Resting heart rate, heart rate reserve, and metabolic syndrome in professional firefighters: A cross-sectional study

BackgroundLittle is known about the associations of resting heart rate (RHR) and heart rate reserve (HRR) with metabolic syndrome (MetS) in firefighters. MethodsFor each of 288 professional firefighters, HRR was calculated as the difference between measured RHR and estimated maximum HR. For comparison, VO2 max based on a treadmill test was included. MetS was defined according to the NCEP/ATP III criteria. ResultsThe prevalence of MetS was 14.2%. The average of RHR was 61.5 beat/min. Only 5.8% of the firefighters had RHR of 80 beat/min. Between the firefighters in the lowest and highest quintiles, the prevalence ratios (95% confidence intervals) for MetS were 1.88 (0.71-4.94), 5.90 (1.74-20.02), and 8.03 (1.86-34.75) for RHR, HRR, and VO2 max, respectively. Both HRR and VO2 max, but not RHR, were significantly associated with MetS and its most component risk factors in middle-aged firefighters. ConclusionsHRR, a simple cardiovascular fitness measure, was inversely associated with MetS among middle-aged professional firefighters.