Family YMCA of Black Hawk County



How do they work?


Smartwatches and Tracking Your Heart Rate during a workout.

Rhett Turner, M.A., ACE-CPT, USAW-SPL1

With a staggering 25% of adults not meeting recommended guidelines for physical activity, physical inactivity has been identified as the fourth leading cause of human mortality  (Murakami et al., 2016). Exercise and physical activity has been shown to hold a multitude of benefits including longevity of life, decreasing the risks of various diseases, increases in energy, elevating mood, increasing muscle mass, and improving overall health.  The benefits of exercise are substantial and should not be ignored! With technology so heavily integrated into today’s society, smartwatches (such as the apple watch, fitbit, garmen, etc.) can assist users with weight management, tracking aerobic exercise, and tracking heart rate.

Manually taking one’s heart rate at the radial (wrist) or carotid (windpipe just below jawbone) arteries have been identified as the gold standard for heart rate tracking.  However, this may be inconvenient because it typically requires folks to stop what they are doing and focus to get an accurate heart rate count. Today, smartwatches are now a billion dollar industry.  Wearable technology to monitor physical activity has been ranked first in 2016 and 2017 and is projected to continue as a fitness trend in the future (Boudreaux et al., 2018).

In the 1980s devices like Polar Heart Rate Monitors found their way into fitness.  These devices come with a strap that wraps around your chest and use electrodes to monitor the electrical activity of the heart, very similar to an ECG (Murakami et al., 2016; Etiwy et al., 2019).  However, the public never adopted these devices because they are generally uncomfortable and inconvenient. Now, devices made by Apple, FitBit, and Garmin have made their way into the industry. These devices measure heart rate by a method known as optical heart rate monitoring (photoplethysmography).  Unlike an ECG, these devices illuminate the skin with light emitting diode and then measure the amount of light reflected back to the photodiode sensor. This enables detection of variations in blood volume associated with the pulse that comes from every heart contraction.

Wrist devices have been shown to enhance physical activity levels and promote weight loss (Boudreaux et al., 2018).  They have been found to be 91.8% accurate during cycling events while only being 34.5% accurate during resistance exercise.  The discrepancy here may be attributed to the major flaw of these devices. Misalignment of the device or motions that come along with high intensity exercise can lead to inaccurate heart rate measurements.  If you’re using one of these devices make sure to wear it snug, but comfortable.  

Generally speaking, these devices can be reliable to the general public for fitness tracking.  They are flashy, easy to operate, and can give reliable feedback if worn correctly. If heart rate is an integral part of your training program, it is recommended to use devices such as Polar which are able to get a more accurate reading compared to their smartwatch counterparts.


Boudreaux, B., Hebert, E., Hollander, D., Williams, B., Cormier, C., Naquin, M., Gillian, W., Gusew, E., Kraemer, R. (2018).  Validity of wearable activity monitors during cycling and resistance exercise. Med Sci Sports Exerc., 50(3), 624–33.

Etiwy, M., Akhrass, Z., Gillinov, L., Alashi, A., Wang, R., Blackburn, G., Gillinov, S., Phelan, D., Gillinov, A., Houghtaling, P., Javadikasgar, H., & Desai, M. (2019).  Accuracy of wearable heart rate monitors in cardiac rehabilitation. Cardiovascular Diagnosis and Therapy, 9(3), 262-271.

Murakami, H., Kawakami, R., Nakae, S., Nakata, Y., Ishikawa-Takata, K., Tanaka, S., Miyachi, M., Accuracy of wearable devices for estimating total energy expenditure: comparison with metabolic chamber and doubly labeled water method.  JAMA Intern Med. 2016;176(5):702-703.

Get Involved

The YMCA isn’t ONLY about getting in shape. It is a community resource organization, aimed at improving the spirit, mind, and body of all who want to participate.

Make a Gift

We need your support to strengthen our community – because strengthening community is our cause.
Learn More

Proud Partners