Evaluation of Heart Rate Reserve and Exercise Capacity in Individuals with and without Metabolic Syndrome

Introduction: Heart rate progressively increases with exercise through the function ofsympathetic and parasympathetic nerves. These nerves control the performance of sinoatrialnode. Lack of heart rate increase proportionate to the exercise is associated with poor prognosis.Moreover, exercise capacity (EC) is considered as a predictor of cardiac events. The currentstudy compares these two indices in individuals with and without metabolic syndrome in Isfahan.
Methods: The study was performed on 203 people without metabolic syndrome and 123 patients with metabolic syndrome registered in the Isfahan Cohort Study. The demographic data,
abdominal circumference, blood pressure, height, and weight of the participants were recorded. Moreover, the serum triglyceride, fasting blood sugar, total cholesterol, high density lipoprotein (HDL), and low density lipoprotein (LDL)levels were measured. Exercise test was carried out according to the Bruce standard protocol and heart rate reserve (HRR) and exercise capacity
(EC) were determined and recorded. The age-adjusted data were analyzed using SPSS software, version 15, by the generalized linear model.
Findings: The two groups were not significantly different with regard to HRR (p= 0.27). The level of EC in the metabolic syndrome group was significantly lower than that observed in the group without metabolic syndrome (p= 0.022).
Conclusion: We could not find relationship between HRR and metabolic syndrome or lack of the syndrome. However, the relationship between metabolic syndrome and the EC level indicates that in individuals with metabolic syndrome, when EC decreased, HRR did not change significantly.
Keywords: Metabolic syndrome, Exercise test, Heart rate reserve, Insulin resistance.