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Heart rate zones defined

Coach Paul Duncan's guide to HR zones and how to use them in training and racing.


What are heart rate zones? Why do they matter? What intensity should you train at? How easy is easy enough, how hard is hard enough?

Heart Rate zones can be very confusing for athletes as every coach you ask may have a slightly different answer. Everyone has a different definition of which zones are used for which types of intensities. At the end of the day, it all means the same thing with a different label. With that said, we will use the protocol that I use for the athletes I work with.

At QT2 Systems, our heart rate training zones are set and defined after doing significant threshold testing. There are many ways an athlete can figure out their estimated threshold heart rate. We recommend collecting data from a few different tests and cross-checks before setting their heart rate zones in stone.

Once the athlete’s threshold is defined, this is how we label and define our zones:

Zone R: Recovery Zone

To set up Zone R, first create the other zones. Set up Z1 ,Z2, Z3 and then ZR last. Create a gap between the bottom of Z1 and the top of ZR. Have that gap be about 5 to 7 bpm. For example, if Z1 is 130 to 140 bpm, then ZR would be 125 and below.

Having this gap creates a “grey zone”, where no one should go, between 125 and 130. This is “no man’s land”, as it serves no purpose. This grey zone would be more like low level Z1 work rather than actual recovery.

Having no lower limits to ZR allows the athlete to go as easy as possible. There should never be any pressure to reach the top of the recovery zone.

This zone should never exceed 74% of the athletes threshold heart rate. This is an absolute maximum. “Zone R” is used for all recovery rides and runs. These workouts are crucial between key intensity sessions. Conducting these workouts correctly takes patience, but it’s very important the athlete understands how important this is. If an athlete does these workouts too hard, their peripheral system will be too fatigued to stimulate the core system during key workouts, where the goal should be pushing limits.

When it comes to recovery workouts, there is no such thing as “too slow”. We recommend staying well below the top of your recovery zone, especially during the build and speed phase of your training.

Zone 1: Aerobic endurance

Between 80 and 86% of threshold heart rate. This is the primary zone we prescribe for the bulk of our athletes’ workouts. This zone is used for almost all long rides and long runs. For most athletes, in the early season, during base building, this should be the primary zone used for all workouts. This zone is the bread and butter for an endurance athlete, the injury risk in this zone is very low, and the rewards are very high. For many athletes, this zone will feel very slow in the beginning stages, but as the athlete starts to build a solid foundation, efficiency will rise, and perceived effort in this zone will become higher.

For most athletes, if trained properly, the top of Z1 will be their Ironman distance race pace. This  will vary on many factors of course, but in general, if the athlete is trained properly, the top of Z1 is a good place to start when it comes to your pacing plan for the full distance.

 Zone 2: Endurance tempo

After the base phase, the majority of athletes should start to incorporate this zone into the end of long rides and runs. As race season becomes closer, the amount of time spent in this zone will increase. Intensity for this zone is 86% and 93% of the athlete’s threshold heart rate. For the average athlete, the top of Z2 would be a good place to start for half distance race pacing.

Zone 3: Threshold tempo

Between 93% and 100% of threshold heart rate. We use this zone to increase the percentage of pace or power at which threshold occurs relative to VO2 max pace or power. Similar to Z2, as the key races draw closer, the amount of time spent at this intensity should increase. For most athletes training for long distance events, we recommend building up to 30 minute intervals on the bike, and 20 minutes on the run at this intensity, within an aerobic (ZR/Z1) session.

Best effort repeats: (our version of Z4) 

At this intensity, we recommended not focusing on heart rate. The goal of “best effort” repeats is to increase the body’s ability to buffer and tolerate lactate acid. Best effort repeats should only be used in the final eight weeks of training before the athlete’s key race. More seasoned athletes might benefit from incorporating up to the last 12 weeks of these repeats in their schedule, but for the general athlete, eight is a safe and effective number.

These are paced to provide a best sustainable effort workout. So for example, if the prescribed workout is 4 x 1 mile best sustainable effort on the track, you should do these efforts at the best possible effort you feel you can sustain for all four repeats. See www.qt2systems.com/triathlon-calculator/ to help determine your initial training paces based on a recent 5K run time.

When best effort repeats are incorporated into your schedule, its important to slowly progress these, in both the amount of repeats conducted, and the speed at which they are conducted. The above are just some of the basics. The needs of every athlete will vary. If you need help with determining your training zones, I am available for questions. Contact me directly at paul@qt2systems.com

About the author:

Paul is a United States Army Veteran,  USAT Certified Coach, QT2 Systems Level 1 Coach, and OutRival Racing Level 3 coach.

Paul also competes in triathlon and running events in his spare time.

  • 70.3 PR (4:24:26)
    140.6 PR – (9:51:53
  • Half Marathon – (1:24:21 open)
  • Marathon – (2:57:27
To learn more about Paul, go to www.qt2systems.com/coach-paul-duncan/