By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) – I talk about it all the time. One of my favorite recommendations is moderate exercise. But what is considered moderate exercise?

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Take, for example, walking. How much walking is moderate exercise?

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People should be walking 3,000 steps in 30 minutes to get meaningful exercise from walking.

Interesting research was done at San Diego State University. Researchers studied men and women walking on treadmills and they determined the rate of walking that would change heart rates enough to reach the level of moderate exercise. Moderate exercise has been linked to better physical health.

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Researchers say people need 30 minutes 5 times a week to do the best. We are talking about one hundred steps per minute.