In the study of 3,300 Norwegian adults, this standard formula was shown to underestimate top heart rate values in 77% of the cases. In fact, the formula churned out too-low results for up to 90% of those between the ages of 40 and 60, and in 60 to 69-year-olds, the inaccuracy translated to an average under-prediction of 15 beats per minute below the rate they could actually reach. What’s the big deal? Knowing the true value of your maximum heart rate is key for getting your best workout. The CDC recommends that you reach 70 to 85% of your maximum heart rate during vigorous physical activity. If you, your cardio machine, and workout instructors are basing those targets on a too-low estimate, you’re not going to get the results you want. To get an on-point estimate of your maximum heart rate, you’ll need a heart rate monitor with a transmitter belt that runs across your chest (Prevention fitness advisor Wayne Wescott, PhD, recommends the Timex Ironman Road Digital Heart Rate Monitor), and wear it while performing this simple test with the aerobic activity of your choice: 1. Warm up for 5 to 10 minutes. 2. Increase your exercise intensity quickly until your reach the highest heart rate you think you can sustain for 4 minutes. 3. Once the 4 minutes are up, go at a recovery pace for 2 more. 4. Ramp up to your highest sustainable heart rate for one more intense 4-minute interval. 5. Cool down and average your two 4-minute heart rate numbers to get your max heart rate estimate. More from Prevention: How To Lose The Last 10 Pounds
