A. Alfaro-Chaverri, J. Sol, B. Coutinho, B. McGowan, J. Quindry FACSM

University of Montana, Missoula, MT

Woodsmoke (WS) inhalation represents a health problem for firefighters and those who exercise outdoors. Chronic WS inhalation, including airborne particulate ≤2.5 microns in diameter, is associated with reduced life expectancy and increased rates of cardiovascular disease. While the acute responses to WS inhalation are not completely defined, previous studies suggest that oxidative stress accompanies declines in cardiorespiratory function, and some individuals, including those with evening circadian chronotypes and those who are cold pressor test (CPT) sensitive, may be hyperresponsive. PURPOSE: To quantify a series of acute cardiovascular and respiratory responses to WS exposure combined with exercise in evening chronotypes that are also cold pressor test sensitive. METHODS: Twenty active participants (ten males and ten females) were equally selected for the traits of CPT "hyperreactive" + afternoon/evening chronotypes (CPT⁺) and compared with "non-reactive" + morning chronotypes (CPT¯). Participants performed a 120-minutes of exercise at 50% of VO2 max with WS exposure at 250 μg·m¯³. The key dependent variables in this study were heart rate variability (HRV), pulse wave velocity (PWV), pulmonary function testing (PFT). Secondary variables included oxidative stress markers from exhaled breath condensate. The measurements were collected pre-exercise (Pre), immediately post-exercise (Post), and 24 hours post (24 Post). RESULTS: PFT, and oxidative stress markers were not impacted by the exercise exposure challenge. HRV showed significant group difference for InRMSSD and InHF. CPT+ participants exhibited elevated systolic and diastolic blood pressure at Pre, Post and 24 Post time points. CPT⁺ had higher PWV Post metrics (PTT, SBP, DBP, and MAP, Aix) as compared to CPT-. CONCLUSION: Woodsmoke exposure with long duration moderate-intensity aerobic exercise produced exaggerated responses in CPT+ participants for metrics of PVW and BP responses to CPT. While not confirmatory, these findings suggest that some apparently healthy individuals may be at greater risk to WS inhalation, and these responses may be identifiable through simple physiologic testing approaches.

* The funding for the investigation was provided by a USDA Forest Service and the National Institutes of Health.

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