Ask a Cardiologist: How High Should Your Heart Rate Get During Intense Exercise?

Getting your heart rate up is part of a healthy lifestyle. Cardiovascular exercise helps work arguably your most important muscle—your heart. However, it’s worth knowing the optimal range for your heart rate to be in so you know when you’re working hard enough and when it’s too high. 

Heart rate is measured by how many times it beats per minute. You might also call it your pulse, and it can be estimated the old-fashioned way, with your fingers on your wrist or neck while counting on a watch, or you can use a heart rate monitor or app. As you increase your activity’s intensity, your heart pumps blood at a faster rate through your body to keep up with the demand for nutrients and oxygen to your muscles. 

If your heart rate gets too high during exercise, it could be risky, especially if you’re a beginner with fitness or new to more intense exercise forms. To find out the ideal heart rate during exercise, we spoke to Sameer K. Mehta, board-certified cardiologist and President of Denver Heart, and Erin Burns, physiotherapist, osteopath, and triathlete based in Montreal.

Factors That Influence Heart Rate

Your ideal heart rate and what is considered too high or too low are all unique to you. “Many factors can influence both resting heart rate and heart rate during running. Age, fitness level, and actual heart size can all influence exertional heart rate,” says Mehta. So, it’s essential to know that there’s no cut and dried answer when aiming for a specific heart rate. Here’s how some factors can influence your heart rate, according to Burns.

Fitness Level

“The more fit you are, the more efficient the heart becomes at pumping out blood.  While training, the heart will pump more blood with each beat, therefore improving the oxygenation of the working muscles,” says Burns. So, the more you work your heart, the better it gets at pumping blood, needing to work less hard to do so, which in turn lowers your beats per minute. 

Resting Heart Rate

Your natural resting heart rate also will affect how high you should let your heart rate go during exercise. Resting heart rate can be influenced by age, weight, sex, and fitness level. “Increased fitness will lead to a lower resting heart rate due to strengthening of the heart muscles and improved cardiac output, or volume of blood pumped out with each beat,” says Burns. An elite athlete might have a resting heart rate of 40, but for most people, it will be between 60 and 100 beats per minute, with the lower end of that being ideal.

Recovery Heart Rate

“Your recovery heart rate is the decrease in heart rate one minute after exercise ceases.  With improved fitness, this number increases;  25-30 beats lower than when exercising is considered “good,” 50-60 beats lower is considered “excellent,” Burns explains. Recovery heart rate is worth noting if you perform high-intensity intervals, waiting until your heart rate returns to your normal before beginning a new interval.

Age

As you age, your maximal heart rate reduces. Although the figures are ballpark only, there are ways of calculating your ideal heart rate, and they are based on your age—more on this below.

Temperature

How hot or cold your environment is will influence your heart rate as well. Burns explains: “Heat and humidity will increase heart rate.  For every degree that the body’s temperature rises, heart rate increases by 10 beats per minute.” It’s vital to avoid intense exercise on scorching and humid days for this reason, especially if you have any heart conditions or are new to intense exercise.

Medication

“Certain medications such as beta-blockers slow the heart rate and make it more difficult to attain higher heart rates, therefore negatively influencing performance,” says Burns. Talk with your doctor if you take medications to see if intense exercise is ok for you. With beta-blockers, heart rate monitors won’t measure exercise intensity, and it’s better to go by how you feel.

Hydration

It’s vital to keep hydrated during intense exercise. “Dehydration decreases blood volume in the body and can force the heart to beat faster during exercise to deliver oxygen to working muscles. This may also lead to palpitations in more severe cases,” says Burns. If you are exercising for over an hour, or are sweating a lot, make sure to replenish your electrolytes using a supplement or drink designed for that purpose.

Stress, Lack of Sleep, Caffeine

Factors such as how stressed you are, how much sleep or recovery you’ve gotten, and if you are jacked up on caffeine will influence your heart rate. “These factors will all increase heart rate before even beginning exercise due to increased cortisol levels,” says Burns.

Medical Conditions

“Runners who have an infection, cardiomyopathy, or underlying arrhythmias such as atrial fibrillation, ventricular tachycardia will have altered heart rates during running,” Burns says. Other conditions such as obesity and diabetes can influence your heart rate as well. Be sure to discuss any medical concerns you have with your doctor.

How to Determine Your Ideal Heart Rate 

As you can tell, your ideal heart rate is dependent on many factors, so determining an ideal can take practice and self-monitoring. Mehta has this advice: “It is important to know that there is no heart rate that is necessarily too low or too high with exertion. I would base these levels more on how an individual feels. For example, when I exert myself too much, my heart rate is 180 bpm, and I feel very short of breath. In this case, training to an HR of 180 appears too high, whereas, for others, it can be normal.” 

With that said, there are methods of determining your ideal heart rate based on the maximal heart rate for your age. A simple calculation is 220 minus your age equals maximal heart rate. Two other more complicated, however perhaps more accurate formulas are:

Tanaka’s Formula (for males):

208 minus (age x 0.7) = maximum heart rate

Gulati’s Formula (for females):

206 minus (age x 0.88) = maximum heart rate

“This number is purely hypothetical since many people cannot attain their maximal heart rate because doing so is simply too uncomfortable. High-level athletes can maintain and even surpass their theoretical maximal heart rates,” says Burns.

How to Train Using Heart Rate

Putting these calculations to use in training is another matter, and it will depend on your goals. The most common way is to base your training on heart rate zones ideal for your form of exercise.

Zone 1

Zone 1 is used to promote recovery and should feel like minimal effort. Runners should be able to sustain a conversation at this intensity.

Intensity: Very light

Percentage of HR Max: 50–60%

Zone 2

Endurance and aerobic conditioning are improved in this zone. You should feel like you can sustain this effort for up to 90 minutes.

Intensity: Light

Percentage of HR Max: 60–70%

Zone 3

Commonly referred to as the “tempo” pace, this zone improves blood circulation efficiency to working muscles. Working in this zone will also help to make moderate efforts feel easier. However, spending too much time in this zone with insufficient periods in lower zones can lead to injury. This occurs because the body does not have enough time to adapt to the normal breakdowns during more demanding training that allows for eventual gains in strength and fitness.

Intensity: Moderate

Percentage of HR Max: 70–80%

Zone 4

Running in this zone for intervals of up to several minutes will improve speed endurance. Breathing will be difficult, and the muscles will begin to burn. Once again, it is essential to vary speed within a workout, alternating between zones 1-2 and zone 4 to maximize gains and reduce the chance of injury.

Intensity: Hard

Percentage of HR Max: 80–90%

Zone 5

This maximal effort cannot be sustained for more than five minutes before the body will naturally slow down. Generally, training in this zone is reserved for runners who already have an established base and should be avoided when starting.

Intensity: Maximum

Percent of HR Max: 90–100%

In the case of running, for example, Burns says that ideally, a training week consists of: 

• Speedwork (intervals): zones 4-5
• Tempo run: zone 3
• Long run: zones 1-2
• Easy run(s): zone 1

The time and distance for each of these workouts will vary depending on race goals, experience, age, and fitness levels, and it’s best to consult with a certified coach or recognized training plan to optimize preparation.”

Mehta agrees, adding: “I would evaluate several training programs to help decide how much of my workout is dedicated to a particular level; in general, spending most of your time in Zones 2 and 3 allows for further cardiovascular gains.” So, tracking and monitoring your progress is key.

How to Tell if Your Heart Rate is Too High

“In individuals with underlying cardiac disease, prolonged intense exercise can lead to sudden cardiac arrest,” says Mehta. These runners can be very well trained and may not even be aware of their condition until this unfortunate event occurs. But for the average person, training with a high heart rate is perfectly safe within limits. Mehta adds: “In general, there is nothing dangerous if running at a high heart rate for an extended period.” However, there are some signs to be aware of when exercising at high heart rates.

Signs that your heart rate is too high include: 

• Hyperventilation
• Chest pain
• Dizziness or feeling faint
• Nausea
• Headache
• Palpitations

How to Check Your Heart Rate

The simplest way to check your heart rate is to use a heart rate monitor. “Heart rate monitors give immediate feedback to ensure that the training zones are being respected. They can also be useful for runners with certain medical restrictions who must control their maximal heart rates,” says Burns.

Heart rate monitors have another useful function when you are not exercising. “They are excellent for measuring resting heart rate before getting out of bed in the morning to screen for overtraining. A person in an overtrained state will have a higher resting heart rate than normal,” explains Burns. 

Checking heart rate without a heart rate monitor is simple. Burns instructs: “Stop exercising briefly, palpate the carotid artery on the neck, and count the number of beats for fifteen seconds. Multiply this number by four.”

The Takeaway

Although it can seem complicated, monitoring your heart rate is an excellent way to gauge your progress and fitness level. Setting goals and training parameters around your heart rate will help you make exercise sessions uniquely tailored to your abilities. Just be cautious of overtraining or exercising at unsafe levels. Always listen to your body and take it down a notch if something feels off.