Chances are pretty good that if you regularly read this magazine, you already know a thing or two about your own heart rate; after all, you make a concerted effort to raise it several times a week to improve or maintain your body composition. You may also know one or more ways to find your heart rate. The most common is to lightly place your index and middle fingers on the palm side of your opposite wrist until you feel a pulse. Keeping your eyes on a clock for six seconds, count the number of beats and then add a zero to the end to find your beats per minute (bpm). You may even know the mathematical formula to determine your maximum heart rate (220 minus your age) and be able to calculate your target training intensity (220 minus your age, multiplied by the percentage you’re aiming for). Let’s say you’re a 38-year-old athlete who has a maximum heart rate (MHR) of 182 (220 – 38). To train between 65 and 75 percent of your MHR, you’d try to keep your bpm between 118 and 137 (220 minus 38 multiplied by 0.65 and 0.75, respectively).
Those are the basics, and at best they’ll give you a ballpark figure that you can try to meet in the gym. But if you get to know just a little bit more about your own heart rate, you can pinpoint your target heart rates more accurately and reach your goals more quickly.
To do that, you need to find your heart-rate reserve (HRR), which is simply the difference between your MHR and resting heart rate (RHR). To calculate your RHR, take your pulse for one minute right after waking up in the morning, before you get out of bed. (If you have a severely annoying alarm clock, turn it off and lie quietly for five minutes before taking your pulse, as alarms tend to elevate heart rate.) Do this five mornings in a row, then calculate the average. The result is your RHR, and the better your cardiovascular fitness, the lower that number will be. Then you can use it in what’s called the Karvonen formula:
(HRR x training percentage) + RHR = THR.
Say you find that you have an RHR of 55 and you still want to train between 65 and 75 percent of your MHR. You would first find your heart-rate reserve by subtracting your RHR from your MHR (182 – 55) and get 127. To find your target heart-rate range, you’d do the following calculations:
(127 x 0.65) + 55 = 138 bpm
(127 x 0.75) + 55 = 150 bpm
Notice the results here are significantly higher than the more widely used formula mentioned earlier. By taking RHR into account, you’ve just discovered that you can push yourself harder than you thought, translating into better cardiovascular and physique results in less time.
Yes, that’s a lot of math, and it can be pretty difficult to take your distal pulse in your wrist while jogging on a treadmill, which is why virtually every piece of cardio equipment you find in a commercial gym comes equipped with a heart-rate monitor. But don’t trust it, says Jim Ryno, a celebrity trainer and founder of LIFT, a chain of private personal-training gyms in New Jersey and New York City.
“They test them on bigger guys who are in shape, so the numbers are always going to be inflated,” he says. Even when you program your weight into the machine, “there’s no way it can take into account your actual intensity,” Ryno explains.
Better to invest in a wireless heart-rate monitor such as those by Fitbit, Garmin or Polar that you can program with your real information, and leave the sweaty handgrips to the next big guy who comes along.
BPM: beats per minute
MHR: maximum heart rate
THR: target heart rate
RHR: resting heart rate
HRR: heart-rate reserve