Relationship Between Heart Rate and Cardiovascular Fitness

If you're working on your cardio fitness, heart rate tracking is an effective way of gauging both your workout intensity and how your fitness improves.

There are three types of heart rate that might be used to gauge your fitness level or monitor your level of exertion.

The first is your resting heart rate — literally, the number of times your heart beats per minute when you're at rest. As the UK National Health Service points out, you need to rest quietly for at least five minutes before taking your resting heart rate — although some professionals might ask you to take your resting heart rate right after you wake up in the morning, before you get out of bed.

In general, a lower resting heart rate correlates with good health. The American Heart Association notes that if you are calm, relaxed, not ill and are sitting or lying down, your resting heart rate is typically between 60 beats per minute and 100 bpm.

Having a too-low resting heart rate can signal medical problems, but it can also be the result of medications such as beta blockers; very athletic or active people may have a resting heart rate that's as low as 40, simply because their heart — which is a muscle, after all — is more fit and doesn't have to work as hard to keep blood circulating through the body.

The second is your heart rate as you're exercising. For many people, this is an excellent way of monitoring exercise intensity; the more vigorously you exercise, the higher your heart rate will be.

The third type of heart rate you might take, although it's the least common for "civilians" in the exercise world, is your recovery heart rate. This entails taking your heart rate after exercise, at a proscribed time interval following the cessation of activity. As noted at Berkeley Wellness, your recovery heart rate is a good way of gauging fitness; the fitter you are, the more quickly it returns to a normal state. Resting heart rate is most commonly used as part of an exercise stress test or as part of submaximal fitness testing done with a trainer.

You generally don't need to worry about checking your recovery heart rate, although tracking its changes over time can give you a sense of how your fitness has changed. If you do want to use this sort of measurement, talk to your doctor about appropriate standards for your age, or consult a standardized fitness test protocol like the YMCA Bench Step Test.

Read more: 10 Simple Ways to Improve Your Heart Health

Barring a clinical setting, the simplest and most accurate standard for measuring your heart rate while exercising is to locate the pulse point at your neck or wrist, then count the heartbeats until a timer tells you that 60 seconds have elapsed. You can also count for a shorter period and multiply the result to get the number of beats in 60 seconds — for example, count for 10 seconds, then multiply by 6 — but this result is less accurate.

However, there are a couple of obvious problems with that method. First, it can affect your exercise intensity, which in turn affects the accuracy of your heart rate reading. If you don't believe that, try taking an accurate heart rate while swimming laps or using the moving handlebars on an elliptical trainer. The second issue is that if you stop to take your heart rate, your heartbeat immediately starts to drop (gradually) back down to a state of rest — which again skews your results.

Still, if you want help gauging your workout intensity, taking your heart rate is an easy, useful and — best of all — free way to get started. You can also gauge your level of exertion using the "talk test" or the rating of perceived exertion scale, or pair either of those with heart rate monitoring.

If you find that taking your heart rate suits you, consider investing in some equipment to help you get more accurate readings without having to pause. As Harvard Health Publishing notes, the hand-grip heart monitors built into exercise equipment are notoriously inaccurate, and heart rate results from fitness trackers can be variable at best. The most accurate results will come from using a chest-strap heart rate monitor, which transmits the results to a wrist watch or smartphone readout.

Read more: 8 High-Tech Gadgets to Keep Your Heart Healthy

What sort of heart rate should you have while you exercise? If you're under a doctor's care for any cardiovascular condition or are taking medication that can affect your heart rate, that's a loaded question. In such cases, consult your medical team to find out if you should be using different norms than the general public.

However, barring any of those extenuating circumstances, the American Heart Association offers a target heart rate chart that estimates your maximum heart rate and your target heart rate zone according to your age. Note that your goal shouldn't be to reach your maximum heart rate; instead, stick to the lower half of your target heart rate zone for low to moderate exercise intensity, or aim for the higher half of the target heart zone for a moderate to vigorous or strenuous exercise intensity.

Depending on your vintage, you might have heard those or similar ranges described as the "fat-burning zone" for moderate intensity workouts, and the "cardio zone" for more intense workouts. However, rest assured that any sort of aerobic exercise is good for burning calories and strengthening your heart, as long as you're not overdoing the intensity relative to your fitness level.

The AHA's target heart rates are based on a relatively simple and time-tested formula. If you'd like a more specific estimate of your target heart rates, considering using one of the other formulas described by the American Council on Exercise.