Spirometric Parameters Are Associated with Cardiovascular Autonomic Reactivity in Healthy Medical Students

Abstract

Background: The autonomic nervous system and respiratory system are closely interconnected; however, the association between cardiovascular autonomic reactivity and pulmonary function in healthy young adults remains insufficiently characterized. Understanding this relationship may provide insight into early cardiorespiratory integration before disease onset.

Methods: This cross-sectional study included 52 healthy medical students (mean age 23.4 ± 2.8 years). Spirometry assessed forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), and FEV₁/FVC ratio. Cardiovascular autonomic reactivity was evaluated using the deep breathing test (expiration–inspiration difference), active standing test (ΔHR₆₀), and isometric handgrip test (ΔSBP). Correlation and multivariate regression analyses were performed adjusting for sex, perceived stress, sleep duration, BMI, and smoking status.

Results: All participants demonstrated normal spirometric and autonomic values. FEV₁ and FVC showed strong positive correlations with parasympathetic reactivity and sympathetic pressor response, while ΔHR₆₀ was moderately and inversely associated with lung volumes. In multivariate models, FEV₁ independently predicted parasympathetic reactivity (β = 0.51, p < 0.001), and FVC independently predicted sympathetic pressor response (β = 0.47, p < 0.001). Male sex and longer sleep duration were associated with greater parasympathetic activity, whereas higher perceived stress correlated with reduced vagal tone.

Conclusion: Pulmonary function is independently associated with cardiovascular autonomic reactivity in healthy young adults, demonstrating robust physiological cardiorespiratory coupling within normal ranges.

Novelty: This study demonstrates that subtle variations in normal spirometric parameters are significantly associated with autonomic cardiovascular reflexes in healthy medical students, highlighting spirometry as a potential early marker of autonomic balance in high-stress populations.