Heart Rates and Exercise

What are maximum and target heart rates?

Maximum heart rate (MHR) and target heart rate (THR) are values that are often used in exercise recommendations. Maximum heart rate is the estimated fastest rate at which your heart can beat during exercise. Target heart rate is the goal heart rate that you want to achieve while exercising. These values are calculated using formulas that are primarily based on age.

The formula for maximum heart rate that is commonly used is 220 minus your age. Target heart rate is usually described as a percentage of the maximum heart rate.

How are they used with exercise?

Maximum and target heart rates are used when describing different levels of exercise intensity. A common recommendation is to get 150 minutes of moderate exercise or 75 minutes of vigorous exercise per week. Moderate exercise can be defined with a target heart rate of 50 to 70% of the maximum heart rate (e.g., THR = 0.5 times MHR). Vigorous exercise can be defined as 70 to 85% of the maximum heart rate (e.g., THR = 0.85 x MHR).

Here is an example for a 50-year-old person:

Maximum heart rate

220 – 50 = 170 beats per minute

Moderate exercise target heart rate

0.5 x 170 = 85 beats per minute

0.7 x 170 = 119 beats per minute

The target heart rate range for moderate exercise is 85 to 119 beats per minute for a 50-year-old person.

Vigorous exercise target heart rate

0.7 x 170 = 119 beats per minute

0.85 x 170 = 145 beats per minute (rounded)

The target heart rate for vigorous exercise is 119 to 145 beats per minute for a 50-year-old person.

By using these values and checking one’s pulse (or using a device that shows your heart rate), you can reach the desired range of heart rate.

Should the same formulas be used for people with Down syndrome?

Differences in the function of the autonomic nervous systems of people with Down syndrome affect both the resting heart rate and the response to exercise. People with Down syndrome typically have lower maximum heart rates. One study  by Fernhall et al. recommends considering a different formula for estimating maximum heart rate of people with Down syndrome. The formula recommended for individuals with Down syndrome in the study is: MHR = 179 – (0.56 x age).

Using this formula, for a 50-year-old person with Down syndrome:

Maximum heart rate

179 – (0.56 x 50) = 151 beats per minute

Moderate exercise target heart rate

0.5 x 151 = 76 beats per minute (rounded)

0.7 x 151 = 106 beats per minute (rounded)

The target heart rate range for moderate exercise for a 50-year-old person with Down syndrome is 76 to 106 beats per minute (compared to 85 to 119 beats per minute using the traditional MHR formula).

Vigorous exercise target heart rate

0.7 x 151 = 106 beats per minute (rounded)

0.85 x 151 = 128 beats per minute (rounded)

The target heart rate for vigorous exercise for a 50-year-old person with Down syndrome is 106 to 128 beats per minute (compared to 119 to 145 beats per minute using the traditional MHR formula).

However, additional research  re-evaluated the Fernhall et al. formula and found it to have inaccuracies that seemed to be related to differences in how much maximum heart rate decreases at certain ages in people with Down syndrome compared to those without Down syndrome. The maximum heart rate declines more rapidly at certain ages in people with Down syndrome compared to others. The study recommends doing more research to develop a more accurate formula for people with Down syndrome.

Resources

Hypertension and Hypotension (High and Low Blood Pressure) (article)

References

Boer PH. Accuracy of the prediction equation for the determination of maximum heart rate in adults with Down syndrome . J Intellect Disabil Res. 2017;61(1):83-88. doi:10.1111/jir.12345

Fernhall B, McCubbin JA, Pitetti KH, et al. Prediction of maximal heart rate in individuals with mental retardation . Med Sci Sports Exerc. 2001;33(10):1655-1660. doi:10.1097/00005768-200110000-00007