A heart-rate monitor can be a helpful tool in training. Tracking your heart rate with a monitor (which reads your pulse via a sensor built into a chest strap) tells you precisely how hard—or easy—your heart is working.
Measuring your heart rate can help you keep from making one of the most common mistakes that runners of all abilities make—running too fast too often, which puts you at risk for injury and burnout. But heart-rate training does have its limitations.
Here’s how to effectively use a heart-rate monitor in your exercise life.
Know your zones. When you work out using a heart-rate monitor, you’ll aim to work out within a specific zone. Hitting a “zone” means falling within a particular percentage of your heart rate during every workout—for example, 65 to 80 percent for most runs and 90 percent or more as you blaze to a fast race finish. For most of your workouts, your heart rate should fall into zone 1 or 2.
Here is a general guideline used by exercise physiologist and coach Janet Hamilton, owner of Atlanta-based Running Strong:
- Zone 1: 60 to 70 %; very comfortable effort; use this for warmup and cooldown
- Zone 2: 70 to 80 %; comfortable enough to hold a conversation; most training is done here
- Zone 3: 81 to 93%; “comfortably hard” effort; you may be able to say short, broken sentences.
- Zone 4: 94 to 100%; hard effort; the pace is sustainable, but conversation is a few words at a time. For most people this is around 5-K pace.
Know your numbers. For years, runners have been told to monitor their heart rate based on their maximum heart rate, using a formula of 220 minus your age. Now most experts agree that this formula may be inaccurate for most people. It’s better to monitor your heart rate based on something known as heart rate reserve, which is more accurate, says Hamilton.
Here’s how to find your heart-rate reserve:
- Get your max heart rate. You can get an estimate of your heart rate reserve, and your VO2 max, by doing any type of time trial or race at an all-out effort. In a 5-K race, you will likely be able to sustain about 97% of your max heart rate, Hamilton says. “5-K races are ideal,” says Hamilton. “The competitive environment brings out a greater effort in most people.” If you want to go all the way to 100%, do a two-mile time trial. Here’s how: On a track or any flat stretch of road, run one mile easy to warm up, then run two miles (eight laps around the track) at the fastest pace that you can sustain, trying to run each mile and each lap at roughly the same pace. Look at the heart-rate monitor, and see the maximum heart rate number that was hit. That is a good estimate of your max heart rate.
- Get your resting heart rate. Take your pulse at your neck or on your wrist as soon as you wake up, before you get out of bed. Find out how many beats per minute by counting your pulse for a full 60 seconds. Do this every day for one week.
- Find your heart rate reserve. Your heart rate reserve (HRR) is your max heart rate minus your resting heart rate.
- Know your zones. To find out which numbers to target on which runs, multiply your heart rate reserve by the zone you’re running in, then add back your resting heart rate.
Here’s an example:
- Let’s say you have a max heart rate of 190 and a resting heart rate of 60.
- Your heart rate reserve would be 190 – 60 = 130.
- To find out which number you should target for your warmup, when you want to be working at 65%, you’d use this formula:
- Heart Rate Reserve x 65% + Resting heart rate
- 130 x 0.65 (65% of heart rate for an easy run) = 84.5 + 60 (Resting heart rate) = 144.5
- So you’d target about 144 for your warmup. If the number is higher, you’re working too hard. If it’s lower, you need to pick up the pace.
See an expert. If you’re really curious about finding out precisely what your max heart rate and heart rate reserve are, go to an exercise physiologist and do a treadmill test. This test typically involves running on a treadmill while hooked up to machines that monitor your heart rate and blood pressure, as well as how much oxygen you’re consuming. Every few minutes the treadmill gets faster and steeper, until you reach the maximum effort you can sustain. Your heart rate at that maximum effort is your max heart rate.
Know the limits. Even when you know your max heart rate, and know the training zones, realize that there are limitations when using a heart-rate monitor to gauge how hard you’re working out. If you’re wearing your heart-rate monitor in a gym, the signals from the machines might interfere with an accurate reading. Also, certain other factors that have little to do with your level of fitness will impact your heart rate. If you’re dehydrated, if it’s a superhot day, or if you’re in pain, your heart rate might skyrocket, even if you’re running at a slower pace. Certain medications, such as beta-blockers and some migraine medicines, will affect the numbers you see on your heart-rate monitor. Similarly, if you’re going up a hill, you may have to slow your pace just to maintain the same intensity. In some cases you may have to walk. That’s okay. As you get fitter, you’ll be able to run up them.
Decide if heart-rate monitoring is right for you. When you’re just starting to work out, you have to carefully weigh whether this is right to you. It’s best to work by feel at first. Spend time getting into a rhythm of walking or running that feels comfortable enough to hold a conversation. It takes a while to get to a point where the running feels relaxed and natural. Once you do, you should target that feeling during each run. Studies have shown that running by feel and doing the talk test, which is well correlated with target paces. All you need is a watch. If you’re doing a run/walk workout, be aware that there will be a natural lag between when you hit a certain pace or heart-rate zone and when that number registers on the heart-rate monitor, says Hamilton. So if you’re doing a run/walk interval by time, there’s a good chance that you may have returned to a walk before seeing your target heart rate for the run register on the heart-rate monitor. On the other hand, having a heart-rate monitor will keep you from going out too fast and burning out before you’ve reached the goal distance and duration of the workout. Staying in your ideal zone of 60 to 80 percent will help you practice running in that relaxed, comfortable pace that you want to hit for most of your runs, Hamilton adds.
Before you invest in a heart-rate monitor, it’s best to talk with your doctor, a pharmacist, or an exercise physiologist to discuss any and all medications and supplements you’re taking and what individual impact those may have on your readings.