What You Need to Know About Your Heart Rate During Exercise
This content is brought to you in partnership with OrthoCarolina, one of the nation's leading orthopedic practices with offices across the Southeast.
According to a 2020 study from the Pew Research Center, about one in five Americans use a smart watch or fitness tracker. If you're one of them, then chances are you're familiar with your resting and active heart rate, as measured by your tracker of choice.
But how much do you really know about what that number means, as it pertains to your health and wellness goals?
We spoke with Sean Brown — a PT, DPT, OCS, and CSCS at OrthoCarolina — to learn everything we need to know about our heart rates during exercise.
The Basics: Heart Rate and Cardiac Output
Brown started by covering the basic terms you should know as we discuss heart rate.
"The heart pumps blood in order to deliver oxygen-rich blood to working tissues and remove carbon dioxide from the body," Brown explained. "The amount of blood the heart pumps during a minute is called cardiac output. The amount of blood the heart pumps during each beat is called stroke volume."
Brown went on to explain that cardiac output is calculated by multiplying a person’s heart rate by their stroke volume — and as you might expect, cardiac output increases as a person’s workload (aka exercise intensity) increases.
Heart Rate: Considerations for Exercise
We spoke with Brown to learn more about the variety of factors that go into an individual’s heart rate during exercise.
"A person’s maximum heart rate will decrease with age," he said. "Though this is a rough formula, a person’s maximum heart rate can generally be estimated by 220 minus their age."
For example, if you were 27 years of age, your maximum heart rate might be calculated at 193. Meanwhile, if you were 67 years of age, your maximum heart rate might be calculated at 153.
"Because of this, having generic heart rate values for exercise should not be utilized, as the workload for a given workout will be different for individuals with different ages," Brown cautioned.
He added that the heart rate for any given workload will decrease as a person improves their fitness.
As he put it, "Performing a certain workload later during an individual’s training plan may result in a heart rate that is lower than it will be later in their training plan."
Brown also noted that your heart rate will tend to increase more quickly when exercising in hot and humid environments, even as your workload decreases.
"This is a result of dehydration, and the resulting reduction in blood volume. As blood volume decreases, so does stroke volume," he explained.
Like we mentioned above, cardiac output = heart rate x stroke volume.
"So, as stroke volume decreases due to heat and humidity, your heart rate must increase in order to accommodate the required cardiac output," Brown said.
Last but not least, Brown noted that exercising large muscle groups will tend to produce larger changes in heart rate compared to exercising small muscle groups.
An example of bigger muscle groups would be your hamstrings, glutes, quadriceps, back, and chest. Meanwhile, your smaller muscle groups would consist of shoulders, triceps, biceps, and calves.
Learn more about making healthy choices from the experts at OrthoCarolina
Whether you've recently experienced an injury, need help with recovery after tough workouts, or are simply experiencing chronic pain and need help managing it, OrthoCarolina can help. Make an appointment at a location near you to start getting the treatment you need.