A body shape index: a potentially unreliable measure for assessing heart rate variability in healthy adults under forty

Objectives While obesity is recognizably associated with changes in heart rate variability (HRV), the association between body composition and HRV is less evident in healthy people. We aimed to investigate the relationship between HRV and two anthropometric obesity parameters in healthy adults under forty, including a body shape index (ABSI) and body mass index (BMI). Methods We included 215 individuals with no known disease aged 18–40, recording anthropometric measurements and time-domain HRV parameters (SDNN, SDNN index, rMSSD, pNN50) through 24-hour ECG Holter monitoring. Participants were divided into the ABSI and BMI categories, as low ABSI, high ABSI, BMI<30 kg/m2, and BMI ≥ 30 kg/m2. We compared the study parameters among the groups. Results 67% of the study participants were female, and the mean age was 28.5±8. We found a strong relationship between waist circumstance, BMI, and certain HRV parameters. However, all investigated time-domain HRV parameters were similar among low and high ABSI groups, suggesting that ABSI may not reflect autonomic function as effectively as BMI in healthy adults under forty. Nevertheless, SDNN, SDNN index, rMSSD, and pNN50 values were statistically significantly lower in the BMI≥30 groups than in the BMI<30 group. Conclusions Waist circumstance and BMI appear inversely associated with HRV-related autonomic function in young, healthy adults, while ABSI lacks this association.