More on Heart Rate

OK, so this heart rate training might be for you. But how do you know if and when you’re in that magical 60 percent to 70 percent of maximal heart rate that gives aerobic benefits without increased risk of burnout and injury? Here’s where heart rate training can get tricky, especially if you don’t like the whole idea of quantifying something that can be as free-flowing as running.

If you’re going to train between 60 percent and 70 percent of your maximal heart rate, then you need to know what that top figure is. You’ve probably seen this or that formula for determining your maximal heart rate. The most famous one is 220 minus your age. Say you’re 40 years old. This formula would say that your maximal heart rate is 180 (220–40). Using this number, you should run fast enough to get your heart rate up to between 108 (60 percent of 180) and 126 (70 percent). Sounds simple even for an idiot, right?

Unfortunately, any formula that you use to calculate your maximal heart rate is going to be inaccurate. The formulas are based on the average maximal heart rates for a person of a given age. So an average 40-year-old has a maximal heart rate of 180. Trouble is, your maximal heart rate may be as much as 20 beats above or below this average. Remember that maximal heart rate is something you’re born with; it isn’t a reflection of your fitness. If you have that base level of fitness and want to find your maximal heart rate, here’s how. If you run a 5K race and can honestly say that by the end you were working as hard as you can, then your heart rate at the finish is probably within a few beats of your maximal heart rate. Or try this test: Warm up with some very easy running for 10 minutes or so. Do a few accelerations of 15 to 20 seconds at a pretty fast pace. Catch your breath, and then run as hard as you can for two minutes. Pace yourself so that you maintain about the same speed throughout. If you run as hard as you can, you’ll most likely be within two to three beats of your maximal heart rate by the end of the run. If you aren’t sure whether you gave an all-out effort, jog for 10 minutes and repeat the test. Some runners find that they get a slightly higher heart rate if they perform this test uphill.

You can do these tests without wearing a heart rate monitor if you take your pulse for six seconds almost immediately upon finishing. But if you wait too long or take your pulse for too long, your heart rate is going to start to fall. So take your pulse for six seconds, and then multiply that number by 10 to get a decent estimate of your maximal heart rate. For example, if at the end of a 5K, your heart beats 17 times in six seconds almost immediately after you’ve stopped, then call your maximal heart rate 170. Once you’ve determined your maximal heart rate, the rest is easy. Multiply your maximal heart rate by 60 percent and by 70 percent, memorize those numbers, and be sure that you stay within that range on your normal distance runs.