2,344 participants finished the 12-km Eremitagelobet, the first large-scale jogging race in Denmark and one of the first in the world, during which a naval officer died at 46 years of age. In the following years, several reports of death during jogging were published. As a result, some physicians came to believe that jogging could be dangerous, even at a slow pace. In fact, slow jogging (at 8 km/hour, expending 600 kcal/hour) is considered a vigorous activity (with a metabolic equivalent task

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... ore of ≥6). Therefore, to study whether jogging could be harmful to health, we included questions about jogging in the first Copenhagen City Heart Study examination in 1976-1978. We have previously investigated total leisure-time physical activity and the risk of death in 7,023 healthy individuals and found that both men and women who regularly engage in low levels of physical activity for less than 2 hours per week have a significantly higher risk of death than individuals who engage in 2-4 hours per week of leisure-time physical activity. Yet, no further risk reduction occurred when physical activity was increased to more than 4 hours per week (3), which does not support a linear relationship between the amount of weekly exercise and mortality. This could be caused by the inclusion of a much wider age span in our study (20-98 years) compared with that in the study by Manini et al. (4). In our study, we found that the 1,878 joggers had significantly lower mortality than nonjoggers, with an age-adjusted hazard ratio of death of 0.56 (95% confidence interval: 0.46,