# Sleep Quality and Cardiopulmonary Responses During Exercise Testing: Exploring the Chronotropic and Ventilatory Response Relationship with Sleep Quality in Healthy Young Men: A Cross-Sectional Study

## TL;DR

This study found that poor sleep quality in young men is linked to reduced ventilatory responses during exercise, suggesting the importance of sleep in exercise performance.

## Contribution

The study explores the novel relationship between sleep quality and specific cardiopulmonary responses during exercise in healthy young men.

## Key findings

- Poor sleep quality correlated with lower chronotropic and ventilatory responses during exercise testing.
- After adjusting for age and body metrics, only expired oxygen levels remained significantly associated with sleep quality.
- Good sleepers showed higher tidal volume and expired gas ratios compared to poor sleepers.

## Abstract

Background: Sleep quality is critical to health, and its disturbances may affect multiple systems, including autonomic and respiratory regulation. However, its relationship with chronotropic and ventilatory responses in healthy young men remains underexplored. Thus, the study aimed to investigate the relationship between sleep quality, as measured by the Pittsburgh Sleep Quality Index (PSQI), and chronotropic and ventilatory responses during cardiopulmonary exercise testing (CPET) in a healthy young male population and to explore group differences between good and poor sleepers. Methods: Thirty-three healthy men completed the PSQI and a graded CPET with breath-by-breath gas analysis. Pearson correlation was used to examine relationships between the PSQI and CPET outcomes: chronotropic response (%), tidal volume (VT), minute ventilation (VE), VO2, VCO2, expired O2/CO2, VE/VO2, and VE/VCO2. After accounting for age, height, and weight, the correlation was reassessed. Secondary analyses using a standard cut-off point compared good (PSQI < 5) vs. poor sleepers (PSQI ≥ 5) with Welch’s t-tests. Results: Participants were predominantly poor sleepers (84.8%; PSQI 7.3 ± 3.2). A higher PSQI correlated with lower chronotropic response (r = −0.35, p = 0.04), lower VT (r = −0.42, p = 0.02), lower expired O2 (r = −0.46, p = 0.01), and lower expired CO2 (r = −0.33, p = 0.05). Associations with VE, VO2, VCO2, VE/VO2, and VE/VCO2 were small and non-significant (p > 0.05). When age, height, and weight were controlled for, the attenuated chronotropic response association with the PSQI was not significant; however, the PSQI association remained significant for expired O2 (r = −0.32, p = 0.04), with a trend for VT. In group comparisons, chronotropic response was higher but not significant; good sleepers showed higher VT and greater expired O2/CO2 (p < 0.05). Conclusions: Poorer sleep quality was initially associated with multiple cardiopulmonary responses at peak during CPET. However, after controlling for age and anthropometry measures, only expired O2 remained linked. The findings suggest that routine sleep quality screening may add interpretive value to CPET by flagging individuals with reduced ventilatory depth, warranting prospective studies to test whether improving sleep quality can enhance exercise responses.