Triathlon Heart Rate Training Zones Calculator

By "Triathlon" Taren Gesell and Julia Żuławińska
Last updated: Aug 04, 2021

Learning how to use heart rate to dictate your training is a crucial ability for beginner triathletes to develop. To help you, we created this triathlon heart rate training zones calculator.

How much time should be spent in low-intensity vs. high-intensity training zones? Should you use heart rate for all training zones? What are the downsides to using heart rate to dictate your training? How do you adjust heart rate training based on how your body changes throughout the year?

These are all excellent questions commonly asked by triathletes, and we’ll answer them all for you here in this post.

Why use heart rate for endurance training?

Physiologically, there are three “zones” that our body experiences:

  • Under Lactate Threshold #1 (LT1) — Low-intensity training zone comprised of Zones 1 and 2 in our five-zone training model. This training zone builds up the mitochondrial density in your muscles, increasing the amount of energy you can produce.

  • Between Lactate Threshold #1 and Lactate Threshold #2 (LT2) — Moderate-intensity training zone comprised of Zone 3 and the bottom half of Zone 4. This is commonly known as Sweet Spot training and builds more mitochondria than low-intensity training. Still, it’s quite stressful on the body because, at this intensity, your body is producing more lactic acid than it can clear. So after the workout, you have a much higher stress response in your body than when training under LT1.

  • Above Lactate Threshold #2 — High-intensity training comprised of the top of Zone 4 and Zone 5 in our five-zone training model. Blood lactate levels at this intensity are extremely high. This high-intensity training improves the function of the mitochondria you have so that each muscle fiber can produce more energy. While this intensity is very hard on the body, it’s so hard that most athletes can’t perform much at this intestinal level before stopping; it’s self-limiting.

Many studies have confirmed that total training hours don’t dictate how well triathletes perform in their races. Instead, having trained with a proper distribution of time spent in each training zone is a very key predictor of race performance and the overall longevity of an athlete. So it is critical to know where your training zones are and how much time to spend in each zone.

We use heart rate training because it’s an excellent approximation athletes can use to determine their lactate training zones.

The calculator we’ve created for you here is based on the Karvonen formula, which uses your unique maximum heart rate and resting heart rate. In my experience, it’s much more accurate than heart rate training formulas that arbitrarily use your age or some measures of wellness. Instead, the Karvonen formula produces training zones that are unique to you.

How to triathlon train using heart rate?

  • Training Zone 1 — Very low-intensity training zone that should comprise roughly 30-40% of your total annual training hours. Swimming and long, low-intensity rides will mostly be in this zone, but it will be difficult to run at such a low-intensity level.

  • Training Zone 2 — Low but steady training zone that will comprise roughly 40-50% of your total annual training hours. Some swimming and endurance-focused riding will be in this zone. Athletes should work to run a lot in this zone, but they’ll likely have a hard time doing so when they start.

One thing to know about this training zone is that even though it may be hard to keep your heart rate under the top of this zone's threshold, it’s essential to do so. If you’re sick, if it’s too hot, if you’re on hills, if you just traveled, or if you had alcohol the night before, you’ll likely drive your heart rate up. In all cases, you should still treat your heart rate cap as a hard and fast ceiling that you don’t want to go over; even though your pace will be slower, you’ll still be in the right training zone to create the right physiological adaptations.

This training zone is where athletes have the largest number of questions. Have a listen to my (Taren's) podcast, where I answer the most commonly asked questions.

🏃🏽 The top of this zone and the bottom of Zone 3 is where most athletes will race an Ironman triathlon.
  • Training Zone 3 — Should comprise roughly 10-15% of your total annual training hours. It is often where athletes will race a half-Ironman triathlon, and there should be some training in this zone leading up to the race to familiarize yourself with the effort.

  • Training Zone 4 — Fairly intense training zone where the low end is called sweet spot training, and the high end is called threshold training. It should comprise 5-10% of your total annual training time.

🏃🏽 Training zone 4 is where a lot of athletes will race an Olympic distance triathlon.
  • Training Zone 5 — Very intense training zone where you’ll spend 5-10% of your total annual training time. This is where most athletes will race a sprint triathlon.

At this intensity level, I don’t actually recommend using heart rate. Intervals at this intensity level are often so short that your heart rate won’t actually get up into this zone until the very end of the interval; so instead, choose to use rate of perceived exertion of 9-10/10 for these intervals and look at your heart rate after the workout is over.

To learn how often and what to eat during your triathlon training and races, go to our triathlon nutrition calculator.

"Triathlon" Taren Gesell and Julia Żuławińska
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