Comparative impact of body shape index and body mass index on heart rate variability in healthy young adults: A 24-hour electrocardiographic analysis.

AIMS: We aimed to investigate the relationship between heart rate variability (HRV) and two anthropometric obesity parameters among young adults, including body shape index (ABSI) and body mass index (BMI).

METHODS

We included 215 asymptomatic individuals aged 18-40 years who presented for routine health screening and had no history of structural heart disease or chronic illness. Anthropometric measurements and time-domain HRV parameters (SDNN, SDNN index, rMSSD, pNN50%) were recorded through 24-h ECG monitoring. Participants were divided into ABSI and BMI categories: low-moderate ABSI (≤ 0.079), high ABSI (> 0.079), BMI < 30 kg/m2, and BMI ≥ 30 kg/m2. The study parameters were compared between the groups.

RESULTS

67% of the study participants were female, and the mean age was 28.5 ± 8. We found a relationship between waist circumference, BMI, and certain HRV parameters. However, all investigated time-domain HRV parameters were similar between the ABSI groups, suggesting that ABSI may not reflect autonomic function as effectively as BMI among adults aged < 40 years. Nevertheless, the SDNN, SDNN index, rMSSD, and pNN50% values were significantly lower in the BMI ≥ 30 group than in the BMI < 30 group (p < 0.05). Linear regression analysis revealed significant inverse associations between BMI and all time-domain HRV parameters; however, no significant association was observed between ABSI and any time-domain HRV parameter.

CONCLUSIONS

Waist circumference and BMI are inversely related to HRV parameters in young adults. The absence of this association with ABSI suggests that BMI remains a more relevant anthropometric measure of cardiac autonomic modulation in this population.