Calculation for heart rate in exercising women has been wrong

Important to know: the new formula eases exercise for women...  http://well.blogs.nytimes.com/2010/07/05/recalibrated-formula-eases-womens-workouts/?ref=health

EXCERPT:  The new study shows that for women, the number typically derived from the standard formula is far off the mark. Using the old formula of 220 minus age, a 40-year-old woman would achieve an average maximum heart rate of 180 beats per minute. That means her pulse should stay around 153 beats per minute during her workout to achieve a target heart rate of 85 percent.

But based on the new calculation, the same woman’s average maximum heart rate is 171 beats per minute, meaning her desired target heart rate is just 145 beats per minute, 8 beats a minute slower than under the old formula. Although the gap seems small on paper, it can be the difference between an exhilarating workout or a frustrating one that ends in exhaustion.