If you’re a woman who has melted her toenail polish and nearly collapsed from exhaustion struggling to push your pulse into a target heart rate that will boost your cardiovascular fitness, I have news for you: Cool it! Slow down. Stop pushing so hard. The old formula for figuring out your maximum heart rate, and from there your fitness zone, has been recalibrated by exercise researchers at Northwestern University. The new formula is as welcome as a second wind.
Before I pass along the new and improved formula, let’s review the old one you see posted in gyms and on treadmills across America, the one that’s been considered the Gold Standard for the past 40 years. It’s imprecise, and some say it’s flat-out wrong, but it lives on because it caught on many years ago and all the people who have invested in heart rate monitors want to believe it’s true.
To find your ideal exercising heart rate, the common wisdom goes, you start at 220 and subtract your age. The resulting number is your maximum heart rate – MHR. Your target training zone is then calculated at 65 percent to 85 percent of the MHR, depending on whether you want to burn fat, build aerobic capacity or boost your endurance. A 40-year-old woman runner who wants to work at 85 percent of her maximum, for instance, would start at 220, subtract 40 and run hard enough and long enough to push her pulse to about 153 beats per minute (and keep it there for 20 minutes to 30 minutes).
It’s a very tough thing to do, and now we know why. The old fitness formula doesn’t work for most women because it was based on research done exclusively with men. Dr. Martha Gulati, a cardiologist at Northwestern’s Center for Women’s Cardiovascular Health, and her treadmill-testing team of researchers have studied nearly 5,500 healthy females, ages 35 to 93, for 16 years. Their recalculated formula for computing MHR is 206 minus 88 percent of a woman’s age. In the example of our 40-year-old runner who wants to work out at 85 percent of her maximum, the new maximum is 171 beats per minute, and her new target heart rate is 145 beats per minute, or eight beats a minute slower than the old formula.
Those eight beats may not sound like a lot to you, but for an athletic female who runs, bikes or swims for fitness, it’s a major downshift that will lead to workouts that are saner, safer and less exhausting.
And that leads us to the take-home lesson for today, as true for men as it is for women: For elite, competitive athletes, fitness is a strict numbers game, a measure of how much oxygen you consume during a given activity.
But for most of us who are interested in living a healthier, happier lifestyle, keeping track of your heart rate isn’t as important as finding physical activities you enjoy and are willing to do – with regularity, pleasure and enthusiasm – for the rest of your life.
Grunting and groaning through your workout just so you can reach your target zone is not a smart way to work on your fitness, no matter what formula you use. If you’re suffering that much, your body is going to find a reason to quit. You’ll get bored, or you’ll get injured. The trick is to make fitness fun, something you enjoy, not just endure.
Is it useful to wear a heart rate monitor when you work out? That depends on you. If you’re inspired and motivated by all that digital feedback, then by all means, wear a heart rate monitor and have your best time. Just don’t push yourself so hard that you feel breathless or exhausted. A good heart rate monitor will actually slow down some hard-driving type-A people who would otherwise push themselves too far, and that’s another very good reason to own one.
But some people don’t like to tie their workouts to technology. Heart rate monitors make them anxious, and that’s OK, too. These people find their own pace and learn to step it up as need be, using sprints, intervals and uphills to challenge their heart and lungs – but not to the point of extreme discomfort.
No pain, no gain is no way to calculate your fitness.