Target Heart Rate

Q: When I'm doing cardio, my target heart rate is supposed to be at 85 percent. How do I know what that is, and how do I measure it during my workout?

A: To determine your target heart rate, you should first figure out your maximum heart rate (MHR). This is done by subtracting your age from 220. For example, I'm 32, so check it out: 220 – 32 = 188 (so now I know my MHR is 188). Then I take 85 percent of 188, which gives me 160, so that's my target heart rate — the ideal number of times my heart should beat in one minute when I'm training.
The easiest way to keep track of your heart rate is by wearing a heart rate monitor. If you don't want to spring for one, no problem — just find your pulse, either on your wrist or on your neck (usually right next to your larynx), count the number of times your heart beats in 6 seconds, and then multiply that number by 10.
That said, it's pretty tough to keep your heart rate at 85 percent, so don't be discouraged if you can't at first. Work your way up to it. There will also be times when your heart rate will reach 100 percent of your MHR — if this happens, don't worry. It's not unhealthy, it's just VERY difficult to sustain over 45 to 60 minutes of cardio — which is why 85 percent is the magic number for cardio training.
One footnote before you start doing all the math: If you're on medication for a heart condition, talk to your doctor. Your healthy heart rate range might be a little different than you'd expect.