The target-heart-rate range is a helpful guide for monitoring exercise intensity. It should take into account an individual's fitness level, habitual exercise routine, medical history, goals, and overall program.
Exercise increases the demand on the body and heart, which causes the heart to beat faster. The target heart rate is a guide to how quickly the heart should beat during exercise. Calculating a targetheart–rate range helps an individual estimate intensity of exercise and work out more safely and effectively. Once the target heart rate has been calculated, exercisers should monitor their pulse during exercise and compare it to the range to make sure the exercise effort is appropriate. The exercise intensity can then be adjusted accordingly.
For example, if individuals have calculated their target-heart–rate range as 130–160 beats per minute and check their pulse during exercise to find it is lower than 130 beats per minute, the exercise is probably not challenging enough to be beneficial. Depending on their medical history and fitness level, heart rates over 160 beats per minute might be too high to be safe. Thus, the target-heart-rate range is used to guide the intensity of the exercise program.
The target heart range, also called training heart range, is calculated based on the predicted or estimated maximum heart rate for a person's age and desired level of exercise effort. For most people, a level of effort at about 50%–85% of maximal heart rate is suggested.
Factoring in resting heart rate, which helps to calculate a “heart rate reserve,” tends to be a little more accurate. In general, the higher the heart rate, the more challenging the exercise, and the greater the metabolic demands on the body. This holds true for most types of cardiovascular exercise, such as running, walking, biking, stair climbing, hiking, and using many types of indoor exercise equipment, such as elliptical equipment and stationary cycles. Target heart rate is not an appropriate method to monitor the intensity of a weightlifting program.
Individuals can calculate their own target heart rate by subtracting their age from the number 220 to find their average maximum heart rate and then determining the 50%–85% range of the maximum. As an example, a person who is 40 years old has a maximum heart rate of 180 beats per minute and a target rate of 90–153 beats per minute.
After several minutes of warm up, and once the desired exercise level is achieved, an exerciser, some pieces of equipment, or a wireless monitor can measure pulse. While continuing to exercise, the pulse is counted for 10 seconds and multiplied by six. This number equals heart rate in beats per minute and should fall within the target-heart–rate range. If it is below the range calculated, the exercise might be too easy. If it is higher than the range, the exercise might be too challenging to be sustained or safe. This process should be repeated periodically throughout the workout and whenever a person changes the type of exercise being done, for example, goes from a treadmill to a bike.
It is important to realize that exercise intensity, which is gauged by heart rate, and exercise duration, minutes spent exercising) are interrelated. Target heart rate is a range, not one number, and likewise, the exercise program parameters are best thought of as a spectrum. For example, exercising for 50 minutes at the lower end of the target heart rate is beneficial, but so is exercising for 20 minutes at the higher end. Because intensity and duration are interrelated, both need to be considered in the exercise prescription. Likewise, for weight loss, use of interval training, or short bursts of vigorous-intensity exercise mixed with low-intensity exercise, can burn more calories than a steady pace.
A runner going out for a 4-mile (6.4-km) run might shoot for a heart rate near 85% of her maximum by increasing her pace, but might run at a slower pace that elicits 60% of her maximum when she is out for a 10-mile (16-km) run.
In certain cases, age-predicted maximal heart rates or target-heart–rate ranges are not appropriate. Age-predicted maximal or training heart rates should not be used for individuals taking beta blockers or other medications that lower heart rate; people who are diabetic with autonomic neuropathy; or individuals who have an irregular heart rate, such as atrial fibrillation. Pregnant women should be cautious about using a target heart range to gauge exercise intensity because heart rate varies widely when pregnant.
Age-predicted maximum heart rate is an estimate, not an exact science. Although this calculation works well for most people, it is not precise for all people. The only way to know an individual's maximal heart rate with certainty is by having a maximal exercise test.
Individuals using target heart rates to guide exercise intensity should not be misled by heart rate charts posted on equipment and gym walls. Many of these charts and posters incorrectly designate a “fat-burning zone” at the lower end of the target-heart-rate range. In actuality, more total calories and fat are burned at higher exercise intensities (higher heart rates). This is because higher exercise intensity places a greater metabolic demand on the body both during and after exercise.
To use the target heart rate it helps to practice counting the pulse while exercising. Waiting until exercise is over to count pulse is not advised because the heart rate tends to drop quickly, and this could lead the individual to think that the intensity needs to be increased when it does not. Alternatively, a heart rate monitor can be purchased and worn during exercise. These devices usually employ a chest strap or watch, and provide a constant heart rate during exercise.
Individuals using heart rate range to guide exercise intensity must be able to monitor their pulses correctly. If the exercise feels very difficult, but the heart rate is low, they might not be measuring correctly or might be waiting until exercise is over before measuring. Some studies indicate that heart rate decreases about five beats per minute every 10 seconds after stopping exercise. Even people who have received instruction on pulse measurement take 15–20 seconds to obtain a heart rate after they stop exercising. Therefore, counting pulse during exercise is recommended if at all possible.
Using a target-heart-rate range allows an individual to guide intensity during exercise so that the program is safer and more effective. As fitness improves, it takes harder exercise to elicit the same heart rate. In this regard, monitoring heart rate is a great way to see progress and to know when the program needs to be updated.
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American College of Sports Medicine, 401 W. Michigan St., Indianapolis, IN, 46202, (317) 637-9200, Fax: (317) 634-7817, http://www.acsm.org .
American Council on Exercise, 4851 Paramount Dr., San Diego, CA, 92123, (858) 576-6500, Fax: (858) 576-6564, (888) 825-3636, firstname.lastname@example.org, http://www.acefitness.org .
American Heart Association, 7272 Greenville Ave., Dallas, TX, 75231, (800) 242-8721, Review.email@example.com, http://www.heart.org .
Lisa S. Womack, MEd
Revised by Teresa G. Odle, BA, ELS