Heart rate training can be confusing due to the many different types of the terminology used and the many opinions on how we determine what our threshold zone is. Additionally, there are many different charts that give us a variety of ranges which adds to the confusion. This is an example of information overload, and to a beginner triathlete, this can seem incredibly confusing. My goal for this article is that you have a good understanding of how and why to test for heart rate zones, which training zones you should spend the most time in, and to make this a simple process.

We’ll start with the definition of Training Zones:

A definition of Zone 1 is that it’s a super easy effort, probably a 4/10 on the Rate of Perceived Exertion (RPE), see chart at the end. It’s so easy that you should feel “guilty” when you are done. You don’t think you went hard enough; it didn’t feel like a workout; you don’t think there was any benefit because it felt too easy, etc. If you have these types of thoughts after a Zone 1 workout, then congratulations, you are doing it right!

I call this the “Guilty Zone.”

A definition of Zone 2 is a bit more complicated, as it should feel pretty easy, at least in the beginning. But you should feel as though you have to work if you’ve been doing this for several hours. You may even see a cardiac drift towards the end of this workout. How easy is easy for Zone 2? I would recommend somewhere around 5-6/10 on the RPE scale. You should be able to hold a conversation for the duration of this workout, and I mean being able to talk in full sentences, not 1 or 2-word gasps.

This is what I call the “Conversation Zone.”

Zone 3 gets a little gray, and literally, it is a ‘gray zone’. You typically aren’t going easy enough to get the benefits of a nice easy effort and you aren’t going hard enough to get the benefits of a ‘Race Pace’ type workout. This is an effort of about 7/10 on the RPE scale, and you can talk in one to two-word answers.

I actually call this zone the NBZ “No Benefit Zone.”

Zone 4 is your “Race Pace” zone, this is where you have burning legs and lungs and you can’t keep the effort up for much more than an hour. And yes, you have to be pretty fit to keep this effort up for an hour, but by definition, your threshold is an effort you can manage for one hour. You know when you are in Zone 4 as your breathing is labored, your arms and legs get very heavy and all you want to do is stop. This effort is 8-9+ on the RPE scale.

Zone 5 and up are for shorter efforts and these are usually 9+ to 10 types of efforts on the RPE scale. These efforts may last from a few seconds to maybe five or six minutes. This zone is beneficial if you are doing a lot of racing that has hard but very short efforts, such as bike racing or racing short events on the track in running.

Since this article is geared toward endurance athletes and our races our typically one hour or more, let’s understand how our training should be set up. Consider that a 400m race around the track that takes world-class runners about 40 seconds to complete is around 86% aerobic. Now, if you are running a 5k, how much of that race do you think is aerobic? The answer is probably somewhere around 97-99%. For the average athlete the percentage of zone training for each zone should be roughly:

80-85% Zone 1 and Zone 2
10-15% Zone 4
2-5% of Zone 5
(For those of us who are training for half ironman distances and above there should be a percentage of Zone 3 training as well, but still that percentage may only be 15-20% a week.)

The importance of Zone 1 and Zone 2 Training

Zone 1 and 2 training is important because of the benefits of these workouts. You build endurance, durability, and strength. In addition, these easy training sessions help build capillary pathways that transport oxygen to your muscles and carry waste (lactate) away from your muscles. The more capillary pathways that you can build, the more efficient you will be. Efficiency is equal to free speed.

If at first, you can’t keep your HR under Zone 2, then you need to slow down. If that means you run for 3 minutes and walk for 2 minutes to keep your HR down then by all means do it. For a fit athlete getting back into training, I recommend not training with the heart rate monitor for 2 weeks and then putting it on once you have a sense of fitness coming back. You may find that training in Zone 2 and under is a step back, but you will see the progress over time and will be thankful you were patient enough to try this.

Adaptation for everyone will be different. Some people will see changes right away, and for others, it may take months. Just this year I had an athlete drop about 40 seconds a mile on his long runs after 2 months of Zone 2 training, and he’s been racing and training for over 20 years! So, at any level improvement is possible, but you need to have faith in the philosophy and above all else, be patient.

Determining your zones

Determining training zones is a simple process and I’ve written quite a bit on this before. If you are an experienced athlete you can use this method.

RPE Scale

RPE Zone HR Zone Description
0 Z1 Complete Rest
1 Z1 Very easy; light walking
2 Z1 Very easy; light walking
3 Z1 Very easy; walking
4 Z1 Still easy, maybe starting to sweat
5 Z2 Starting to work just a little and you can feel your HR rise
6 Z2 Upper Working but sustainable, able to talk in full sentences
7 Z3 Strong effort; breathing laboured, but can still maintain pace for some minutes without slowing.
8 Z4 Olympic Distance Race Pace for MOP to FOP
9 Z5 10k effort, very hard
10 Z5+ Z5+ = 5k effort and Z5++ = cannot hold effort for more than a minute or two. (almost maximal effort)

In conclusion, it’s my hope you’ll follow the methods here in your training and see what great improvements training in Zone 1 and 2 will bring you.

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