Exercise may be the best way to keep hearts healthy -- and it works even for people with a genetic pre-disposition for heart disease, according to new findings in the American Heart Association's journal, Circulation.

Data assessed from roughly a half-million people in the UK Biobank database showed that greater grip strength, more physical activity and better cardiorespiratory fitness are all associated with reduced risk for heart attacks and stroke, even among people with a genetic predisposition for heart disease.

For participants with an intermediate genetic risk for cardiovascular diseases, those with the strongest grips were 36 percent less likely to develop coronary heart disease and had a 46 percent reduction in their risk for atrial fibrillation compared to study participants with the same genetic risk who had the weakest grips.

Among individuals deemed at high genetic risk for cardiovascular diseases, high levels of cardiorespiratory fitness were associated with a 49 percent lower risk for coronary heart disease and a 60 percent lower risk for atrial fibrillation compared to study participants with low cardiorespiratory fitness.

"The main message of this study is that being physically active is associated with a lower risk of heart disease, even if you have a high genetic risk," said Erik Ingelsson, M.D., Ph.D., lead author of the study and a professor of Medicine at Stanford University School of Medicine in California.

There are a few caveats: the study is not a prescription for a specific type or amount of exercise and because the results come from an observational study, Ingelsson said, "we can't definitely claim a causal connection." Observational studies are designed to establish trends.

Nonetheless, he said the data is robust and these latest results are worthy for consideration in guidelines. For individuals, "it would be best to discuss a physical activity plan with a physician," Ingelsson said.

Participants in the UK Biobank Study are from England, Scotland and Wales and gave their consent to have their genetic pre-disposition for diseases assessed when the study began. At the start of the study, they had no evidence of heart disease. Data from 482,702 participants, aged 40-69, was included in the published analysis. More than half of the participants were women.

The International Physical Activity Questionnaire was used to assess self-reported exercise, while wrist-worn accelerometers, hand dynamometers (grip strength) and submaximal exercise treadmill were used for objective measures. Additionally, 468,095 individuals had genome-wide genetic data.

The results were adjusted for age, gender, ethnicity, region, socioeconomic status, diabetes, smoking, systolic blood pressure, body mass index and use of lipid medications.

Previous research found associations between exercise and heart health, but Ingelsson said that less was known about the cardiovascular effect of exercise in persons with a family history of heart disease. This analysis was designed to answer two questions: is physical activity and fitness associated with lower risk of cardiovascular events and what effect -- if any -- does genetic predisposition play in that equation.

During follow-up, there were 20,914 reported cardiovascular events, which included heart attacks, strokes, atrial fibrillation and heart failure.