What are heart rate zones? How does it help determine exercise intensity?

Each heart rate zone offers specific benefits, such as improved cardiovascular fitness, increased endurance, and enhanced fat loss.

BySumit Jha

Published May 07, 2024 | 7:00 AM Updated May 07, 2024 | 7:00 AM

What are heart rate zones? How does it help determine exercise intensity?

In the realm of short-form videos across various social media platforms, fitness content stands out as one of the most-watched genres.

In this genre, the phrase “heart rate zones” has become ubiquitous. With the advancement of technology, wearable devices that monitor heart rate zones have emerged as supplements to exercise.

Heart rate zones serve as a method for categorising the intensity of exercise based on the heart rate. These zones are typically divided into several ranges corresponding to a percentage of the maximum heart rate.

Each zone offers specific benefits, such as improved cardiovascular fitness, increased endurance, and enhanced fat loss. Understanding and training within these zones can help individuals optimise their workouts and recovery, leading to better overall fitness and performance.

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The zones

There are typically five heart rate zones

Zone 1 (Very Light): This zone corresponds to 50-60 percent of the maximum heart rate (MHR). It’s ideal for recovery, warm-up, and low-intensity activities such as walking or easy bike rides. Zone 1 helps enhance overall cardiovascular fitness and endurance.

Zone 2 (Light): Around 60-70 percent of the MHR, this zone is suitable for base-level aerobic activities. It aids in improving cardiovascular fitness, endurance, and fat loss.

Zone 3 (Vigorous): This is 70-80 percent of your MHR, this zone is considered moderate in intensity. It benefits cardiovascular fitness, enhances blood circulation to muscles and the heart, and improves endurance.

Zone 4 (High): Occupying 80-90 percent of your MHR, this zone is intense and aids in improving anaerobic capacity, speed endurance, and cardiovascular fitness. It’s particularly beneficial for athletes training for high-intensity activities.

Zone 5 (Maximal): In the range of 90-100 percent of your MHR, this zone is the most intense. It’s typically used for short bursts of high-intensity exercise. It’s important to note that Zone 5 is not recommended for individuals who are not well-trained athletes due to the risk of adverse effects like dizziness, fainting, and increased blood pressure.

“Monitoring heart rate and training in the appropriate zones can help one achieve specific fitness goals — whether that’s improving endurance, speed, or fat loss. A fitness tracker or heart rate monitor can be used to track your heart rate zones during exercise,” said Hyderabad-based cardiologist Dr Mukherjee Madivada.

He added that the zones were based on a person’s lactate threshold, which describes the point at which exercise intensity moves from being predominantly aerobic to predominantly anaerobic.

Aerobic exercise uses oxygen to help the muscles keep going, ensuring people can continue exercising for a long time without fatiguing. Anaerobic exercise, however, uses stored energy to fuel exercise.

Anaerobic exercise also accrues metabolic byproducts (such as lactate) that increase fatigue, meaning we can only produce energy anaerobically for a short time.

On average your lactate threshold tends to sit around 85 per cent of your maximum heart rate, although this varies from person to person, and can be higher in athletes.

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How to calculate Heart Rate Zones?

The way to calculate heart rate zones using the Karvonen method is:

1. Determine Your MHR: Utilise the formula MHR = 220 – Age to estimate your maximum heart rate. For example, if you’re 40 years old, your estimated MHR would be 180 beats per minute (bpm).

2. Calculate Your Heart Rate Reserve (HRR): Subtract your Resting Heart Rate (RHR) from your MHR. For instance, if your RHR is 40 bpm, your HRR would be 180 bpm – 40 bpm = 140 bpm.

3. Calculate Your Heart Rate Training Zones: By applying percentages of your HRR, you can establish your heart rate zones. Typically, there are five zones:

  • Zone 1: 50-60 percent of HRR + RHR
  • Zone 2: 60-70 percent of HRR + RHR
  • Zone 3: 70-80 percent of HRR + RHR
  • Zone 4: 80-90 percent of HRR + RHR
  • Zone 5: 90-100 percent of HRR + RHR

4. Example Calculation: If your HRR is 140 bpm and you aim to find Zone 2 (60-70 percent intensity), you’d compute 140 x 0.6 = 84 bpm and 140 x 0.7 = 98 bpm.

Adding your RHR of 40 bpm, your Zone 2 target heart rate range would be approximately 124-138 bpm.

It’s important to note that while these calculations offer general guidelines, individual fitness levels and goals may necessitate adjustments. For personalised guidance, it’s advisable to consult a fitness professional or a medical practitioner to determine the most suitable heart rate zones for your training regimen.

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Benefits of training in correct zones

Hyderabad-based Ravi Ravinder pointed out the benefits of training in different heart rate zones which offers numerous benefits for athletes and individuals striving to enhance their fitness and performance. Here are some key advantages:

1. Improved Cardiac Output: Training across various heart rate zones enhances cardiac output by boosting the heart’s efficiency in pumping blood, thereby enhancing overall cardiovascular fitness.

2. Increased VO2 max: Targeting specific heart rate zones enables athletes to elevate their VO2 max, indicating the body’s maximum oxygen utilisation during exercise, which is crucial for cardiovascular fitness and endurance.

3. Boosted athletic performance: Tailoring training to individual heart rate zones optimises workouts and recovery, enhancing athletic performance by aligning efforts with specific fitness objectives such as endurance, speed, or fat loss.

4. Optimised workouts and recovery: Heart rate training enables precise control over workout intensity and recovery, ensuring workouts suit individual fitness levels and goals, mitigating the risk of overtraining or undertraining.

5. Improved endurance: Training across diverse heart rate zones gradually increases exercise duration before fatigue, strengthening heart and lung muscles for more efficient blood circulation and enhanced endurance.

6. Enhanced recovery: Heart rate training aids in determining appropriate activity levels for fitness and conditioning, facilitating adjustments for optimal recovery and progress toward fitness goals.

7. Measuring progress: Heart rate training provides a measurable metric to track fitness progress over time, aiding in gauging improvements and adjusting workouts accordingly.

8. Weight loss and fat loss: Heart rate training, particularly for the general population, is effective for weight and fat loss, alongside improving overall fitness and reducing triglyceride levels.

9. Improved mood and reduced pain: Exercise, including heart rate training, has demonstrated benefits in mood regulation and pain reduction, contributing to overall well-being.

10. Efficient training: Heart rate training offers a structured approach to exercise, ensuring efficiency and effectiveness by targeting specific fitness and performance aspects across various heart rate zones.

(Edited by Arkadev Ghoshal)