Does Zone 2 Running Really Work?
For years, I considered Zone 2 training a complete waste of time. I thought it was a classic case of the fitness industry overhyping the latest trend.
Each time I tried it, after being convinced by another YouTube video, I’d head out the door and start running, only to find my heart rate drifting up into the 160s after about 10 minutes.
I’d get so frustrated. I’d run at what felt like a snail’s pace, and still, my heart rate would gradually creep up into Zone 3.
Was it that my watch was measuring my heart rate inaccurately? Was it that I’d calculated my heart rate zones wrong? Or was it that I simply had no aerobic fitness?
I tried using a chest strap heart rate monitor. No difference. That ruled out the watch.
I researched different ways to calculate heart rate zones. I found and used the Karvonen method, which indicated my heart rate zones were higher than I previously thought. It helped, but I was still running in Zone 3.
Rather than admitting to myself that I had no aerobic base (which was probably the case, given that most of my 12 years of training have been in the gym), I convinced myself Zone 2 running was a complete waste of time, and I stopped monitoring my heart rate entirely.
Big mistake.
How Not To Train
I’ve always wanted to train as hard as possible, which was very helpful in my years of strength and bodybuilding training, but it’s a disastrous way to approach endurance training.
A quote I’ve since heard that I love that sums this up perfectly is:
Running is one of the hardest sports in the world. It’s the only sport where doing more is likely to lead to worse outcomes.
(I can’t remember the exact source, but I think it came from Stephen Scullion, Olympic marathoner — @stephenscullion262 on YouTube.)
I ran my first ever half marathon last year. I followed a 12-week, 4-day-a-week training plan which consisted of:
- One 30–45 minute easy run
- One tempo run, at race pace or just under
- One interval run at around my 5km pace
- And one long run, which often involved stretches as race pace
It was a plan that very much followed my ‘more is better’ training philosophy. It was more 20/80 training than the 80/20 recommended by most coaches.
I knew I’d made a mistake about 3 weeks in when I started to see signs of shin splints. But I just had to push through and keep training hard.
Of course, my shin splints gradually worsened. At one point in the 12-week period, it was a struggle to even walk. And eventually, on the last run before the race, I suffered a stress fracture.
I still managed to complete the race in my goal time, but after that race I had to take 6 weeks off running completely, and then I spent a further 6 weeks gradually building up mileage again.
I Finally Tried Zone 2 Training
That stress fracture was the final straw. I was sick of the constant injuries. I just wanted to be able to run consistently.
The injury meant that I had to run slower and gradually build back into training. 6-minute kilometres went from being thought of as pathetic to the usual pace of my easy runs.
I finally started training in Zone 2, and my fitness exploded.
I went from the majority of my training being hard to the majority being easy—a true 80/20 split.
I was determined to stay injury-free and train the right way.
I wrote my own training programme, centred on Zone 2 running. It included three easy, aerobic runs per week of 30–60 minutes, one hard interval or tempo workout, and one long run that was half easy, half race pace. It amounted to 150–210 minutes of Zone 2 training per week. Mileage peaked at around 55km.
I trained by heart rate, and I was very strict with myself about keeping my easy runs within Zone 2 (which, based on the Karvonen formula, is between 142 and 155 bpm for me).
If I felt like my heart rate was getting out of control, I’d stop and wait for it to drop to the bottom of Zone 2, then start again at a slower pace. And I’d set pace alerts on my Coros watch so that it would make noises at me if I started running too fast.
The first four weeks were tough. I didn’t feel like I was making much progress. There were some days when I had to run way slower than I’d ever had to stay in Zone 2 (around 6:15/km). And I really struggled to stay in Zone 2 for more than about 6–7km at a stretch.
During week 4, I ran a 5km effort to see if it was working, and I saw a 15-second improvement without running a true max effort. Promising.
The second 4 weeks were much easier. I reached the point where I could comfortably hold a 5:45/km pace, and I even managed to stay in Zone 2 for the entire duration of a 16km long run.
Here’s a comparison between two easy runs 8 weeks apart, running the same route:
You can see that my average heart rate reduced by 10 bpm while I was able to hold a slightly faster average pace. I had to slow down a lot towards the end on the first run, whereas on the second, I was able to speed up.
At the end of the eight weeks, I performed another 5km effort. This time, I completed it in 20:35! And I still had gas in the tank — I ran the final km in 3:50/km.
Most importantly, though, I saw no signs of injury and barely noticed a niggle. Even though my weekly mileage was higher than ever. It was a complete contrast from all the running I’d done in the past.
I was amazed. I went from Zone 2 sceptic to Zone 2 believer. Zone 2 training has remained a big part of my training since and will continue to do so as I chase down a sub-3hr marathon and qualify for Boston.
Were my results typical?
It took 4–5 weeks before I started to notice significant improvements.As this was the first time I’d ever focused on Zone 2 training, I expected my rate of progress to be higher than typical — it was beginner gains. The research says it takes 4–8 weeks to start to see results from this training style.
The amount of progress you’ll see is also dose-dependent. Andrew Huberman recommends 150–180 minutes per week of Zone 2 cardio to achieve maximum benefit.
Not everyone has time for that, but for beginners or those with limited time, even half an hour twice per week should be enough to notice improvements.
My Tips for Zone 2 Training
Here’s what I learned in my Zone 2 experiment:
- Start out running slower than you think. It’s very easy to accidentally push your heart rate into Zone 3 or 4. I made this mistake a lot. It can ruin your whole workout. Studies show it can take 20–30 minutes for your body to become aerobic again after pushing into the glycolytic or anaerobic zones. Start slower than you think, you can always speed up later in the run.
- Improvements in aerobic fitness are primarily driven by volume. The key to improving your aerobic Zone 2 capacity is spending a lot of time in that zone. As you do so, your body becomes more aerobically efficient. Aim to gradually increase the amount of time you’re spending in Zone 2 each week.
- Do more sessions but for less time. In my first 2 weeks of Zone 2 training, I originally programmed two longer workouts, but I found that I kept drifting into Zone 3 after around 35–45 minutes, even if I dropped my pace. I instead split the two sessions into three and moved from a 4-day to a 5-day-per-week plan. This allowed me to easily increase my Zone 2 training volume.
- Combine Zone 2 training and high-intensity training into one session. This is another easy way to sneak in more Zone 2 training time. You can perform both Zone 2 training and Zone 4 or 5 training in one session. But make sure you do Zone 2 first, given what I mentioned in tip #1. Either extend your warm-ups on your interval/tempo runs or run the first half of your long runs at an easy pace.
- Don’t be afraid to rest. Zone 2 training is all about controlling your heart rate. If your heart rate starts to get out of control, rest or back off until it drops to the bottom of your Zone 2 before starting again. Pace doesn’t matter, time spent in Zone 2 does.
- Stick with it. It may feel impossible to stay in Zone 2 now, but it will pay off in a couple of months’ time. Trust the process. It will work.
Zone 2 Training Will Pay Off
I bailed on most of my attempts at Zone 2 training before an injury finally forced me to slow down.
As much as I was frustrated at the time, that stress fracture may have been the best thing that could have happened to me for my long-term fitness.
Trust the process and stick with it. It will be frustrating and tough at the beginning, but in the end, you’ll be very glad you stuck with it.
I hope you like this article! If so, there are plenty more on my blog.
I’m new to the blogging and writing business, so your feedback or thoughts are welcome. Thank you for reading!
