From WebMD: April 6, 2010 — Women who walk two or more hours per week or who walk at a brisk pace can significantly reduce their risk of suffering a stroke, new research indicates. “The findings are based on a study of the exercising habits of 39,315 female health professionals whose average age was 54. It found that: Women who walked at a pace of 3 miles per hour or faster had a 37% lower risk of suffering any type of stroke. Women who walked two or more hours a week had a 30% reduced risk of any type of stroke. . . Stroke is the third leading cause of death and the leading cause of adult disability in the U.S., so it’s important to identify ways to prevent them. Other risk factors for women include smoking, obesity, migraine headaches, postmenopausal hormone use, and taking oral contraceptives.” Maybe women who can brisk-walk can move fast because they eat well and easily breathe because they do not smoke. Measure how fast you walk:

Calories burned per mile do not vary much at different walking speeds, so you do not need to be exact.

*Easy Health Walk: If you take an easy walk around the neighborhood or park, able to keep up a full conversation, use 3 miles per hour or 5 kilometers per hour as a rule of thumb.
*Moderate to Brisk Walk: If you are walking at a determined to swift pace and breathing noticeably, use 4 miles per hour or 6.5 kilometers per hour.
*Fast Walking: Fast walkers usually know their speed or have measured it. Racewalkers can walk 5-6 miles per hour or even faster. That is 8-10 kilometers per hour.
How to Measure Your Speed with the Google Map Pedometer

You can measure your walking speed by using a watch and any convenient route using the Google Map Pedometer. You can start from any US address or you can zoom in and out until you find your location. Then click to draw the route on the map to find out an accurate distance. Input your time and weight and it will tell you your speed, pace, and calories burned.