title: Inflammatory responses of older firefighters to intermittent exercise in the heat.
abstract: OBJECTIVE
  Repeated strenuous work in the heat may predispose firefighters to augmented immune responses and inflammation. This study examined the immune responses in 12 older Firefighters (FF) and 12 older Non-Firefighters (Non-FF), and a group of 6 young FF and 6 young Non-FF, following intermittent exercise in the heat.
  
  
  METHODS
  The participants, matched for age, body surface area, body composition, and VO(2peak), cycled 4 × 15 min at moderate-to-high heat production (400 W), each followed by 15-min rest, in dry [10-20% relative humidity (RH)] and humid (60% RH) heat (35 °C). Rectal temperature (T(re)) and heart rate (HR) were measured continuously, and blood samples at baseline (PRE) and following 60-min recovery (POST) were analyzed for Interleukin (IL)-6, Tumor Necrosis Factor (TNF-α), C-reactive protein (CRP), platelet count (PLT), and mean platelet volume (MPV).
  
  
  RESULTS
  No differences were observed for T(re), HR, TNF-α, CRP, or PLT between the FF and Non-FF in either condition. The Non-FF had greater changes in IL-6 (Warm/Dry = +1.10 ± 0.18, Warm/Humid = +2.94 ± 0.74 pg mL(-1)), compared to the FF (Warm/Dry = +0.67 ± 0.17, Warm/Humid = +0.70 ± 0.33 pg mL(-1)), and MPV at PRE/POST compared to the FF. Between the young and older FF and Non-FF, no differences in T(re), HR, PLT, or MPV were observed, however, elevated CRP (Warm/Dry) in the older FF, and IL-6 (Warm/Dry) and TNF-α (both conditions) in the older Non-FF, were observed.
  
  
  CONCLUSIONS
  The elevated IL-6 in the Non-FF is potentially indicative of increased strain in the Non-FF and/or adaptive changes in the FF due to the occupational demands.
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics 125 University Private, University of Ottawa, Montpetit Hall, Room 367, Ottawa, Ontario, K1N 6N5, Canada.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Wright-Beatty
authors.forename: Tom M
authors.initials: TM
authors.lastname: McLellan
authors.forename: Joanie
authors.initials: J
authors.lastname: Larose
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Sigal
authors.forename: Pierre
authors.initials: P
authors.lastname: Boulay
authors.forename: Glen P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D000328:Adult; D000367:Age Factors; D001831:Body Temperature; D002097:C-Reactive Protein / Q000378:metabolism; D016022:Case-Control Studies; D015444:Exercise; D061388:Firefighters; D006339:Heart Rate; D018869:Heat-Shock Response; D006358:Hot Temperature; D006801:Humans; D007249:Inflammation / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D022722:Thermogenesis; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein