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Potential, but Unobserved, Adverse Cardiovascular Effects From Endurance Exercise

      To the Editor:
      The review by O'Keefe et al
      • O'Keefe J.H.
      • Patil H.R.
      • Lavie C.J.
      • Magalski A.
      • Vogel R.A.
      • McCullough P.A.
      Potential adverse cardiovascular effects from excessive endurance exercise.
      in the June 2012 issue of Mayo Clinic Proceedings discusses the hypothesis that excessive strenuous exercise may result in adverse cardiovascular effects. Data from Wen et al
      • Wen C.P.
      • Wai J.P.
      • Tsai M.K.
      • et al.
      Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study.
      are cited as supportive evidence that the mortality benefits of exercise “peak at 50 to 60 minutes of vigorous exercise per day.” The reproduced figure, however, does not show a peak; rather, it possibly shows a plateau in the benefit of exercise at the highest level observed, and even the case for a plateau is unconvincing. Turning to the primary data, O'Keefe et al wrote a letter to the journal of publication
      • O'Keefe J.H.
      • Patil H.R.
      • Lavie C.J.
      Exercise and life expectancy [letter].
      and received a response that proved their interpretation to be incorrect. Wen et al
      • Wen C.P.
      • Tsai M.K.
      • Tsai S.P.
      • et al.
      Exercise and life expectancy [reply].
      responded to their letter with a description of data that show not only the absence of peak but also no evidence of a plateau, with a continuing trend to improved all-cause mortality and even better hazard ratios for cardiovascular disease at the highest level of exercise. Wen et al wrote, “We were not able to identify an upper limit of physical activity, either moderate or vigorous, above which more harm than good will occur… .” The interpretation of the data provided in the review by O'Keefe et al is misleading, particularly given the response of the authors of the original data.

      References

        • O'Keefe J.H.
        • Patil H.R.
        • Lavie C.J.
        • Magalski A.
        • Vogel R.A.
        • McCullough P.A.
        Potential adverse cardiovascular effects from excessive endurance exercise.
        Mayo Clin Proc. 2012; 87: 587-595
        • Wen C.P.
        • Wai J.P.
        • Tsai M.K.
        • et al.
        Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study.
        Lancet. 2011; 378: 1244-1253
        • O'Keefe J.H.
        • Patil H.R.
        • Lavie C.J.
        Exercise and life expectancy [letter].
        Lancet. 2012; 379: 799
        • Wen C.P.
        • Tsai M.K.
        • Tsai S.P.
        • et al.
        Exercise and life expectancy [reply].
        Lancet. 2012; 379: 800-801

      Linked Article

      • Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise
        Mayo Clinic ProceedingsVol. 87Issue 6
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          A routine of regular exercise is highly effective for prevention and treatment of many common chronic diseases and improves cardiovascular (CV) health and longevity. However, long-term excessive endurance exercise may induce pathologic structural remodeling of the heart and large arteries. Emerging data suggest that chronic training for and competing in extreme endurance events such as marathons, ultramarathons, ironman distance triathlons, and very long distance bicycle races, can cause transient acute volume overload of the atria and right ventricle, with transient reductions in right ventricular ejection fraction and elevations of cardiac biomarkers, all of which return to normal within 1 week.
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      • In reply
        Mayo Clinic ProceedingsVol. 87Issue 11
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          Dr Bubb correctly points out that Wen et al1,2 found that the exercise-induced reductions in the risk of all-cause mortality continued to accrue with longer efforts. Yet, a 140% increase in one's time investment (from 50-120 min/d) would be expected to yield only an additional 5% risk reduction, from 40% to 45%.2 Furthermore, the definition of vigorous exercise is open to interpretation.3 Among the 416,000 Taiwanese adults in that study, those who did any activity at or above 6.5 metabolic equivalents (eg, jogging slowly, hiking, or doubles tennis, which most would not consider “vigorous exercise”) during a typical week were placed in the group of vigorous exercisers.
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