Too much exercise can be dangerous for patients with heart problems

A new research has found that too much exercise may increase the risk of death from heart attack or stroke in patients with existing heart problems.

The new study tracked a decade's worth of exercise habits and survival of more than 1,000 people with diagnosed-but stable-coronary artery disease.

The majority of the study's participants were in their 60s and had attended a cardiac rehabilitation program to avoid future heart attacks or strokes.

Around 40 percent of the study participants did an hour of moderate-intensity aerobic activity 2 to 4 times per week; of the remaining 60 percent, half exercised at that level more than four times a week and the other half exercised less. Overall, 1 in 10 said they rarely or never exercised.

The researchers found those who were most sedentary were around twice as likely to have a heart attack or stroke as those who were regularly physically active, CBS News reported.

They were around four times as likely to die of cardiovascular events and all other causes.

But more surprisingly, those who did the most strenuous daily exercise were also more likely to die of a heart attack or stroke than people who engaged in more moderate activity.

The study is published in the journal Heart.