This article is more than 5 years old. Information may no longer be current.
Excessive exercise increased CVD mortality risk among MI survivors
Click Here to Manage Email Alerts
Running or walking progressively decreased risk for CVD-related mortality among survivors of prior MI up to a certain point, but excessive exercise significantly increased CVD mortality risk in a recent prospective study published in Mayo Clinic Proceedings.
Participants who reported running more than 7.1 km/day or walking briskly for more than 10.7 km/day were more likely to die of CVD-related causes, particularly ischemic heart disease, the researchers wrote.
They evaluated data collected from 2,377 self-identified survivors of prior MI, as indicated by responses to baseline surveys for the National Runners’ Health Study (n=678 males and 126 females) or the National Walkers’ Health Study (n=942 males and 631 females). Estimated energy expenditure, defined as metabolic equivalent of the task, per hour, per day (MET-h/d), for both walking and running was calculated for each participant. Incidence of mortality within the cohort was assessed between 1991 and 2008 (mean 10.4 years), with all CVD-related mortality as the primary endpoint.
During follow-up, 526 patients died, including 376 due to CVD-related issues. The deaths included 290 male and 125 female walkers and 102 male and nine female runners.
Compared with patients reporting the least amount of exercise (<1.07 MET-h/d), risk for CVD-related mortality was decreased by 21% among those with 1.07 MET-h/d to 1.8 MET-h/d of walking or running (P=.11), 24% among those with 1.8 MET-h/d to 3.6 MET-h/d (P=.04), 50% among those with 3.6 MET-h/d to 5.4 MET-h/d (P=.001) and 63% among those with 5.4 MET-h/d to 7.2 MET-h/d (P<.001). However, those reporting 7.2 MET-h/d or greater had a similar mortality risk compared with the lowest exercise group (P=.68).
On average, the researchers wrote, patients had a 15% reduction in CVD mortality risk per 1 MET-h/d up until 7.2 MET-h/d (HR=0.85; 95% CI, 0.79-0.91), above which point the risk increased significantly (HR=2.62; 95% CI, 1.29-5.06). Specifically, risk among those with >7.2 MET-h/d was increased by 3.2 times for all mortality related to ischemic heart disease (HR=3.19; 95% CI, 1.42-6.79), but not for all-cause mortality or death related to arrhythmia or CVD other than ischemic heart disease.
The observed associations were not significantly affected by sex, years of exercise, age upon prior MI or the number of years since MI. Analysis according to walkers and runners separately also yielded similar results.
“These analyses provide what is, to our knowledge, the first data in humans demonstrating a statistically significant increase in CV risk with the highest levels of exercise,” the researchers concluded. “Moreover, we demonstrated the increased risk prospectively. These data were obtained in heart attack survivors, and require confirmation in cohorts of healthy subjects before concerns about excessive exercise can be extended to the general public.”
Disclosure: The study was supported by a grant from the NHLBI.
Click Here to Manage Email Alerts