12th August 2014 – A new US study has found an increased risk of cardiovascular deaths in heart attack survivors who exercise by running and walking to excess.
It means, contrary to popular belief, more exercise may not always be better.
Paul Williams of the Life Sciences Division, in Berkeley California and Dr Paul Thompson, of the Department of Cardiology, Hartford Hospital, in Connecticut, studied the relationship between exercise and cardiovascular disease-related deaths in 2,377 physically active heart attack survivors, both men and women.
Their research has been published in the scientific journal, Mayo Clinic Proceedings, and found what they say is 'clear evidence' of an increase in cardiovascular deaths in heart attack survivors who exercised to excess.
There is strong evidence of the importance of regular physical activity, such as brisk walking and jogging, in the management and rehabilitation of cardiovascular disease and in lowering the risk of death from other diseases such as high blood pressure and stroke.
The new study confirmed that physically inactive individuals were at the highest risk of harmful outcomes. An accompanying editorial says the most sedentary group had a 2-fold increased risk of heart attack or stroke and 4-fold increased risk of death compared with the moderately active group.
The researchers found reductions in deaths from cardiovascular events of up to 65% among patients who were running up to 30 miles or walking up to than 46 miles per week. Beyond this point however, the authors say much of the benefit of exercise was lost. Furthermore, people who performed such strenuous exercise on a daily basis were about twice as likely to die of heart attack or stroke compared with the moderately active individuals.
"These analyses provide what is to our knowledge the first data in humans demonstrating a statistically significant increase in cardiovascular risk with the highest levels of exercise," say the authors in a prepared comment. "Results suggest that the benefits of running or walking do not accrue indefinitely and that above some level, perhaps 30 miles per week of running, there is a significant increase in risk. Competitive running events also appear to increase the risk of an acute event."
Dr Carl Lavie, who is a cardiologist at the John Ochsner Heart and Vascular Institute, in New Orleans, says in a press release: "For patients with heart disease, almost all should be exercising, and generally most should be exercising 30-40 minutes most days, but from a health stand-point, there is no reason to exercise much longer than that and especially not more than 60 minutes on most days."
Reacting to the study in a statement, Amy Thompson, senior cardiac nurse at the British Heart Foundation says: "We shouldn’t be alarmed just yet, the study failed to include people free of heart disease and further research is needed before we can draw any firm conclusions. In the mean time we should all try and build exercise into our daily routines to keep our hearts healthy.
"If you are concerned about exercising with a heart condition, visit your GP for advice."
Mayo Clinic Proceedings: Increased Cardiovascular Disease Mortality Associated With Excessive Exercise in Heart Attack Survivors. Paul T. Williams, PhD, and Paul D. Thompson, MD
Editorial: Exercising for Health and Longevity vs Peak Performance: Different Regimens for Different Goals
Elsevier press release
British Heart Foundation
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