If you’ve been wondering whether your exercise routine is doing anything for the health of your heart, a new study offers proof practically beyond a shadow of a doubt. Earlier studies had shown the incredible effect that exercising vigorously has on heart health, but this is the first to show that even moderate, routine activities – like mopping or taking an hour-long walk – can also improve heart health considerably.

The team found that people who exercised even moderately had a 50% increase in blood vessel dilation, compared to inactive people, a dramatic difference.

As study author Michael McConnell said in the Stanford University news release, "My patients ask me, ‘How do we really know that exercise is benefiting my heart arteries?’ Now we can say that we’ve looked directly at their arteries and shown that the more physically active subjects, even in their 60s, see measurable benefits."

The McConnell and his team first had 212 people between the ages of 60 and 72 answer questions about their daily activity. Moderate activity included walking briskly or mopping; intense activity might be doubles tennis or doing construction work; and very intense activity included activities like running or chopping wood.

The participants were given a dose nitroglycerin, which gets converted to nitric oxide in the body. Nitric oxide is the compound that causes the blood vessels dilate, so the researchers were able to challenge blood vessel function using this simple technique. They observed the degree to which blood vessels dilated using a sophisticated MRI technique, before and after the patients were given the nitroglycerin.

The team found that people who exercised even moderately had a 50% increase in blood vessel dilation, compared to inactive people, a dramatic difference.

"If you exercise more, your vessels dilate more," explains McConnell. "The more a vessel dilates, the healthier the vessel. Those who don’t do anything beyond light activity have by far the lowest dilation levels. Those who include high-level activities, like singles tennis or swimming, at least once a week dilated their heart arteries twice as much."

Most Americans don’t get enough exercise, according to the American Heart Association (AHA). They also state that for every hour one walks, one’s life expectancy can increase by two hours. What’s more, study after study has shown that being sedentary – sitting for long hours – can take a dramatic toll on our heart health and longevity. Even walking 30 minutes a day can have a power effect on the health of your heart, according to the AHA, so get moving!

The study was published in the June 13, 2011 online edition of Journal of the American College of Cardiology: Cardiovascular Imaging.