Correlation Of Heart Rate Variability With Pulmonary Function Adjusted By Smoking And Physical Activity In Healthy Adults

Background: Several studies have shown poor heart rate variability in smokers and in physically inactive subjects. However, the correlation of HRV with pulmonary function is poorly understood.

Purpose: We aimed to assess correlations between HRV and spirometric indices adjusted by the confounding effects of smoking and physical activity in daily life.

Methods: We assessed forced vital capacity (FVC) and forced expiratory volume in the 1st second (FEV1) in a sample of 62 adults (38 ± 14 years; 45 men). Time and frequency domains of HRV were assessed during 10 minutes of rest in supine position. The intermediate 5 minutes of the entire RR monitoring was filtered and analyzed. Participants wore an activity monitor (Actigraph GT3x+) for seven days. Physical inactivity was defined as less than 150 min.wk-1 of moderate to vigorous physical activity in daily life. Steps/day was also quantified. Spearman correlation coefficients were calculated and multiple regression analysis adjusted by age, sex, body mass index, smoking and physical inactivity were fitted to assess the influence of HRV indices on spirometric indices.

Results: Sixteen percent of the participants were smokers and 20% were physically inactive in daily life. We observed several moderate significant correlations of FVC and FEV1 with HRV indices. The main correlations were respectively with standard deviation of RR intervals (r = 0.33 and 0.35), low-frequency (LF) (r = 0.40 and 0.38), and SD2 long-term variability in the Poincaré plot (r = 0.34 and 0.33). After multiple regression analysis, LF and physical inactivity remained as significant predictors of FVC (R2 = 0.18) and only smoking was selected as significant predictor of FEV1 (R2= 0.17).

Conclusions: We may conclude that autonomic modulation is a moderate but significant independent predictor of pulmonary function in healthy adults.

Supported by FAPESP