Shortened Recovery Period Between Firefighting Work Bouts Increases Cardiac Response Disproportionately With Metabolic Rate.

Abstract

To compare physiological responses between two firefighting simulations with different recovery periods, one having work bouts intercalated by a shortened recovery period. Thirteen male firefighters participated in two different simulations, which comprised two identical 25-minute effort bouts (E1 and E2) intercalated by a recovery period of either 20 (T20) or 5 (T5) minutes. From E1 to E2, the increase of mean heart rate (HR) (26 ± 5 vs 14 ± 5 bpm, P < 0.001) and mean VO2 (1.8 ± 0.4 vs 1.3 ± 0.4 mL kg min, P < 0.001) was higher in T5 than in T20. Results indicate that a shortened recovery time between firefighting work bouts intensifies cardiac strain disproportionately with metabolic rate, since mean HR increased by 19.3% and 10.8% while mean VO2 increased by only 7.2% and 5.0% in T5 and T20, respectively.