Heart rate zones are not a perfect indicator of exercise intensity, but getting your heart rate up regularly is still critical for staying fit

The primary way to stay fit is aerobic exercise such as running, cycling, swimming or hiking. circulatory health and general healthThe intensity of your aerobic exercise is critical to determine how much time you should devote to your workout to benefit from it.

As exercise science researcherI support American College of Sports Medicine Recommendation at least 150 minutes per week of moderate aerobic exercise or 75 minutes per week of vigorous intensity exercise. But what does exercise intensity mean?

There is linear dependence between heart rate and exercise intensity, meaning that as exercise intensity increases, so does heart rate. Heart rate zone training, which uses heart rate as a measure of exercise intensity, has has gained popularity in recent yearsdue in part to the ubiquity of wearable heart rate technology.

Exercise intensity method usually described is problematic because what is “intense” for one person may be “moderate” for another. Heart rate zone training attempts to provide an objective measure of intensity by dividing it into different zones. However, heart rate can also be affected temperature, medication and stress levelwhich may affect readings during exercise.

Heart rate and exercise intensity

This the gold standard for determining aerobic exercise intensity involves measuring the amount of oxygen consumed and carbon dioxide exhaled. However, this method is cumbersome because it requires people to wear a breathing mask to capture respiratory gases.

An easier way is to predict a person’s maximum heart rate. This can be done using equation by subtracting the person’s age from 220. Although there is controversy over the best way to calculate maximum heart rate, researchers suggest this method is still valid.

American College of Sports Medicine presents five heart rate zones based on an individual’s predicted maximum heart rate. Zone 1, very delicate intensity, equals less than 57% of maximum heart rate; zone 2, delicate intensity, is 57% to 63%; zone 3, moderate intensity, is 64% to 76%; zone 4, vigorous intensity, is 77% to 95%; zone 5, near maximum intensity, is 96% to 100%.

However, other organizations have their own exercise intensity measures, with different ranges and descriptions. For example, The Orange Theory describes his Zone 2 workout as 61% to 70% of your maximum heart rate. To complicate matters even more, heart rate monitor companies also have higher thresholds for each zoneFor example, Polar Zone 2 covers up to 70% of your maximum heart rate, while the American College of Sports Medicine recommends zone 2 at 63%.

Customizing your heart rate zones

Zone training is based on the assumption that the way the body responds to exercise is at least partly depends on the intensity of exerciseThese adaptations include increased oxygen consumptioncritical cellular adaptations AND improving exercise performance.

Zone 2 has attracted a lot of attention from the fitness community due to its possible benefitsPerformance trainers describe zone 2 as “delicate cardio,” where the intensity is low and the body relies primarily on fat to meet its energy needs. Fats provide more energy compared to carbohydrates, but deliver it to the cells slower.

Since there is more fat than carbohydrate in the body, the body responds to cellular stress that physical exercise causes muscle cells increasing the number of mitochondriaor the energy-producing component of cells. By increasing the number of mitochondria, the body can become better at burning fat.

At the other end of the exercise intensity spectrum is high intensity interval training, or HIIT. These workouts involve high-intensity exercise for a low period of time, such as sprinting or cycling for 30 seconds to a minute, followed by a period of low-intensity activity. This is repeated six to 10 times.

During this type of high intensity activity, the body primarily uses carbohydrates as a fuel source. During high intensity exercise, the body preferentially uses carbohydrates because energy requirements are high and carbohydrates provide energy twice as swift as fats.

Some people who start exercising to lose fat may avoid high-intensity training in zone 2 because it is considered the “fat burning zone.” This may be a misnomer.

The researchers found that high-intensity interval training caused similar increases in markers mitochondria production compared to longer, moderate aerobic exercise. Studies have also shown that people who exercise at high intensity build muscle and improve insulin resistance AND cardiovascular health similar to those exercising at moderate intensity, and achieved these benefits more quickly. The main trade-off was discomfort during periods of high-intensity exercise.

Moderate or high intensity exercise?

With varying guidelines for heart rate zones and conflicting evidence on the potential benefits of training in each zone, exercisers may be confused about what to do.

To get the health benefits of exercise, the most important variable consider sticking to an exercise routine, regardless of intensity. Because the body adapts similarly to moderate and high-intensity exercise, people can choose which intensity works best for them and which works least for them.

Note that the American College of Sports Medicine’s exercise recommendations are in the moderate-intensity range. This is equivalent to zone 3, or 64% to 76% of your maximum heart rate, a range that can only be reached at the upper end of most zone 2 workouts. If you’re not seeing the results you want with zone 2 workouts, try increasing the intensity to reach a moderate level.

The most common reason for not exercising is no time. For those who are low on time, high-intensity training is a good alternative to steady-state cardiovascular exercise. People who find such high-intensity exercise uncomfortable can gain the same benefits by doing moderate-intensity exercise for a longer period of time.