Heart Rate Zones for Endurance Training

Training by heart rate zones is an invaluable tool for endurance athletes. Understanding heart rate zones and using the appropriate application in a training program is a major piece of the puzzle when working to optimize performance and maximize training efficiency. Knowing your heart rate zones allows you to tailor your training to specific intensities and ensure that you are not over or under loading an individual workout. In this article, we’ll dive into the concept of training zones, the purpose of training in each zone, the different methods used to calculate training zones and an overview of how to use your heart rate zones in training. 

Understanding Heart Rate Zones:

Heart rate zones are specific ranges of beats per minute (BPM) that correspond to different exercise intensities. Each zone elicits a different physiological response in the body, and each zone serves a unique purpose in endurance training. While you will see different variations and numbers of zones, the most common is a 5 zone split. 

The basics of each of those zones is as follows:

Zone 1 - Easy / Recovery:

• Zone 1 represents very light intensity training. 

• This zone should be used for warm-ups, cool-downs and recovery workouts. 

• Zone 1 training can improve overall cardiovascular health and aid in active recovery between harder training sessions.

Zone 2 - Aerobic Base:

• Zone 2 is the zone where the majority of endurance training should take place. It helps to develop aerobic capacity without overloading the cardiovascular system. 

• Training in this zone improves endurance and enhances the body’s ability to burn fat as a fuel source. 

• Workouts in this zone should be “conversational”. The pace should be comfortable and sustainable for longer durations. 

Zone 3 - Aerobic Endurance / Tempo:

• Zone 3 is your “temp zone”. This is where you start to push a bit harder. Training in this zone can increase your lactate threshold, improve running economy, and enhance your body’s ability to clear lactate from muscles. 

• Training in this zone too often can cause more harm than good if you do not allow your body adequate recovery time between harder workouts. 

• Workouts in this zone should feel moderately hard, but breathing should still be controlled and the pace should still be maintainable for an extended period.

Zone 4 - Threshold:

• Training at threshold can push your lactate threshold, referring to the point where the body accumulates lactate faster than it can clear it. Workouts in this zone can improve your ability to sustain higher intensity efforts for longer periods of time, enhance your endurance and boost overall race-effort performance. 

• These workouts should be used with caution. Training at threshold too often without enough recovery can easily push you from “functional overreaching” to “non-functional overreaching” and then into “overtraining”.  

• Threshold training is generally done in medium-duration intervals, as it is hard to maintain for extended periods. 

• These workouts should be challenging, and threshold pace will no longer be a conversational pace. 

Zone 5 - Max Effort, VO2max training:

• Zone 5 is maximum effort. This training is done in short, intense intervals. Training in this zone improved anaerobic capacity, speed and power. These workouts should push your limits for short durations. 

• Training in zone 5 should be used sparingly for the endurance athlete, and especially for those newer to the sport. While training in this zone and using hard intervals can come with true benefits of improved speed, strength, form and power, the risks often can outweigh the benefits.

• It is also less sport and event specific, as you will not be racing in an anaerobic state for any endurance event. 

Methods of Heart Rate Calculation Include:

Maximum Heart Rate Formula:

This is the most commonly used method for calculating heart rate zones. This is based on estimated maximizing heart rate (MHR), using the formula “220 - age” and then zones created based on a certain percentage of MHR. While this method is straightforward and easy to use, it provides a rough estimate and does not account for individual variations. 

Zones are frequently broken down into the following ranges: Z1= 50-60% MHR, Z1= 60-70% MHR, Z3 = 70-80% MHR, Z4 = 80-90% MHR, Z5 = 90-100% MHR. While these zones are arguably the most commonly used, they are not necessarily accurate to your true aerobic, threshold and anaerobic zones. Zone 4 and Zone 5 are typically a smaller range than zone 1 and zone 2, but this calculation does not account for that. See below for more information on individual variations in training zones.

This method is a fine place to start until you can figure out your individual zones. However, if you are using a Garmin device, I would probably recommend going off of Garmin’s calculated zones before using the max heart rate method described here.

Maximum Heart Rate Testing:

Calculations are the same as above, but with your individual maximum heart rate accounted for. See below for more information on MHR testing.

Heart Rate Reserve (HRR) Calculation:

Heart rate reserve calculations take into account both your resting heart rate (RHR) and your maximum heart rate (MHR). HRR represents the “cushion” heartbeats per minute for exercise. The formula to calculate your HRR is HRR = MHR - RHR. 

To calculate your specific zones, take your specific % range, multiple that % by your HRR and then add your resting heart rate back in. Zone calculations may fall within the following ranges:  Z1 = (50-60% x HRR) + RHR, Z2 = (60-70% x HRR) + RHR, Z3 = (70-80% x HRR) + RHR, Z4 = (80-90% x HRR) + RHR, Z5 =  (90-100% x HRR) + RHR.

As above, in reality, heart rate zones do not have an equal 10% range split. See below for more information on these variations. 

This method allows for individual variation in resting heart rate and can provide a more accurate training zone calculation. However, note the training zones are always higher when using HRR calculations as compared to simply using MHR.

Exercise Testing Methods:

Maximal Exercise Testing:

This is simply a more accurate way to find your individual maximum heart rate to then get more accurate training zones. Testing can be done “lab-based” or “field-based”. 

In lab based maximum exercise testing, you are monitored by a professional while performing progressively intense bouts of exercise until you reach your maximum heart rate. Lab-based testing is currently the gold standard to MHR measurements, but it is not always accessible. 

Field based max heart rate testing is simply testing your maximum heart rate on your own. You can choose to do as intense bouts of exercise as possible (such as hill sprints) after an appropriate warm up. Other field tests can estimate your threshold zone using various methods and formulas such as a 30 minute best effort, 60 minute run test, 12 minute run test, etc.

Lactate Threshold Testing and VO2 max testing:

These tests are also conducted in a lab setting. They are not commonly used by amateur athletes due to inaccessibility. However, many large medical systems or sports performance facilities have this type of testing available. Testing for both lactate threshold and Vo2 max both involve increasingly intense exercise bouts on a bike or treadmill in a lab.

VO2 max testing is a maximal exercise test performed while connected to a mask that analyzes expired air. This provides data on how much oxygen you use while exercising and how much oxygen you can consume while exercising. This testing is considered the gold standard measurement for endurance testing.

Lactate threshold testing involved measuring blood lactate levels at various exercise intensities. This provides data on the point where your body begins to accumulate lactate faster than it can clear it. With this information, heart rate zones can be calculated based on lactate threshold.

Variations in individual training zones:

Are you now wondering why there isn’t a clear-cut percentage formula of max HR or HRR to determine specific heart rate training zones? The easy answer is that everyone is just a little bit different. For perspective, according to research from the University of Virginia School of Medicine:

• The average person reaches their lactate threshold at about 50-60% of their VO2 max

• Recreational / amateur athletes reach their lactate threshold at 65-80% of their VO2 max

• Elite endurance athletes reach their lactate threshold at 85-95% of their VO2 max

How do I use this information in my training?

A good training plan will include different workouts that target various energy systems leading to specific adaptations, largely by using training zones to know you are working the correct system. So, use the above information to determine the best method for you to determine your max heart rate and appropriate training zones, or simply use the zones that are suggested by your Garmin device. Utilize a heart rate monitor during your workouts to ensure that you are training in the desired zone. 

Keep in mind that during a build phase, you will likely want your training time to be close to 80% zones 1 or 2 and 20% zones 3-5. This is an evidence based approach to optimize your training while allowing for adequate recovery between harder sessions. Of course, your specific intensity ratio will vary based on your experience level and the event distance for which you are training.

Of course, also make sure you are paying attention to your rate of perceived exertion. While heart rate zones provide an invaluable framework, you also need to listen to your body and adjust intensity levels accordingly. Keep in mind that factors such as fatigue, stress, and environmental conditions can all influence heart rate responses.

Aside from knowing you are training in an appropriate heart rate zone, monitoring your heart rate has other benefits as well. Unusual changes in resting heart rate or heart rate response to exercise can be an indicator of illness, excessive stress or loading, or overtraining syndrome. 

Conclusion:

Heart rate zones are a great tool for providing a structured approach to endurance training, enabling you to train smarter and achieve better results. Understanding the different heart rate zones and how they relate to specific physiological adaptations is essential to designing a safe and effective training program tailored to your individual goals. 

Did you enjoy this article? Is there anything else you would like to see us write about? If so, drop us a message in the contact form!