Re: The impact of excessive endurance exercise

First, thank you for a very important and well-written article [BCMJ 2016;58:203-209].I took a look at the four recent studies that were discussed in the “How much exercise is enough?” section and wonder if you can shed light on something. The clearest U-curve is found in the study on Copenhagen joggers.[1,2] The study on runners in Texas[3] also showed a U curve though it was less striking. The study on all forms of exercise in Taiwan,[4] however, showed a continued benefit with longer and more vigorous exercise.

The main differences in these studies that I found were:

  1. Difference in race: East Asian versus two white populations.
  2. Difference in exercise modality: running versus all forms.
  3. Difference in follow-up period: The study in Taiwan was only 8 years of follow-up, which is less than in Copenhagen or Texas, though the subgroup analysis in Copenhagen[2] was also around this length and showed a marked U-curve.

I didn’t see any obvious differences in other subject characteristics, though I may have missed something.

Are there any other studies suggesting differences in exercise benefits among different races or exercise modalities?

Thanks again for a stimulating article!
—Joel Fox, MD (PGY-1 Psychiatry)


1.    Schnohr P, Marott JL, Lange P, et al. Longevity in male and female joggers: The Copenhagen City Heart Study. Am J Epidemiol 2013;177:683-689.

2.    Schnohr P, O’Keefe JH, Marott JL, et al. Dose of jogging and long-term mortality: The Copenhagen City Heart Study. J Am Coll Cardiol 2015;65:411-419.

3.    Lee DC, Pate RR, Lavie CJ, et al. Leisure-time running reduces all-cause and cardiovascular mortality risk. J Am Coll Cardiol 2014;64:472-481.

4.    Wen CP, Wai JP, Tsai MK, et al. Minimum amount of physical activity for reduced mortality and extended life expectancy: A prospective cohort study. Lancet 2011;378(9798):1244-1253.

Joel Fox, MD (PGY-1 Psychiatry). Re: The impact of excessive endurance exercise. BCMJ, Vol. 58, No. 7, September, 2016, Page(s) 364 - Letters.

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