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The effect of obesity on heart rate variability in healthy subjects

Authors:Mitko Gospodinov, Evgeniya Gospodinova
Int J Biol Med Res. 2017; 8(4): 6153-6157  |  PDF File

Abstract

Aim: The present study was designed to show the effect of obesity on Heart Rate Variability (HRV) in healthy people. Methods: The study included 30 healthy adults, which were divided in 2 groups depending on the Body Mass Index (BMI) given by the World Health Organization (WHO) classification: control group with BMI [18.5-24.9 kg/m2] and obese group with BMI [30-34.9 kg/m2]. For HRV analysis are used linear (time-domain, frequency-domain) and non-linear (Poincaré plot, Rescaled Adjusted Range Statistics plot-R/S and Detrended Fluctuation Analysis-DFA) methods. Results: The statistical time-domain indices of HRV such as SDNN (p<0.0001), RMSSD (p<0.0001) and pNN50% (p<0.0001) in obese group were significantly decreased when compared to control group. The time-domain geometrical HRV parameters, such as HRVi (p=0.001) and TINN (p=0.007) also were decreased in obese group. The frequency-domain analysis of HRV, indicating significant decrease of low frequencies (LF, p=0.002) and high frequencies (HF, p<0.0001) in obese patients compared with controls. The ratio LF/HF (p<0.0001) was significantly higher in obese group. The analysis of the fractal properties of the heart rate, using the DFA method, showed that the alpha1 values (p<0.05) were significantly higher in obese people, but no statistically significant difference between obesity group and controls regarding the alpha2 values (p=0.2). In the R/S analysis, a significant increase in the Hurst exponent was observed in obesity subjects compared with control group (p<0.0001). The SD1 index (p<0.05), obtained from the Poincare plot was significantly lower in obesity subjects compared with control group, while the SD2 index (p=0.9) presented no statistically significant difference between groups. Conclusions: The obtained results show that reducing of HRV in the obese people, characterized by decreased parasympathetic (vagal) tone and increased sympathetic activity can lead to cardiovascular disease even to death.