As you get ready to step into your sneakers and put on your smartwatch before exercising, you might notice the heart rate sensors on your watch are keeping track of how much time you spend in different heart rate zones.
Heart rate zones can be an exciting type of exercise data – but also confusing if you don’t know what your body is doing in each zone.
Cesar Nava and Anna Majek are certified athletic trainers with Rochester Regional Health and explain what heart rate zones are, the role they play in aerobic exercise, and what you need to know about keeping your heart and body healthy.
Calculating heart rate zones
During aerobic activities like running, walking, biking, or taking an exercise class, the body’s heart rate increases as your body tells the heart to send more oxygen-rich blood around the body. The higher your heart rate, the harder your heart is working.
Heart rate zones are a way of determining your heart’s level of effort during aerobic activity. These zones are determined by finding a person’s resting heart rate and their maximum heart rate, then dividing the beats per minute (BPM) into 5 zones.
According to the American College of Sports Medicine, a person’s maximum heart rate is calculated by the following formula:
220 – [your age in years] = maximum heart rate
A person’s resting heart rate is calculated by timing their pulse over the course of one minute.
Zone 1: Warm-up and recovery
This zone is approximately 50-60 percent of a person’s maximum heart rate.
Zone 2: Baseline aerobic activity
This zone is approximately 60-70 percent of a person’s maximum heart rate.
Zone 3: Moderate aerobic activity
This zone is approximately 70-80 percent of a person’s maximum heart rate.
Zone 4: Intense aerobic activity
This zone is approximately 80-90 percent of a person’s maximum heart rate.
Zone 5: Short, intense bursts of activity (anaerobic)
This zone is approximately 90-100 percent of a person’s maximum heart rate.
Zones 1-3 usually feel like a “good workout” where you are not out of breath and can maintain a good level of effort. Zone 4 begins to feel more intense as the heart rate increases and breathing becomes more labored. Zone 5 – usually experienced in short, intense spurts of effort – is when you are pushing your body the hardest.
Internally, when your heart rate is in zones 1-3, the body tends to burn more fat to produce energy. When your heart rate gets up into zones 4 and 5, the body burns more carbohydrates and proteins. Not everyone needs to get their heart rate up to Zone 5 during every exercise activity.
“It all depends on what your goals are,” Majek said. “Different heart rate zones accomplish different things.”
“If your goal is to become more heart healthy, then about 85 percent of your workout should be in Zones 1-3, 10 percent in Zone 4, and 5 percent in Zone 5,” Nava said.
Heart rate accuracy on smartwatches
Smartwatches produced by companies such as Apple, Garmin, and Samsung have optical sensors that detect your heart rate by shining lights through your skin and measuring the movement of blood through blood vessels.
The technology is newer than other forms of technology like heart rate straps that place sensors on the chest and measure electrical activity produced by the heart. Chest straps are slightly more accurate because of where they are placed and the type of activity they measure, but optical sensor technology placed on the wrist is constantly improving.
A recent study from the American Heart Association suggests new software algorithms used in smartwatches might be able to help detect irregular heart rhythms – including atrial fibrillation.
Listening to your body
While heart rate zones determined by smartwatch sensors are helpful for monitoring how well your body performs while you’re exercising, being in tune with your body can produce similar results.
By paying close attention to your breathing, ability to hold a conversation, level of muscle fatigue, and other factors, your body can show you how hard your heart is working during physical activity.
The better you know your body and how it behaves during exercise, the more ready you will be to react if something needs to be changed.
“Keep your heart rate in your mind for the sake of your own health,” Majek said. “It’s good to keep track of that data because if something starts to change in the pattern of your heart rate, something might be changing with your health.”
Related Articles
