If you’ve ever used a smartwatch, fitness tracker or workout app, you’ve likely seen references to “heart rate zones.” These zones are designed to measure exercise intensity and can help improve fitness, endurance and overall heart health.

But what exactly do heart rate zones mean, and do you really need to pay attention to them during workouts? Nebraska Medicine cardiology fellow Sumant Pargaonkar, MD, has personally trained using heart rate zones for years. Here’s what he wants people to know.

What are heart rate zones?

Heart rate zones are ranges based on how fast your heart is beating during exercise compared to your estimated maximum heart rate. In general, the zones range from one to five, with zone one representing very light activity and zone five representing maximum effort.

A common way to estimate your maximum heart rate is by subtracting your age from 220. For example, a 50-year-old would have an estimated maximum heart rate of about 170 beats per minute.

From there, heart rate zones are divided into percentages:

• Zone 1: 50% to 60% of max heart rate. 
• Zone 2: 60% to 70% of max heart rate. 
• Zone 3: 70% to 80% of max heart rate. 
• Zone 4: 80% to 90% of max heart rate. 
• Zone 5: More than 90% of max heart rate. 

Different fitness apps and devices may use slightly different ranges, but the overall concept remains the same: lower zones represent lower-intensity exercise, while higher zones reflect more intense effort.

“These zones help estimate how intensely your body is working and what type of energy systems you are using during exercise,” Dr. Pargaonkar says.

Are heart rate zones the same for everyone?

Age, fitness level, medications and overall health can all affect heart rate response during exercise. For example, trained athletes often have lower resting heart rates, while medications such as beta blockers can prevent someone’s heart rate from rising as high during activity.

Heart rate response can also vary depending on the activity. 

“For example, heart rates during swimming are often lower than when someone is running at the same perceived effort because their body is supported horizontally in the water,” Dr. Pargaonkar says.

Which heart rate zone is best?

“There is no single ‘best’ zone for everyone,” Dr. Pargaonkar says. “The biggest health benefit comes from moving from a sedentary lifestyle to regular physical activity.”

That said, Zone 2 training has become especially popular because it focuses on steady, light- to moderate-intensity exercise that can be sustained comfortably for 40 to 60 minutes. Examples include brisk walking, jogging, cycling and swimming.

Zone 2 workouts are commonly recommended for:

• Building endurance.
• Improving cardiovascular fitness.
• Supporting weight management goals.

Some fitness trackers refer to Zone 2 as the “fat-burning zone” because the body uses a higher percentage of fat for fuel at lower intensities. However, higher-intensity exercise can still burn more total calories overall. Experts generally recommend a mix of exercise intensities rather than focusing on only one zone.

“Any exercise is better than none,” Dr. Pargaonkar says. “Zone 2 training is popular because people can sustain it over time without feeling exhausted, but higher-intensity exercise can also provide benefits depending on a person’s fitness level and goals.”

How do you know if your heart rate is too high during exercise?

There is no single number that applies to everyone, but certain symptoms during exercise may signal that you are overexerting yourself. In general, it’s best to stop exercising and seek medical attention if you experience:

• Chest pain, pressure or tightness. 
• Dizziness or fainting. 
• Severe shortness of breath. 
• Heart palpitations or irregular heartbeat. 
• Nausea or vomiting. 

How much exercise do you need?

The American Heart Association recommends at least 150 minutes of moderate-intensity exercise per week, 75 minutes of vigorous exercise per week or a combination of both to support cardiovascular health and reduce the risk of chronic disease.

“The most important thing is to move more and sit less,” Dr. Pargaonkar says. “For people who are already active, aiming for at least 150 minutes of moderate-intensity exercise each week can further improve cardiovascular health.”

Regardless of your goals, Dr. Pargaonkar recommends gradually increasing intensity instead of jumping immediately into all-out efforts.

“Warming up gradually allows your heart and blood vessels time to adapt to increasing demand, which can help prevent symptoms like dizziness, lightheadedness, nausea or vomiting,” he says.