We appreciate the comments by Messerli et al and the information about an inverse relationship between physical activity and certain cardiovascular risk factors. However, they suggest a possible undefined upper limit of the dose response curve between physical activity and most cardiovascular risk factors. However, we observed, when stratifying by age, a U-shaped relationship between sustained physical activity and systolic blood pressure for certain age groups. This pattern was especially evident among men 40 to 49 years old at study entry after 7 years of increasing levels of leisure time activity (Table 1). This finding indicates a higher level of physical activity effect on systolic blood pressure. Among women, the high and very high activity level were merged (few women reported a very high activity level), and the U-shaped relationship was less marked. This U-shaped relationship was not observed after 7 years among those 30 to 39 years old at entry; for this age group our results corroborate with other studies of the same age group.1 In contrast, this age-related U-shaped relationship was not observed between physical activity and diastolic blood pressure for either sex in our study.
Thune I, Njølstad I, Løchen ML. Cardiovascular Risk Factors and Physical Activity: How Much Is Enough?. Arch Intern Med. 1999;159(8):882-883. doi: