Subscribe to The Adaptive Zone Podcast…
How Do I Keep My Heart Rate in Zone 2?
This is one of the most common questions I get from runners. So today I’m going to take a deeper dive into Zone 2 running. We’ll talk about what Zone 2 running is, why it’s important and how to make sure you’re doing it right so that you can improve your race performance.
What is Zone 2 Running?
Zone 2 usually refers to a running intensity that focuses on developing the aerobic system. Runners often refer to this as the “aerobic base” and training that focuses on it as “base building”.
Zone 2 running is easy; you should be able to speak clearly and in full sentences while running. It’s a running intensity that you could sustain for a long time.
Why is Zone 2 Running Important?
Build your Aerobic Base
Zone 2 Running is important because it allows you to develop your aerobic system or “build your aerobic base”. Building your aerobic base is an easy way to describe some important physiological changes that occur as a result of training in Zone 2.
For starters, zone 2 running increases the number of mitochondria in your muscle cells. Now, if you remember anything at all from high school biology, I’m sure it’s that the mitochondria are the powerhouse of the cell.
Zone 2 running also makes the mitochondria bigger. More big fat mitochondria mean you’re better able to turn the glucose and oxygen in your blood into energy. So you can run faster for the same effort. In short, it makes you more efficient.
Zone 2 running also encourages more blood vessel networks to develop in your muscles. We call those capillaries. This allows you to get more glucose and oxygen to your muscles per heartbeat. Again, making you more efficient.
Myoglobin is a little protein in your cells that transport oxygen to the mitochondria. If the mitochondria are the lead singer of the band, myoglobin is the drummer. Essentially, mitochondria get all of the attention, but if you don’t have myoglobin, the mitochondria are a bit useless.
Zone 2 running helps you develop more myoglobin and the ones you develop are also bigger. Again, this makes you more efficient at transporting oxygen, so you can run faster for the same effort.
Increase the Size of Your Aerobic Battery
The best analogy I’ve heard for this came from the guys at Runners Connect. Who described the runner as being akin to a hybrid car. The aerobic system is the electric battery and the anaerobic system is the gas tank.
When you go slow in a hybrid car, you can go on just the electric battery and you can travel really far, as long as you go slow. When you speed up, you’ll need the gas. The bigger the electric battery you have, the faster and further you can go before you need to use gas.
Ultimately, your speed on race day will be the sum of your aerobic battery and your anaerobic gas tank. You want to make both as big as possible. Zone 2 running is an awesome way to get a bigger aerobic battery.
How Do I Know What My Zone 2 Heart Rate is?
80-95% of your Lactate Threshold
Now, different people will use different zones. However, there is usually a great deal of overlap between different zone-based systems when it comes to zone 2. For my purposes, I use a 5 Zone system that puts zone 2 at 80-95% of the lactate threshold heart rate.
Now, if that makes no sense to you, I’d recommend you check out my Training Zone Calculators page. You can do the 20-minute test to determine exactly what your Zone 2 heart rate is.
However, to keep it simple today, we’ll just say that Zone 2 is 80-95% of your 1-hour max heart rate. So run for an hour and take your average heart rate. Say it was 162 bpm. Then your Zone 2 heart rate is between 130 and 153 bpm (80-95%) – this is actually my Zone 2 heart rate.
How Do I Keep My Heart Rate in Zone 2?
Now that you know what your Zone 2 heart rate is, you’re going to do 80% of your running in zone 2 in order to build your aerobic base. The problem comes when you try to run and keep your heart rate in that zone but you can’t. You run as slow as you can, let’s say 8 minutes per km (13 minutes per mile), but still, your heart rate shoots up into zone 3.
So you go to Google and type in “how do I keep my heart rate down while running”. You are presented with a few dozen videos and articles explaining how to “instantly reduce your heart rate”. However, you’re well away that if something sounds too good to be true, it probably is.
Tricks Don’t Work
The fact is that when you are running your muscles need oxygen and glucose. They get this from the blood. If you run faster, your muscles need more oxygen and glucose, so they need more blood, so your heart beats faster.
The only way to run faster for the same heart rate is for your muscles to be more efficient in using the glucose and oxygen they receive. To do this you need more capillaries, more mitochondria and more myoglobin. Or said another way, a bigger aerobic battery for your hybrid car.
In order to develop your aerobic base and build a bigger aerobic battery, you need to keep your heart rate in Zone 2. The more time you spend with your heart rate in zone 2, the stronger the signal you send to your body. Your body will create adaptations to make you more efficient at that speed. More capillaries, more mitochondria and more myoglobin. A bigger aerobic base, a bigger aerobic battery.
There are no shortcuts here. Keep your heart rate in Zone 2 at all costs. Run as slowly as you can and watch your heart rate. When it starts to creep into Zone 3, walk for 2 minutes. Then start to run again, as slowly as you can. When your heart rate creeps into Zone 3 again, walk for 2 minutes.
Remember, you can run on the spot. Meaning you can run at 0 mph. If you think you can’t run any slower, challenge yourself to try. What is the very slowest pace you can possibly run at?
How Do I Know if My Zone 2 Running is Working?
Your Zone 2 Pace Will Improve Over Time
An easy way to know if your Zone 2 heart rate training is working is to monitor your pace over time. Keep your heart rate in Zone 2 for 80% of your runs. Do that for three months and then look back at the average pace for some of the earlier runs in that time period. You should see that you can now run faster for the same heart rate.
40 Minute Test
A more formal way to do this is my 40-minute test. This is described in detail on the Training Zone Calculators page. However, it’s a pretty simple test. First up, figure out what your Zone 2 heart rate is. Mine is 130-153 bpm, so let’s use that for this example.
I’m going to warm up for 10 minutes and then increase my pace until my heart rate is hovering around 153 bpm. Then I’ll start my watch and run at a pace that holds my heart rate around 153 bpm. I’ll maintain this heart rate for the whole 40 minutes.
My average heart rate during that 40 minutes should be 153 bpm. I can then look to see what my average pace was. Let’s say it was 07:39 min/km. I’ll write that down somewhere and then put in my schedule to repeat the test every 4 weeks.
If I continue to train in zone 2 for the majority of my runs, I should expect to see my average pace at 153 bpm improve. So my average pace for the 40-minute test would gradually increase but my heart rate would stay the same.
The results might look something like this:
- March 6: 07:39 min/km (153bpm)
- April 3: 07:30 min/km (153bpm)
- May 1: 07:25 min/km (153bpm)
- May 29: 07:15 min/km (153bpm)
- June 26: 07:08 min/km (153bpm)
How Long Does it Take for Zone 2 Training to Work?
It takes a long time to build your aerobic base. I always tell my athletes to think months and years, not days and weeks. The good news is that it also takes a long time to lose it. So if you build up a massive aerobic battery, you could stop running for a couple of months without losing too much of that fitness.
I usually schedule 40-minute tests every 8 weeks for my clients. This is usually long enough to see some improvement. However, I suggest you take a long-term view here. Schedule a 40-minute test every 6 months and plan to do it for years and years.
Does Zone 2 Training Make you Faster?
The short answer is yes. How fast you can run on race day is essentially the sum of your aerobic battery and your anaerobic gas tank. You can, and should, try and make both of them as big as possible. Zone 2 heart rate training is an excellent way to increase the size and power of your aerobic battery.
- 00:00 Introduction
- 00:55 What is Zone 2 running?
- 01:11 Why is Zone 2 running important?
- 05:15 How do I know what my Zone 2 heart rate is?
- 06:41 How do I keep my heart rate in Zone 2?
- 11:06 How do I know if my Zone 2 running is working?
- 14:42 How long does it take for Zone 2 training to work?
- 15:11 Does Zone 2 training make you faster?
More from Matthew Boyd Physio
- Free Online Course: Running Fundamentals
- Subscribe to The Adaptive Zone Podcast
- Subscribe to The Adaptive Zone YouTube Channel
- Facebook @matthewboydphysio
- Instagram @matthewboydphysio