A longitudinal study conducted on U.S. adults has demonstrated that meeting weekly exercise guidelines is associated with a decreased risk of mortality from pneumonia and influenza. Bryant Webber, MD, MPH, and colleagues from the Division of Nutrition, Physical Activity, and Obesity at the CDC in Atlanta reported that individuals who met both aerobic physical activity and muscle-strengthening activity guidelines experienced a 48% lower adjusted risk of pneumonia and influenza-related death over a median follow-up period of 9.2 years compared to those who met neither (HR 0.52, 95% CI 0.39-0.68).
The researchers noted that this protective association, supported by plausible biological mechanisms and consistent with previous studies, may necessitate additional clinical and public health efforts to reduce the prevalence of inadequate muscle-strengthening activity and aerobic inactivity. However, the study also revealed potential benefits associated with aerobic activity levels below the guideline recommendations, as well as potential harm at the highest levels of strength training.
According to guidelines from the Department of Health and Human Services, adults should engage in at least 150 minutes of moderate-intensity equivalent aerobic physical activity per week, along with two or more episodes of strength training. The study found that adults who engaged in 10 to 149 minutes of moderate- to vigorous-intensity physical activity per week experienced a significantly 21% lower risk of pneumonia and influenza mortality compared to inactive individuals. The benefit peaked with a 50% risk reduction for those engaging in 301 to 600 minutes of weekly activity, with no further risk reduction observed for those who exceeded 600 minutes of activity.
Regarding muscle-strengthening activities, participants who reported engaging in two episodes per week had a 47% lower risk of mortality from influenza and pneumonia compared to those who engaged in fewer than two episodes. However, engaging in seven or more episodes per week was associated with a 41% higher risk of mortality.
The study revealed that only 19% of the more than 500,000 participants met both weekly targets, while 51% met neither. Overall, individuals who met the aerobic activity guidelines had a 36% lower adjusted mortality risk from influenza and pneumonia compared to inactive individuals (HR 0.64, 95% CI 0.54-0.76). Meeting the muscle-strengthening guidelines did not show a significant difference in mortality risk.
Webber and colleagues noted that the reduced mortality risk observed in individuals who met the exercise guidelines is likely due to exercise’s positive impact on various health conditions and the strengthening of immune responses. They highlighted that physical activity is associated with lower incidence of comorbidities such as stroke and coronary heart disease, which increase mortality risk among adults with community-acquired pneumonia. Clinical trials have also demonstrated improvements in expectoration among individuals with cystic fibrosis and peak oxygen uptake in those with chronic obstructive pulmonary disease (COPD) following aerobic training programs.
The results of this study build upon previous findings that demonstrated the benefits of exercise in individuals following pulmonary embolism and may indicate cardiorespiratory benefits for patients undergoing chemotherapy.
The cohort study included 577,909 adults who participated in the National Health Interview Survey from 1998 to 2018 and were followed for a median of 9.23 years. Of the participants, 52.2% were women, and 69.2% were white. The participants were classified into five volume-based categories based on self-reported aerobic and muscle-strengthening activity.
The researchers acknowledged potential limitations, including the exclusion of physical activity episodes shorter than 10 minutes, potential gaps in mortality data, the possibility of underlying health conditions influencing changes in physical activity levels, and other factors that may have influenced the study’s results.