Is the abdominal subcutaneous fat a predictor of heart rate variability in men with low metabolic risk?

Abstract

Objective: To measure the type and strength of the potential association between heart rate variability at rest and some indicators of adiposity in young, lean, and physically active men. Introduction: Although overweight/obesity, increased adiposity and physical inactivity are associated with decreased heart rate variability and autonomic dysregulation, the relationship between these factors has not been explored in detail in subjects with low metabolic risk: normal weight, low adiposity and physically active. Methodology: Cross-sectional analytical study. The spectral components of heart rate variability were analyzed in 24 physically active men, 18-30 years old, with normal weight and adiposity. Multiple linear regression analysis was performed to explain heart rate variability as a function of waist to hip ratio, abdominal skinfod and physical activity. Results: The volume of weekly physical activity was positively related to RMSSD and HF, and negatively with LF and LF/HF. Both the waist to hip ratio and abdominal skinfold were positively related with HF, and negatively with LF and LF/HF. In all cases, the B regression standardized coefficients were between 0.395 and 0.505 (p<0.05). The visceral fat rating calculated from bioimpedance showed no relation. Conclusions: The findings reported here are indicative that in young, lean and physically active men, physical activity and subcutaneous fat are positively related to vagal tone and negatively with sympathetic tone. This leads us to postulate that the accumulation of caloric excess in the form of subcutaneous adipose tissue (not visceral) might be a protective mechanism against the development of metabolic syndrome in these subjects.