Why does my heart rate get so high during exercise

Heart rate is an indicator of exercise effort and physical fitness, but it doesn’t tell the whole story. Your age and other medical conditions play a role, too.

The heart is an amazing muscle that beats nonstop its whole life. Its main job is to circulate blood and oxygen to the body, and it adjusts how much it pumps based on what your body needs. During exercise, muscles need oxygen and sugar for energy — and they get those nutrients from blood. 

So the heart’s ability to deliver blood to the muscles is an important part of physical fitness. This is why the heart pumps faster — increasing your heart rate — when muscles need more fuel. 

Why is heart rate important for exercise? 

In general, the harder your muscles are working, the higher your heart rate. So people track their heart rate during exercise as a measure of exercise intensity. But there are many reasons someone may want to know how hard their body is working, like:

• Improving physical fitness: Someone who is trying to increase their physical fitness may aim for a certain heart rate during their workout. This way, they know their heart is working hard enough.

• Training for an event: Someone can use their heart rate to help them train for a specific event. So a marathon runner may want to keep their heart rate at their marathon pace when out for a run. 

• Staying in a safe range: Someone may want to monitor their heart rate to make sure it stays within a safe range for them. This might be true for someone who is exercising in extreme heat or recovering from a heart attack.

It’s especially important to track heart rate if you have heart disease. Healthy hearts can adjust and recover quickly from intense exercise. People with a heart condition need to be more mindful of how fast their heart is pumping. If their heart rate gets too high, it can affect blood flow through the heart. And this can lead to symptoms — like chest pain — or even injury to the heart muscle. 

All hearts benefit from exercise, but the intensity should be adjusted for the individual. And heart rate is one of the easiest ways to measure that intensity. 

What is the average heart rate during exercise?

Your age is the most important determinant of your ideal heart rate during exercise. For most adults, a normal resting heart rate is about 60 to 100 beats per minute (BPM). When it comes to exercise, there are actually two averages to think about.

Maximum heart rate 

Maximum heart rate is the highest rate your heart can go. It’s defined as 220 minus your age. So if you’re 50 years old, your maximum heart rate is 220 minus 50, or 170 BPM. People of the same age may vary a little bit in their maximum heart rates, but the calculation is surprisingly accurate for most people.

Target heart rate

Target heart rate is the heart-rate range you sustain during exercise. Target heart rate is calculated as a percent of your maximum heart rate. And it depends on the level of intensity you’re aiming for.

What should your target heart rate be when exercising?

Your target heart rate depends on your age and the type of exercise intensity you’re aiming for. You can calculate your target heart rate as a percentage of your maximum heart rate:

• Moderate-intensity exercise: This is 50% to 70% of your maximum. So, in the example above, someone who is 50 years old would keep their heart rate in the 85 to 119 BPM range during moderate exercise.

• High-intensity exercise: This is 70% to 85% of your maximum. In the example above, vigorous exercise would keep the heart rate between 119 to 145 BPM.

So how do you know what level of intensity to shoot for? According to the latest research, healthy adults should aim for the following per week:

• A minimum of 2.5 to 5 hours of moderate-intensity exercise or 1.25 hours of high-intensity aerobic activity (or a combination of both)

• At least two, full-body, muscle-strengthening activities of moderate intensity or greater

But it’s important to remember that these should be customized for your needs — especially if you have a history of heart disease, take medications that affect heart rate, or have other exercise limitations. 

It's possible to achieve your intended intensity and target heart rate with a broad range of activities — from walking or playing sports to weight lifting. No matter what kind of exercise you do, a wearable heart rate monitor or simple pulse check can keep you on target during your workout.  

Who should be careful about their heart rate while working out?

Most people can exercise without any limitations. They can do high-intensity exercise and feel good about the way it improves their health and fitness — without any risks.  But there are some conditions that can lead to health complications with heavy exertion. 

It’s always a good idea to visit a healthcare provider for a regular checkup if you plan to start a new exercise program. A high heart rate, which comes naturally with exercise, can strain the heart if your circulation is not performing at its best. People have an increased risk for a heart or circulation problem if they have:

• A history of smoking can cause narrowing of arteries in the heart and throughout the body.

• A high body weight can predispose someone to circulation problems and high blood pressure.

• Diabetes is a risk factor for cardiovascular disease.

• High cholesterol directly contributes to atherosclerosis.

• Heart disease, like irregular heart beats, heart attacks, or decreased pump function (heart failure), increases risk.

• High blood pressure can lead to long-term damage to arteries. It can also make it harder for the heart to pump blood to muscles and vital organs during exercise.

Exercise is an important part of the treatment for all of these conditions. And not getting any exercise is riskier than exercise itself. All the same, if you have one of these conditions, it’s helpful to know the type of exercise that is safest for your body. You can modify any exercise to fit your needs — from low-impact activities to reduced exercise time or intensity.

What is considered a dangerous heart rate?

In general, your heart rate should not go higher than your maximum heart rate based on your age. But, if you have underlying health conditions, your maximum rate may be a little bit lower than this. 

There’s no magic formula that can figure out what is a dangerous heart rate for you. But the answer may be simpler than you think — listen to your body. 

Your body will tell you when your exercise intensity is too high. Exercise will feel hard. But if you feel chest pain or like you can’t catch your breath, these could be signs your heart is not getting enough blood. Headache or dizziness can be signs your brain is not getting enough blood.   

A dangerous heart rate is: 

If something seems unusual to you, don’t push it. Lower your exercise intensity or give your body a chance to rest. And if it happens more than once, it’s best to get checked out. It’s important to see a healthcare professional about any of these symptoms related to heart rate.

The bottom line

Your heart rate is designed to change in order to deliver the right amount of blood to the body, depending on activity levels. Exercise is intended to cause the heart to pump faster to help it grow stronger. But every person has a different threshold for when this is safe and beneficial and when it is dangerous and potentially harmful. 

Target heart rates can help with fitness goals, and monitoring your heart rate during exercise can be a good alert system. But, most importantly, listen to your heart — it will tell you when you’re on target and when it’s time to slow down and ask for some help. 

GoodRx Health has strict sourcing policies and relies on primary sources such as medical organizations, governmental agencies, academic institutions, and peer-reviewed scientific journals. Learn more about how we ensure our content is accurate, thorough, and unbiased by reading our editorial guidelines.

Was this page helpful?

thumb_up_outlinedthumb_down_outlined

Subscribe and save.

By signing up, I agree to GoodRx's Terms and Privacy Policy, and to receive marketing messages from GoodRx.

What is a dangerously high heart rate during exercise?

Why is my heart rate always high during exercise?