title: Effects of Low-Dose Aspirin Therapy on Thermoregulation in Firefighters.
abstract: BACKGROUND
  Heart attack is the most common cause of line-of-duty death in the fire service. Daily aspirin therapy is a preventative measure used to reduce the morbidity of heart attacks but may decrease the ability to dissipate heat by reducing skin blood flow.
  
  
  METHODS
  In this double-blind, placebo-controlled, crossover study, firefighters were randomized to receive 14 days of therapy (81-mg aspirin or placebo) before performing treadmill exercise in thermal-protective clothing in a hot room [38.8 ± 2.1°C, 24.9 ± 9.1% relative humidity (RH)]. Three weeks without therapy was provided before crossing to the other arm. Firefighters completed a baseline skin blood-flow assessment via laser Doppler flowmetry; skin was heated to 44°C to achieve maximal cutaneous vasodilation. Skin blood flow was measured before and after exercise in a hot room, and at 0 minutes, 10 minutes, 20 minutes, and 30 minutes of recovery under temperature conditions (25.3 ± 1.2°C, 40.3 ± 13.7% RH). Platelet clotting time was assessed before drug administration, and before and after exercise.
  
  
  RESULTS
  Fifteen firefighters completed the study. Aspirin increased clotting time before and after exercise compared with placebo (p = 0.003). There were no differences in absolute skin blood flow between groups (p = 0.35). Following exercise, cutaneous vascular conductance (CVC) was 85 ± 42% of maximum in the aspirin and 76 ± 37% in the placebo groups. The percentage of maximal CVC did not differ by treatment before or after recovery. Neither maximal core body temperature nor heart rate responses to exercise differed between trials.
  
  
  CONCLUSIONS
  There were no differences in skin blood flow during uncompensable heat stress following exercise after aspirin or placebo therapy.
authors.affiliation: Department of Exercise Physiology College of Nursing and Health Sciences, Valdosta State University, Valdosta, GA, USA; Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Serina J
authors.initials: SJ
authors.lastname: McEntire
authors.affiliation: Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, PA, USA; Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Steven E
authors.initials: SE
authors.lastname: Reis
authors.affiliation: Department of Surgery, University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: Oscar E
authors.initials: OE
authors.lastname: Suman
authors.affiliation: Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, PA, USA; Department of Exercise and Nutrition Sciences, University of Buffalo, Buffalo, NY, USA.
authors.forename: David
authors.initials: D
authors.lastname: Hostler
keywords: aspirin; exertion; firefighter; heat stress; skin blood flow