Underground climate therapy may be beneficial for individuals with chronic respiratory diseases.Speleotherapy, or underground climate therapy, may benefit individuals with chronic respiratory diseases, such as asthma, chronic obstructive pulmonary disease (COPD), or long COVID, a study suggests.
The study included 208 individuals diagnosed with bronchial asthma, COPD, or long COVID. Of these, 42 had long COVID. The participants were randomized 1:1 to either a 3-week course of speleotherapy (six sessions, 2 hrs/week) or standard background therapy.
Wrapped in sleeping bags, the participants lay on reclining chairs for 1.5–2 hrs. At the beginning of each session, general physical and breathing exercises were done for 5–10 min. Assessments were conducted before treatment (T1), immediately after treatment (T2), and 3 months after completing treatment (T3). [Sci Rep 2026;16:15986]
In the overall cohort, the intervention group had improved respiratory muscle strength (Maximal Inspiratory Pressure: p=0.002; Maximal Expiratory Pressure: p=0.018) and dysfunctional breathing as reflected by their Nijmegen Questionnaire (NQ) scores (T2: p=0.007; T3: p=0.017) compared with the control group. Despite the statistically significant improvements, the researchers noted that these were modest and should thus be interpreted with caution.
Long COVID
Compared with the control group, the intervention group had significant improvements in NQ (T2: p=0.014) and Fatigue Assessment Scale (FAS; T3: p<0.05) scores, as well as in the dyspnoea (T2: p=0.026; T3: p=0.001), problems with stair climbing/muscle exertion (T2: p=0.042), and anxiety/sleep disturbance (T2: p=0.021) domains in the long COVID questionnaire.
“The reduction in NQ score supports the hypothesis of improved dysfunctional breathing patterns, although these findings should be interpreted with caution given the small sample size of [this] subgroup,” the researchers said.
They added that the improvement in NQ score may also be associated with reduced fatigue severity, as reflected by the lower FAS score. “The median change of −3 points [is] slightly below the proposed minimal clinically important difference of approximately 4 points for the FAS, indicating a trend toward clinically meaningful improvement but warranting cautious interpretation.”
Low-risk complementary Tx
Speleotherapy, usually done in natural caves or decommissioned mines, is rooted deeply in Central and Eastern Europe health traditions, as well as in Western Asia, as a complementary treatment for allergic respiratory diseases. [Asthma and Allergy 2017;2:2307-3373; Allergol Immunopathol (Madr) 2004;32:289-294]
Evidence suggests that the benefits of speleotherapy may be attributed to reduced inhaled irritants from extremely pure air that is free from pollen, dust, and spores, as well as its thermophysical effect. [https://freidok.uni-freiburg.de/data/1583, accessed 24 July 2026]
“As the air is warmed to 37°C within the airways, the relative humidity drops to <30 percent, facilitating fluid absorption from the bronchial mucosa and promoting airway clearance … [Moreover,] the increased CO2 concentration in the air (0.08–0.4 percent, compared with 0.04 percent in ambient air) may promote relaxation of the respiratory muscles,” the researchers noted.
Another potential mechanism is vagal nerve stimulation. [Osteopathische Medizin 2021;22:10-15] “The cool environment, exceptional stillness, and unique underground setting probably have vagotonic effects, contributing to reduced respiratory rates and dysfunctional breathing,” they said.
The researchers called for more studies to further evaluate the underlying pathophysiological mechanisms of the observed effects, such as the vagus nerve-stimulating influence of speleotherapy on respiratory diseases and stress-related health disorders. “[Speleotherapy] represents a cost-effective, low-risk, and long-lasting treatment option [for chronic respiratory diseases].”