# DIFFERENTIAL PATTERNS OF THE RELATIONSHIP BETWEEN EXERCISE DOSE AND MORTALITY RISK ACROSS SEVERITIES OF AIRFLOW LIMITATION: A PROSPECTIVE COHORT STUDY WITH A 5-YEAR FOLLOW-UP PERIOD

## TL;DR

Moderate exercise reduces mortality risk in people with normal or mild lung function, but too much exercise may be harmful for those with severe lung conditions.

## Contribution

The study identifies specific physical activity thresholds that reduce mortality risk in individuals with varying degrees of airflow limitation.

## Key findings

- Moderate physical activity (41.50 MET·h/week) reduces mortality risk in individuals with normal lung function.
- Exceeding the physical activity threshold in GOLD 2 is associated with increased mortality risk.
- No significant association between physical activity and mortality was found in GOLD 3–4.

## Abstract

This study examines the dose–response relationship between physical activity (PA) and all-cause mortality across different severities of airflow limitation, identifying threshold effects that yield new insights into the PA–mortality association.

A prospective cohort study with a 5-year follow-up (2018–2023), employing multivariate Cox models and penalized spline smoothing to assess non-linear associations.

A total of 2,975 individuals from a cohort categorized by airflow limitation severity (normal, GOLD 1–4).

PA levels were quantified in metabolic equivalent hours per week (MET·h/week). Cox proportional hazards models were used to evaluate PA–mortality associations, with penalized spline analysis detecting threshold effects.

Identified thresholds were 41.50 MET·h/week (95% CI: 23.03–64.22) for normal lung function and 13.21 MET·h/week (95% CI: 9.67–16.14) for GOLD 1. Below these thresholds, higher PA levels were associated with a significant reduction in mortality risk (HR = 0.66, HR = 0.41, respectively). In GOLD 2, PA levels below the threshold were associated with a lower mortality risk (HR=0.85), whereas PA exceeding the threshold was associated with a higher mortality risk (HR = 1.23). No significant associations were observed in GOLD 3–4.

PA demonstrates a non-linear, threshold-dependent association with mortality. These findings underscore the importance of individualized PA recommendations for optimizing health outcomes in individuals with chronic respiratory conditions.

Many people with chronic lung conditions struggle with breathing problems, which can affect their daily lives and overall health. Regular physical activity is known to improve lung function and reduce the risk of complications, but how much exercise is beneficial remains unclear. Our study followed a large group of individuals over 5 years to examine how different levels of physical activity impact survival rates, especially in those with varying degrees of airflow limitation. We found that moderate exercise was associated with a lower risk of death among individuals with normal lung function or mild impairment. However, too much exercise may not be beneficial for those with more severe lung conditions. These findings highlight the need for personalized exercise recommendations based on lung health. By tailoring physical activity levels to individual needs, healthcare providers can help patients improve their quality of life and reduce health risks associated with lung diseases like COPD.