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Exercise‐Induced Heat Stress Disrupts the Shear‐Dilatory Relationship in the Brachial Artery
Author(s) -
Ives Stephen,
Lefferts Wesley,
Wharton Margret,
Fehling Patricia,
Smith Denise
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.994.8
Subject(s) - medicine , brachial artery , cardiology , crossover study , heat stress , reactive hyperemia , vasodilation , blood pressure , zoology , alternative medicine , pathology , biology , placebo
Heat stress increases cardiovascular strain and is of particular concern in occupations, such as military personnel and firefighters, where individuals are required to perform strenuous work while wearing personal protective equipment (PPE). Sudden cardiac events are the leading cause of duty‐related death among firefighters, accounting for ~50% of fatalities each year. Increased cardiovascular strain may initiate an ischemic condition and heat stress may exacerbate this condition. Understanding the acute effects of exercise‐induced heat stress (EIHS) on vascular reactivity may provide insight into mechanisms precipitating acute coronary events in firefighters. METHODS Using a balanced crossover design, 12 young healthy males performed 100 minutes of moderate‐intensity, intermittent exercise with and without EIHS (PPE or cooling vest, respectively). Measurements of FMD and reactive hyperemia (RH) were performed pre‐ and post‐exercise. RESULTS : During EIHS core temperature was significantly greater (38±0.1 vs. 37±0.1°C). Post‐exercise FMD tended to be suppressed in both conditions, but there were no statistical differences. RH was reduced following control but was increased following EIHS. Thus, normalizing FMD to the shear stimulus (FMD/SS AUC ) revealed a significant reduction in FMD following EIHS only (Pre: 0.22±0.1 and 0.13 ±0.0 vs. post: 0.26±0.1 and 0.05±0.0 %FMD/SS AUC , control vs. EIHS, respectively).CONCLUSION Acute intermittent moderate‐intensity exercise tends to reduce large artery endothelial function, which was aggravated by heat stress, and this may contribute to increased risk of acute coronary events. Support: DHS# EMW‐2010‐FP‐01992.