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.
Yide Wang, Hongxia Duan, Yingqi Wang and 7 others
PMID 40524454WHAT IT FOUND
Higher weekly physical activity was linked to lower all-cause mortality overall.
The pattern varied by airflow limitation: normal and mild groups showed lower risk below thresholds, the moderate group showed higher risk above 63.42 MET-h/week, and severe or very severe groups showed no clear association.
Key findings
01Across the whole cohort, a higher physical activity dose was associated with lower all-cause mortality; the paper reports a 12% lower risk for each 1 standard deviation increase in MET hours per week (hazard ratio 0.88).
02For normal and GOLD 1 airflow limitation, mortality risk was lower below thresholds of 41.50 and 13.21 MET hours per week, with reported hazard ratios of 0.66 and 0.41.
03For GOLD 2 airflow limitation, activity below 63.42 MET hours per week was linked to lower mortality, while activity above it was linked to higher mortality; GOLD 3-4 showed no clear association.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
This was an observational cohort, not a randomised trial, so it cannot show that exercise caused lower mortality. The outcome was all-cause mortality only, so it does not show whether deaths were due to respiratory disease. The sample was drawn from one rural region in Northwest China, so the results may not apply to other populations. The GOLD 2 and GOLD 3-4 subgroups had limited sample sizes, so their threshold estimates are less stable. Physical activity was measured as total MET hours per week, not by exercise type, frequency, or duration, so it cannot guide specific training content. Physical activity was collected by questionnaire, so recall and reporting errors are possible.
Declared interests
The authors declared no conflicts of interest. The study was funded by the National Natural Science Foundation of China and a Shanghai Municipal Health Commission discipline leader project.
The easy way to misread this
Do not read these results as proof that exercise lowers mortality. This was an observational cohort, not a trial. Also, do not use the 63.42 MET-h/week threshold as a prescription; it came from a subgroup analysis with limited sample size.