In healthy endurance athletes without asthma, urinary LTE4 decreased after brief maximal exercise in -15 °C with no significant interaction with heat and moisture-exchanging mask (HME) use, and 11β-PGF2α was unaffected by exercise or HME, so the study observed limited evidence of type 2 inflammation with or without an HME.
Key Findings
Results
Urinary LTE4 concentrations decreased 60 minutes after a 4-min maximal running time trial in subzero conditions in healthy athletes.
The decrease was significant: "LTE4 decreased after the 4-min maximal exercise test (p < 0.001)".
23 healthy, recreational-competitive endurance athletes aged 18-53 years without asthma took part.
Urine was sampled pre-exercise and 60 min post-exercise and analysed with repeated-measures ANOVA.
Exercise was a 30-min warm-up followed by a 4-min maximal, self-paced running time trial at -15 °C.
Results
Use of a heat and moisture-exchanging breathing mask (HME) did not significantly alter the LTE4 response to exercise.
The abstract reports no significant interaction between HME use and the LTE4 change.
Participants completed the trial both with and without an HME, in a within-subject design.
The post-exercise decrease in LTE4 occurred regardless of HME condition.
Results
11β-PGF2α responses to exercise were not affected by exercise alone or by HME use.
"There was no effect of exercise alone nor HME on 11β-PGF2α responses to exercise."
11β-PGF2α was measured in urine pre- and 60 min post-exercise.
Analysis used repeated-measures ANOVA.
Conclusions
The study found limited evidence of type 2 inflammation in healthy participants after brief, high-intensity cold-air exercise, with or without an HME.
The mast cell mediators measured were LTE4 and 11β-PGF2α.
LTE4 fell rather than rose after exercise, and 11β-PGF2α did not change.
The cohort was healthy athletes without asthma.
Conclusions
The biomarker outcomes were secondary and not powered in advance, so the findings are exploratory.
The authors state that the biomarker outcomes "were secondary and not powered in advance".
They call for further investigation using more robust airway challenges in athletes.
The trial was registered with ISRCTN on 01 April 2019.
What This Means
This study asked whether a breathing mask that traps heat and moisture (an HME) changes the release of inflammation-related chemicals when people run hard in very cold air. Twenty-three healthy endurance athletes without asthma did a 30-minute warm-up and a 4-minute all-out run at -15 °C, once with the mask and once without. Researchers measured two markers of mast cell activity (LTE4 and 11β-PGF2α) in urine before exercise and 60 minutes afterward.
Urinary LTE4 went down after the hard run, and the mask did not significantly change this pattern. The other marker, 11β-PGF2α, did not change with exercise or with the mask. This research suggests that in healthy athletes, a short, intense run in the cold does not clearly trigger this type of airway inflammation, with or without a mask.
The authors note that these biomarker measures were secondary outcomes and the study was not designed with enough participants to detect small effects. The participants were also healthy, so the results may not apply to people with asthma or exercise-induced airway narrowing. The authors suggest that stronger airway challenges are needed to better understand early airway responses and whether masks could help prevent problems in athletes.
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Hanstock H, Ainegren M, Andersson E, Bäckebjörk E, Stenfors N. (2026). Effect of a breathing mask on type 2 mediator responses to subzero exercise in individuals without asthma.. BMC research notes. https://doi.org/10.1186/s13104-026-08094-w