J Cardiopulm Rehabil Prev 2021 05;41(3):199-201
Department of Sport Science, University of Seoul, Seoul, South Korea (Dr Jae); Department of Exercise Science, Syracuse University, Syracuse, New York (Dr Heffernan); Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland (Drs Kurl and Laukkanen); National Institute for Health Research Bristol Biomedical Research Centre, University Hospitals Bristol and Weston NHS Foundation Trust and the University of Bristol, and Translational Health Sciences, Bristol Medical School, University of Bristol, Southmead Hospital, Bristol, England (Dr Kunutsor); Department of Cardiovascular Disease, Mayo Clinic, Rochester, Minnesota (Drs Kim and Johnson); Preventive Cardiology and Cardiac Rehabilitation, Beaumont Health, Royal Oak, Michigan (Dr Franklin); and Institute of Clinical Medicine, Department of Medicine, University of Eastern Finland, Kuopio, and Central Finland Health Care District Hospital District, Department of Medicine, Jyväskylä, Finland District, Jyväskylä, Finland (Dr Laukkanen).
Introduction: Both inflammation and cardiorespiratory fitness (CRF) are associated with the risk of respiratory infections. To clarify the hypothesis that CRF attenuates the incident risk of pneumonia due to inflammation, we conducted a prospective study examining the independent and joint associations of inflammation and CRF on the risk of pneumonia in a population sample of 2041 middle-aged men.
Methods: Cardiorespiratory fitness was directly measured as peak oxygen uptake (V˙o2peak) during progressive exercise testing to volitional fatigue, and categorized into tertiles. Inflammation was defined by high-sensitivity C-reactive protein (hsCRP). Pneumonia cases were identified by internal medicine physicians using the International Classification of Diseases codes in clinical practice.
Results: During a median follow-up of 27 yr, 432 pneumonia cases were recorded. High hsCRP and CRF were associated with a higher risk (HR = 1.38; 95% CI, 1.02-1.88) and a lower risk of pneumonia (HR = 0.55; CI, 0.39-0.76) after adjusting for potential confounders, respectively. Compared with normal hsCRP-Fit, moderate to high hsCRP-Unfit had an increased risk of pneumonia (HR = 1.63; CI, 1.21-2.20), but moderate to high hsCRP-Fit was not associated with an increased risk of pneumonia (HR = 1.25; CI, 0.93-1.68).
Conclusions: High CRF attenuates the increased risk of pneumonia due to inflammation. These findings have potential implications for the prevention of respiratory infection characterized by systemic inflammation, such as coronavirus disease-2019 (COVID-19).