Abstract
Our study has assessed the effect of aerobic physical training on the heart rate variability (HRV) on sedentary women with different body mass indices (BMI; weight/height2). Forty-eight volunteers were divided into three groups according to their BMI as follows: NW group (normal weight), 18.0-24.9; OW group (overweight), 25.0-29.9; and OB group (obese), 30.0-39.9. HRV was assessed with the subjects at rest and during tilt test by means of spectral analysis before and after 16 weeks of an aerobic physical training protocol. Prior to the aerobic physical training, OW and OB groups exhibited decrease in low frequency (LF, 0.4-0.15 Hz) and high frequency (HF, 0.15-0.5 Hz). After aerobic physical training all groups had similar HF oscillations, with only OB group exhibiting increase in LF oscillations. The HRV responses to tilt test obtained before and after aerobic physical training showed that NW group had no differences in LF (34 ± 6% vs. 36 ± 8%) and HF (-65 ± 6% vs. -60 ± 7%) oscillations. However, OW group had an increase in LF (46 ± 6% vs. 86 ± 14%) and HF (-44 ± 7% vs.-61 ± 7%) oscillations, whereas OB group had a decrease in LF (288 ± 25% vs. 159 ± 16%) and HF (-83 ± 5 vs. -70 ± 4%) oscillations. In conclusion, our results suggest that the increase in the percentage of body fat may impair the cardiac autonomic modulation in proportion to BMI, which is an important predictor of cardiovascular morbidity and mortality. In turn, the physical exercise can attenuate this negative effect, regardless of the reduction of body fat mass.
Highlights
Obesity is normally associated to the metabolic perturbations and it can be accompanied by cardiovascular autonomic dysfunctions [1]
The present study has shown that overweight and obese sedentary women had changes in heart rate variability (HRV) modulation, characterized by concomitant reduction in LF and high frequencies (HF) oscillations
The main finding of this study was that aerobic physical training have induced HF oscillations in obese and overweight women, whose values were similar to those of normal weight women
Summary
Obesity is normally associated to the metabolic perturbations and it can be accompanied by cardiovascular autonomic dysfunctions [1] In this sense, analysis of the autonomic modulation of heart rate variability (HRV) has demonstrated that excess in body fat mass might promote concomitant reduction of LF and HF oscillations, characterizing low autonomic sympathetic and parasympathetic cardiac influences and increasing the risk of cardiac morbidity and mortality [2,3,4,5,6,7]. Obesity and overweight have a relevant impact on longevity, and any kind of intervention aiming to reduce the body fat percentage yields long-term benefits that trend to be greater with earlier intervention [8] By this reason the main recommendations regarding programs for reduction of body fat percentage are the following: reduction of energetic support, decrease in dietary fat ratio, and practice of physical training [9]. Some studies have shown evidence that improvement in cardiovascular autonomic control from physical training would be one of the main adaptations, playing a positive role in energetic balance related to obesity subjects [2,13]
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