Purpose: The objective of this study is to assess prospectively the dose-response relationship between respiratory disease (ICD10: J1-99), pneumonia (ICD10: J12.0-18.9), and aspiration pneumonia mortality (ICD10: J69) versus baseline walking and running energy expenditure (MET · h · d(-1), 1 MET = 3.5 mL O2 · kg(-1) · min(-1)).
Methods: We conducted Cox proportional hazard analyses of 109,352 runners and 40,798 walkers adjusted for age, sex, smoking, diet, alcohol, and education.
Results: There were 236 deaths with respiratory disease listed as the underlying cause, and 833 deaths were respiratory disease related (entity axis diagnosis). Included among these were 79 deaths with pneumonia listed as the underlying cause and 316 pneumonia-related deaths, and 77 deaths were due to aspiration pneumonia. There was no significant difference in the effect of running compared with walking (per MET-hour per day) on mortality; thus, runners and walkers were combined for analysis. Respiratory disease mortality decreased 7.9% per MET-hour per day as the underlying cause (95% CI, 1.6%-14.0%; P = 0.01) and 7.3% for all respiratory disease-related deaths (95% CI, 4.2%-10.4%; P = 10(-5)). Pneumonia mortality decreased 13.1% per MET-hour per day as the underlying cause (95% CI, 2.6%-23.2%; P = 0.01) and 10.5% per MET-hour per day for all pneumonia-related deaths (95% CI, 5.4%-15.5%; P = 0.0001). The risk for aspiration pneumonia mortality also did not differ between running and walking, and it decreased 19.9% per MET-hour per day run or walked (95% CI, 8.9%-30.2%; P = 0.0004). These results remained significant when additionally adjusted for body mass index.
Conclusions: Higher doses of running and walking were associated with lower risk of respiratory disease, pneumonia, and aspiration pneumonia mortality in a dose-dependent manner, and the effects of running and walking appear equivalent. These effects appear to be independent of the effects of exercise on cardiovascular disease.