You’re Not Really Training in Zone 2 (You Just Think You Are)

Zone 2 training sessions - long, slow workouts - are increasingly popular amongst endurance athletes. However, aiming for a Zone 2 workout and actually doing one successfully are two different things, as Matt Fitzgerald explains.

Zone 2 training is the new high-intensity interval training (HIIT). Everyone today is hyping the benefits of long, slow workouts, which is quite a change from a decade ago when everyone was hyping the benefits of short, fast workouts.

Except for me. My book 80/20 Running came out a decade ago. In it, as you may know, I hyped the benefits of long, slow workouts, not because it was trendy to do so but because it wasn’t. Having known since high school that time spent in Zone 2 is the key to unlocking endurance fitness (although we didn’t call it Zone 2 back then), I wrote 80/20 Running to save athletes from the “go hard or go home” mentality that predominated in 2014.

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I’d like to say mission accomplished, but it isn’t. A lot has changed in the last ten years—that I don’t deny. Athletes know all about Zone 2 and are buying into the 80/20 rule of intensity balance. The notion of going slower to get faster made no sense to anyone when I started preaching this message, and thankfully that’s no longer the case. But is the average Joe or Jane actually training the way the elites have for forty years, which is to say, doing at least 80 percent of their weekly training in Zone 2? Not even close.

Studies show how little Zone 2 training we do

For proof, look no further than a 2021 study led by João Henrique Falk Neto and published in the journal Sports. Nine recreational triathletes kept detailed training logs during the final six weeks before an Olympic-distance triathlon and for two weeks afterward. On average, the subjects were found to have completed just 47 percent of their combined swimming, cycling, and running at low intensity, and in only two weeks of the eight weeks for which data was collected did they spend more than half of their training time at low intensity.

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The important thing to note about this study is how recently it was done—just a few short years ago when Zone 2 training was almost as cool as it is today. We can assume therefore that a lot of the athletes included in the study fully intended to do 80 percent of their training in Zone 2 yet fell short. If this is true, then merely intending to adhere to an 80/20 intensity balance does not guarantee actual 80/20 training.

Avoiding common pitfalls

Why not? The in-person coaching I do at Dream Run Camp has taught me that people make all kinds of excuses for noncompliance with Zone 2 training. One runner told me that he hadn’t felt like he was pushing himself in a so-called easy run in which he’d been above Zone 2 almost the entire time. That’s nice, but it’s also irrelevant. It’s the physiology that matters, not the feeling. If your heart rate is above 80 percent of maximum, give or take, then you are above Zone 2, regardless of how you feel. And if you’re above Zone 2, you’re not getting the full benefits of Zone 2 training.

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Another Dream Runner congratulated himself for averaging 9:58 per mile in an easy run in which I’d told him to keep his pace below 10:00 per mile, calling it a rounding error away from perfect. There are two problems with this particular rationalization. The first is that a little above Zone 2 is still above Zone 2. You don’t get any points for not being way above Zone 2. But the bigger problem is that the body does not experience averages; it experiences actual time spent at certain intensities. The only way to get an average pace for a run slightly above the upper limit of Zone 2 is to spend a significant amount of time within the run above Zone 2.

Avoiding these common pitfalls takes discipline. You need to make a firm commitment to fulfill your intention of training in Zone 2 and make no excuses. If you train by heart rate, keep your beats per minute below 80 percent of maximum from the start to the finish of every training session targeting Zone 2, even if this requires you to walk up steeper hills. If you train by pace, keep your pace below 65 percent of your maximal aerobic speed (which is the fastest pace you could sustain for 6 minutes) at all times in easy runs.

Everyone’s talking about Zone 2 training lately, but few are doing it correctly. This creates an advantage for those who give more than lip service to the method. The hype is valid—heeding the 80/20 rule of intensity balance will give you better results than any alternative. But it only works if you actually do it!