Background: Low heart rate recovery (HRR) at exercise test and the metabolic syndrome (MetS) are both predictors of cardiovascular morbidity and mortality. We studied in 75-year-old women and men, representative of the general population, the relationship between (1) HRR and the MetS, (2) HRR and the individual components of the MetS, and (3) HRR and insulin sensitivity.
Methods: A cross-sectional study of randomly selected 75-year-olds from a general population was performed (191 women and 194 men). The MetS was defined according to the National Cholesterol Education Program criteria. Heart rate was measured as beats per minute immediately after exercise and at 4 minutes into recovery.
Results: Heart rate recovery (median and interquartile range, beat/min) was 48 (37-58) for women and 49 (38-58) for men. Thirty-seven percent of the women and 25% of the men had the MetS. Heart rate recovery was 52 (42-61) for women with the MetS and 42 (31-49) for those without. The corresponding values for men was 50 (39-61) and 47 (35-54); the difference between individuals with and without the MetS was significant for women (P < .001) but not for men (P = .084). The following significant correlation coefficients between HRR and MetS components were found: for women, waist circumference (-0.43, P < .001), high-density lipoprotein cholesterol (0.37, P < .001), insulin sensitivity (-0.37, P < .001), fasting plasma glucose (-0.30, P < .001), and triglycerides (-0.24, P = .001); for men, triglycerides (-0.20, P = .005). The sex disparity in the strength of correlation reached statistical significance for insulin sensitivity (P < .001) and waist circumference (P = .042).
Conclusion: Among 75-year-olds, the MetS and related components are more strongly correlated to HRR in women than in men.