsely believe a product or practice will protect them from harm. That’s why in our modern society, characterized by commercialism, fake news, and social media, it’s never been more important to draw a clear distinction between science and pseudoscience. As we forge into 2022, “The Skeptic’s Guide to Sports Science” column will continue to frame health and fitness through the critical lens of scientific skepticism, holding the industry to account for its unproven claims.

Happy holidays, everyone!

References

Barnes, C.S., N.E. Alexis, J.A. Bernstein, et al. 2013. The Journal of Allergy and Clinical Immunology 1(2): 137–141. Available online at https://www.jaci-inpractice.org/article/S2213-2198(12)00005-0/fulltext.

Beaumont, M., P. Forget, F. Couturaud, et al. 2018. Effects of inspiratory muscle training in COPD patients: A systematic review and meta-analysis. Clinical Respiratory Journal 12(7): 2178–2188. doi:10.1111/crj.12905.

Bostanci, Ö., H. Mayda, C. Yılmaz, et al. 2019. Inspiratory muscle training improves pulmonary functions and respiratory muscle strength in healthy male smokers. Respiratory Physiology & Neurobiology 264: 28–32. doi:10.1016/j.resp.2019.04.001.

Breslin, E.H. 1992. The pattern of respiratory muscle recruitment during pursed-lip breathing. Chest 101(1): 75–78. Available online at https://journal.chestnet.org/article/S0012-3692(16)33124-5/fulltext.

Burgess, J., B. Ekanayake, A. Lowe, et al. 2011. Systematic review of the effectiveness of breathing retraining in asthma management. Expert Review of Respiratory Medicine 5(6):789–807. doi:10.1586/ERS.11.69.

Cooper, S., J. Oborne, T. Harrison, et al. 2009. Effect of mouth taping at night on asthma control—a randomised single-blind crossover study. Respiratory Medicine 103(6): 813–819. doi:10.1016/j.rmed.2009.02.003.

Courtney, R., and M. Cohen. 2008. Investigating the claims of Konstantin Buteyko, M.D., Ph.D.: The relationship of breath holding time to end tidal CO2 and other proposed measures of dysfunctional breathing. Journal of Alternative and Complementary Medicine 14(2): 115–123. doi:10.1089/acm.2007.7204.

Critchley, H.D., A. Nicotra, P.A. Chiesa, et al. 2015. Slow breathing and hypoxic challenge: Cardiorespiratory consequences and their central neural substrates. PloS One 10(5): e0127082. doi:10.1371/journal.pone.0127082.

Dempsey, J.A., A. La Gerche, J.H. Hull. 2020. Is the healthy respiratory system built just right, overbuilt, or underbuilt to meet the demands imposed by exercise? Journal of Applied Physiology (1985) 129(6): 1235–1256. doi:10.1152/japplphysiol.00444.2020.

Dinardi, R.R., C.H.S. Ferreira, G.S. Silveira, et al. 2021. Does the external nasal dilator strip help in sports activity? A systematic review and meta-analysis. European Archives of Oto-Rhino-Laryngology and Head & Neck 278(5): 1307–1320. doi:10.1007/s00405-020-06202-5.

Marciniuk, D.D., D. Goodridge, P. Hernandez, et al. 2011. Managing dyspnea in patients with advanced chronic obstructive pulmonary disease: A Canadian Thoracic Society clinical practice guideline. Canadian Respiratory Journal 18(2): 69–78. Available online at https://www.hindawi.com/journals/crj/2011/745047/.

Piantadosi, C.A. 2006. “Oxygenated” water and athletic performance. British Journal of Sports Medicine 40(9): 740. doi:10.1136/BJSM.2006.028936.

Santino, T.A., G.S.S. Chaves, D.A. Freitas, et al. 2020. Breathing exercises for adults with asthma. Cochrane Database of Systematic Reviews 2020(3). doi:10.1002/14651858.CD001277.pub4.

Sheel, A.W. 2002. Respiratory muscle training in healthy individuals: Physiological rationale and implications for exercise performance. Sports Medicine (Auckland, NZ) 32(9): 567–581. doi:10.2165/00007256-200232090-00003.

Thoman, R.L., G.L. Stoker, J.C. Ross. 1966. The efficacy of pursed-lips breathing in patients with chronic obstructive pulmonary disease. The American Review of Respiratory Disease 93(1):100–106. Available online at https://pubmed.ncbi.nlm.nih.gov/5901381/.

Ubolnuar, N., A. Tantisuwat, P. Thaveeratitham, et al. 2019. Effects of breathing exercises in patients with chronic obstructive pulmonary disease: Systematic review and meta-analysis. Annals of Rehabilitation Medicine 43(4): 509–523. doi:10.5535/arm.2019.43.4.509.

World Health Organization. 2021. Chronic obstructive pulmonary disease (COPD). Available online at https://www.who.int/news-room/fact-sheets/detail/chronic-obstructive-pulmonary-disease-(copd).

Zaccaro, A., A. Piarulli, M. Laurino, et al. 2018. How breath-control can change your life: A systematic review on psycho-physiological correlates of slow breathing. Frontiers in Human Neuroscience 12: 353. doi:10.3389/fnhum.2018.00353.