Target Heart Rate: Does it really matter?

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What is Target Heart Rate?

Your target heart rate is a range of numbers that reflect how fast your heart should be beating when you exercise. During exercise, you can monitor heart rate and try to reach this target zone. Doctors also use target heart rate to interpret the results of a cardiac stress test.

Why should you be looking at your Target Heart Rate?

The importance of heart rate comes into play when you’re looking to achieve a fitness goal. You may want to run a marathon next year or lose a few pounds. Use your heart rate to know if your exercises are effective enough for these lofty goals.

Your resting heart rate as an adult can range from 60 to 100 BPM or beats per minute. Therefore, your exercises must get your rate higher than this range. Walking at a slow pace, for example, may not give you the exercise that you need. You’re in the area of under-training, which doesn’t lead to either a better fitness level or lost weight.

Does your Heart Rate influence your body’s Fat-Burning ability?

It doesn’t influence your body’s fat burning ability, but it does give you a reference for how much fat you’re actually burning. Fat is burned during every exercise session, so the more you work out, the more you’ll see cardiovascular improvements. The amount of fat burned is determined by your intensity level and duration.

When working out in lower intensity zones (50-60% HRMax), 85% of the calories burned are fat but overall you’re burning fewer calories than if you exercised at higher intensity. The good news is that this is the zone that’s sustainable for the longest amount of time.

When you reach 60-70% HRMax, roughly 65% of the calories you burn are fat.

Finally, working at 70-80% HRMax about 45% of the calories burned are fat. But your burning a higher number of overall calories compared to other heart rate zones.

Why do you burn less fat the harder you work out? Once your heart rate increases, you’re not taking in as much oxygen. You can’t oxidize fat fast enough. Your body turns to another, more readily available energy source to provide fuel for you — glycogen, also known as carbohydrates.

What are the Heart Rate Zones?

We all have a personal resting heart rate, ‘a minimum heart rate’, and a maximum heart rate. And between these values are different HR zones that correspond to training intensity and training benefit.

Heart rate zones are a percentage of your maximum heart rate (heartbeats per minute). Exercise too close to your maximum HR (Mhr) and your heart and body will struggle to keep up with the demands. The goal of heart rate zones is to make you the most efficient, but to allow you to challenge yourself to improve cardiovascular fitness.

Heart rate zones let you know how hard your heart is working and what energy source you’re using — carbohydrates or fat. The higher your heart rate gets, the more you’re relying on glycogen from carbohydrates for fuel.

For endurance athletes, it’s best to exercise in the zones that mostly rely on fat for fuel. Fat is a longer-lasting energy source and better for longer, intense workouts.

The Five Heart Rate Zones

Zone 1: Very Light Intensity (50-60% HRMax)

This low-intensity heart rate zone range is a very light effort, in which you can easily control your heart rate (such as walking or leisurely cycling at a steady pace). You'll stay in this zone for active recovery days so you're ready to train at a higher level during your next workout. Other potential activities in this zone might include Pilates, stretching, or another light movement.

Zone 2: Light Intensity (60-70% HRMax)

If you want to train yourself to run longer, get comfy at this moderate to moderately hard intensity. In this heart rate zone, you'll improve your muscular fitness, decrease your insulin resistance, and increase your body's ability to transport oxygen to your muscles. In this zone, you should be able to train for longer periods of time (think: 30 to 60 minutes) doing low intensity steady state activities such as rowing, using the elliptical, swimming, biking, or jogging without feeling totally gassed.

Zone 3: Moderate Intensity (70-80% HRMax)

Exercising in this vigorous-intensity range trains you to go harder for longer, and can help increase your speed and power. By increasing your time spent in zone 3, you're able to complete workouts in zone 2 with less effort. One prime example of training in zone 3: tempo running, in which you run at an uncomfortable pace (but not an all-out sprint) for several minutes at a time.

Zone 4: Hard Intensity (80-90% HRMax)

You'll hit zone 4 in high-intensity interval training (HIIT) workouts, in which you'll alternate between bursts of heart-pumping, tough exercise and active recovery or total rest. Heart rate training in zone 4 with HIIT workouts comes with a ton of benefits, too — such as improved cardiovascular health, VO2 max, and excess post-exercise oxygen consumption (aka your body keeps burning calories long after your workout).

Zone 5: Maximum Intensity (90-100% HRMax)

Zone 5 is an all-out, max effort that will likely have you gasping for breath. You'll be unable to maintain a heart rate training zone 5 effort level for more than a minute, tops — but by sprinkling zone 5 efforts into your workouts, you'll improve your stamina (the amount of time you can work at your maximum output) and build strength. Some zone 5 workout moves might be pushing a sled as fast as possible, a Tabata set of battle rope slams, or hitting your one-rep max in squats.

How to calculate your Heart Rate Training Zones

There are a couple of ways to calculate your heart rate zones, whether or not you have a heart rate monitor or fitness tracker. Begin by calculating your max heart rate — aka the highest number of beats your heart can pump per minute when it's under high stress. The most common formulas to calculate max heart rate, per Raffle, are:

220 − your age [or]
207 − (your age × .7)

The latter formula is newer and thought to be more accurate. For example, using these formulas, the max heart rate of a 30-year-old would be 190 or 186, respectively.

From there, you'll use your max heart rate to calculate your heart rate training zones.

To keep accurate tracking consider investing in the WHOOP (a tracker design for elite athletes and performance tracking), an endurance activity/running watch such as a Garmin, a FitBit for more general activity and step tracking, or an Apple Watch for a tech device that fits seamlessly into your everyday life.

The Truth Is…

Despite a lot of good information out there about heart rate training zones, there are also some misconceptions about the idea.

The growing popularity of heart rate monitoring among fitness enthusiasts has caused a bit too much focus on the heart rate, with many people assuming that they should get their heart rate as high as possible. This isn't the case, and hitting your highest workout heart rate ever isn't the goal.

Instead of progressively hitting higher heart rates, you actually want to see your heart rate during similar activities go down on the whole over the course of several months of heart-rate training.The stronger the heart muscle, the more blood it pumps every time it beats, therefore the fewer times it beats per minute." This, in turn, lowers your heart rate.

Making the most out of heart rate training zones comes down to two things: your goals, and your body's capabilities on any given day. If your goal is to improve your endurance, your training plan should prioritize zone 2 training, while a focus on improving power and strength might call for more intervals in zone 4.

You should always be aware of your heart rate because overexerting yourself is possible. This scenario is most common when you’re just starting out on an exercise journey. Try to take your pulse several times during your workout. You should be able to count the beats without any problem.

If your heart rate is too rapid to count, your exercise intensity is too much. Slowing down will help your fitness level. Your body is stressed when it’s overexerted, which leads to dehydration, dizziness and potential sickness. In fact, you won’t gain much from the workout except for possible injuries. Working out within a specific, heart-rate zone should always be the goal.

No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.