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Can Exercise Prevent the Common Cold?

      Inflammation contributes to atherosclerotic coronary artery disease risk. Physical exercise reduces the incidence of coronary artery disease,
      • Thompson P.D.
      • Buchner D.
      • Pina I.L.
      • et al.
      Exercise and physical activity in the prevention and treatment of atherosclerotic cardiovascular disease: a statement from the Council on Clinical Cardiology (Subcommittee on Exercise, Rehabilitation, and Prevention) and the Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity).
      an effect generally attributed to changes in coronary artery disease risk factors, but exercise might also reduce coronary artery disease risk by reducing inflammation.
      • Kasapis C.
      • Thompson P.D.
      The effects of physical activity on serum C-reactive protein and inflammatory markers: a systematic review.
      Vigorous exercise transiently increases C-reactive protein (CRP), interleukin 1 & 6, and tumor necrosis factor,
      • Kasapis C.
      • Thompson P.D.
      The effects of physical activity on serum C-reactive protein and inflammatory markers: a systematic review.
      whereas chronic exercise training appears to reduce inflammatory markers including CRP. These changes may be directly related to muscle contraction because interleukin 6, a primary stimulant of hepatic CRP production, is released from skeletal muscle during physical activity.
      • Steensberg A.
      • Dalsgaard M.K.
      • Secher N.H.
      • Pedersen B.K.
      Cerebrospinal fluid IL-6, HSP72, and TNF-alpha in exercising humans.
      Exercise-related inflammatory and immune responses also may affect susceptibility to other illness in a dose-dependent or “J-shaped curve” relationship.
      • Nieman D.C.
      • Nehlsen-Cannarella S.L.
      • Markoff P.A.
      • et al.
      The effects of moderate exercise training on natural killer cells and acute upper respiratory tract infections.
      Low exercise doses appear to increase disease resistance, whereas high exercise doses might increase disease susceptibility.
      In this issue of The American Journal of Medicine, Chubak et al report the effect of moderate intensity exercise training on the occurrence of upper respiratory infections.
      • Chubak J.
      • McTiernan A.
      • Sorensen B.
      • et al.
      Moderate-intensity exercise reduces the incidence of colds among postmenopausal women.
      These authors randomly assigned 115 overweight and obese postmenopausal women to either aerobic exercise training or stretching control groups. The groups were similar, but unfortunately more of the controls were immunized against influenza both before and during the protocol. The risk of colds during the year of the study decreased in the exercisers, and this risk was 3-fold higher in the stretching group over the final 3 months of the study.
      This is great news because we all know the misery of the common cold, but is the news too good to be true? That is difficult to judge for several reasons duly noted by the authors. First, the diagnosis of upper respiratory infections was based on self-administered questionnaires. The questionnaires had good reproducibility, but the definition of “cold,” as well as data validating the clinical accuracy of self-reported symptoms were not provided. Second, although colds were reduced, there was no reduction in the total upper respiratory infections. This raises the possibility that subjects reclassified their symptoms from upper respiratory infections to colds. Third, the difference between the exercise group and stretching controls was due to both a decrease in colds among the exercisers and an increase among the controls. Is it possible that the stretchers infected each other during the stretching sessions?
      These comments are not designed to disparage the present report but to highlight difficulties in such research. The present report is notable for its large population size, random assignment design, quarterly assessment of upper respiratory infection incidence, and year-long exercise-training protocol. Adherence among the exercise trainers was excellent. The results also are provocative and will be widely cited as additional evidence for the benefits of exercise. Nevertheless, because of these problems noted above, a definitive conclusion that regular exercise reduces the frequency of the common cold must await confirmatory reports.

      References

        • Thompson P.D.
        • Buchner D.
        • Pina I.L.
        • et al.
        Exercise and physical activity in the prevention and treatment of atherosclerotic cardiovascular disease: a statement from the Council on Clinical Cardiology (Subcommittee on Exercise, Rehabilitation, and Prevention) and the Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity).
        Circulation. 2003; 107: 3109-3116
        • Kasapis C.
        • Thompson P.D.
        The effects of physical activity on serum C-reactive protein and inflammatory markers: a systematic review.
        J Am Coll Cardiol. 2005; 45: 1563-1569
        • Steensberg A.
        • Dalsgaard M.K.
        • Secher N.H.
        • Pedersen B.K.
        Cerebrospinal fluid IL-6, HSP72, and TNF-alpha in exercising humans.
        Brain Behav Immun. 2006; (e-reference ahead of print)
        • Nieman D.C.
        • Nehlsen-Cannarella S.L.
        • Markoff P.A.
        • et al.
        The effects of moderate exercise training on natural killer cells and acute upper respiratory tract infections.
        Int J Sports Med. 1990; 11: 467-473
        • Chubak J.
        • McTiernan A.
        • Sorensen B.
        • et al.
        Moderate-intensity exercise reduces the incidence of colds among postmenopausal women.
        Am J Med. 2006; 119: 938-943