Low intensity heart exercising can help improve your endurance, though it may take longer to achieve your fitness goals than traditional high heart rate training.

You may have read or heard that to get the most out of your running or other aerobic workouts, your target heart rate should be about 75% of your maximum heart rate. But high intensity workouts can trigger heart problems, especially for those who aren’t used to that type of exercise.

With low intensity heart exercising, your heart rate is still high — just not as high as it might be with traditional high heart rate training.

Low intensity heart exercising reduces the risk of overdoing it while still improving your cardiovascular fitness. The idea is to keep your heart rate from jumping too high while you’re exercising to be able to work out for longer and more safely.

Running coach Phil Maffetone developed low intensity heart training as a way to build endurance among his runners. The principles can also apply to cycling, swimming, and other aerobic exercises.

Low intensity heart training means you’re running or exercising at a slower pace, which prevents your heart rate from climbing too high.

Over time, your heart and lung capacity improves, and your body becomes more efficient in how it uses energy.

The goal of low intensity heart training is that you’ll one day resume your usual pace but will do so with a heart rate lower than it would’ve been without low intensity heart training. This approach allows you to train with a lower risk of straining your heart.

There are various formulas for determining your target heart rate and your ideal low heart rate for training. These approaches are based on what your maximum heart rate should be for your age.

According to the Centers for Disease Control and Prevention (CDC), you can work out your ideal maximum heart rate by subtracting your age from 220.

With low intensity heart training, you subtract your age from 180 instead. This number becomes the heart rate you should use as your maximum during your workouts.

For example, if you’re 50 years old, you would subtract 50 from 180 and arrive at 130. Your target heart rate for low intensity heart training would then be 130 beats per minute and no higher.

The main benefit of low heart rate training is being able to run or do other aerobic exercises at your normal pace but with a lower heart rate. This places less burden on the heart muscle while also improving your endurance.

A 2019 study compared two types of training: focused endurance training (FOC) and polarized endurance training. In the FOC group, the runners spent more of their training time exercising with higher heart rates and at a greater intensity. In the polarized endurance training group, the runners spent the majority of their workouts running at a slower pace with a lower heart rate.

The researchers found that fitness improvements were similar between the two groups, but the FOC group was able to achieve those results in a shorter time.

How long it takes for low heart rate training to produce noticeable benefits will vary from one person to another. However, a 2021 study suggests that 1 hour of low intensity training twice a week could start to lead to improved endurance after just 4 weeks.

To get back to your usual running pace but at a lower heart rate, you may need to maintain your low heart rate training for at least 2–3 months.

While any movement at any pace is better than being sedentary, you do need to get your heart rate up to achieve cardiovascular benefits.

The American Heart Association (AHA) recommends that people starting out should aim for around 50% of their maximum heart rate (220 minus your age), then build up slowly. Less than 50% of your maximum may not give you the cardiovascular benefits you want or need.

If you have a low heart rate at rest or when exercising, it may be because you’re in exceptional condition and your heart simply beats efficiently.

However, a low heart rate can also point to a cardiovascular concern, such as an unusually slow heart rate (bradycardia). Bradycardia can also keep your heart from beating fast enough to accommodate the demands of exercise.

Exceeding your maximum heart rate while exercising may harm your heart and cause problems such as heart rhythm disturbances (arrhythmia).

Exercising at a slower pace in order to maintain a low heart rate is generally safe for most people.

However, if you have a heart condition — such as a history of heart attack or stroke, arrhythmia, heart failure, or another concern — you should talk with your doctor before doing any type of exercise.

Your doctor may recommend that you participate in a supervised cardiac rehabilitation program to learn how to exercise safely and effectively.

To get started with a low heart rate training plan, you’ll need to determine your low heart rate number.

For best monitoring results, use a chest strap that will constantly check your heart rate while you’re running or working out. If you find your heart rate exceeding your target rate, slow down and walk if necessary. This will take some getting used to, but soon, you’ll learn how much exertion puts you in your target range.

The number of miles you run or the amount of time you spend exercising is up to you and your current fitness level.

If you usually run 3 miles, aim for 3 miles, but always with the caveat that you won’t exceed your low heart rate goal.

Initially, you may need to reduce your miles or your time spent exercising if your heart rate wants to rise as you work out.

If doing any running quickly sends your heart rate above your target, scale back to a brisk walk.

Keep in mind that committing to a low heart rate training plan means that all of your workouts, including strength training and other exercises, need to be done at your low heart rate target. As your body gets used to staying at a lower heart rate when exercising, you’ll soon be able to ramp up your workout intensity.

For people who run or do other aerobic exercises on a regular basis, starting up a low heart rate training program may be frustrating at first. It means taking it slower than usual and carefully monitoring your heart rate so that it doesn’t climb too high.

But if you stick with it for a few months, you may find that you’ll be back to moving at your usual speed but with your heart working at a more relaxed rate than it was before you changed your training routine.