Zone 2 Running: The Science, Benefits & How to Do It
- 3 days ago
- 21 min read
A deep dive into the science, the strategy, and one runner's story that proves the power of easy miles
By Andy Hood — ultra and endurance runner, cancer survivor, men's wellness advocate, and Runna ambassador. Running the trails and coastlines of North Devon and beyond. runningwestwardho.co.uk
There is a quiet revolution happening in running, and it goes against almost every instinct that new and experienced runners share. The idea is simple, and slightly counterintuitive: to become a better runner, you need to slow down. Not a little. A lot.
For most recreational runners, that means running at a pace that feels almost embarrassingly easy, a pace that might even prompt passing walkers to do a double-take.
This is Zone 2 running. And it might be the single most important shift any runner can make.
Table of Contents
What Is Zone 2?
Heart rate training divides your cardiovascular effort into five zones, from gentle recovery walking at Zone 1, all the way to maximum sprint effort at Zone 5. Zone 2 sits at the lower end of this spectrum, generally defined as 60 to 70% of your maximum heart rate. In practical terms, this is a pace where you could hold a full, comfortable conversation without gasping for breath, speak in complete sentences, and feel like you could genuinely keep going for a very long time.
For most endurance athletes, Zone 2 represents an "all-day" effort, a pace sustainable for long periods without burning out. It targets your aerobic energy system almost exclusively, meaning your body is primarily using oxygen to generate fuel rather than tapping into the faster but more costly anaerobic pathways that kick in when the intensity rises.
The five zones, broadly, are:
Zone 1 — Very light, recovery pace. Think brisk walk or slow jog.
Zone 2 — Easy aerobic effort. Conversational, comfortable, sustainable.
Zone 3 — Moderate effort. The famous "grey zone", hard enough to feel like work, not hard enough to drive the best adaptations.
Zone 4 — Hard. Lactate threshold territory. Sentences become difficult.
Zone 5 — Maximum effort. Sprinting, racing, anaerobic work.
The critical thing to understand is where most recreational runners actually spend their time: in Zone 3. It feels productive. You finish a run tired and sweaty, convinced you've worked hard enough. But physiologically, Zone 3 is the worst of both worlds, too intense to build the aerobic base that comes from Zone 2, and not intense enough to deliver the performance gains of Zone 4 and 5. Exercise physiologists have a blunt name for it: the grey zone, or the junk zone.
The Science Behind Zone 2
Mitochondrial Biogenesis — Building Your Engine
The central mechanism behind Zone 2 training is one of the most exciting processes in exercise physiology: mitochondrial biogenesis, or the creation of new mitochondria in your muscle cells.
Mitochondria are the energy factories of your cells. The more you have, and the more efficiently they function, the more aerobic capacity you possess. Zone 2 training is uniquely powerful at stimulating this process. A 2024 systematic review published in Sports Medicine, analysing data from 5,973 participants across 353 studies, found that endurance training increased mitochondrial content by an average of 23%. More mitochondria means your muscles can produce energy more efficiently at every intensity level, not just during easy runs, but when you push hard too.
Exercising in Zones 1 and 2 improves mitochondrial number, function, flexibility, efficiency, and fitness, in ways that Zone 3 and above do not replicate as effectively.
Fat Oxidation — Teaching Your Body to Burn the Right Fuel
Zone 2 is the intensity at which your body most efficiently uses fat as its primary fuel source. This matters far more than most runners appreciate. Fat is an almost inexhaustible energy source, even very lean athletes carry tens of thousands of calories stored as fat, whereas glycogen (stored carbohydrate) is limited to roughly 90 minutes of sustained effort before it runs low.
Zone 2 training improves overall metabolic efficiency by training the aerobic energy system to primarily burn stored fat for fuel rather than carbohydrates. The better your body becomes at oxidising fat, the longer you can run before hitting the wall, and the more you preserve your glycogen stores for when you truly need them, the final kilometres of a long race, or a decisive hill.
Lactate Threshold — The Gateway to Speed
As intensity increases, your muscles begin producing lactate faster than your body can clear it. The point at which lactate begins to accumulate, the lactate threshold, is one of the strongest predictors of endurance performance. Zone 2 training directly raises this threshold.
By training the slow-twitch, fatigue-resistant Type I muscle fibres that dominate Zone 2 work, you raise the intensity at which lactate begins to accumulate, allowing you to sustain faster paces at sub-threshold effort.
The practical result is profound: after months of consistent Zone 2 training, you'll find that your comfortable pace has become noticeably faster, not because you've been running fast in training, but because your aerobic engine has grown powerful enough that what once required a hard effort now falls comfortably within easy range.
Cardiac Adaptation — A Stronger Heart
Sustained low-intensity cardio increases stroke volume, the amount of blood the heart pumps per beat, and lowers resting heart rate over time. A stronger, more efficient heart delivers more oxygen to muscles with each beat, reducing the overall cardiovascular cost of any given pace. This is the physiological foundation of aerobic fitness.
The 80/20 Principle — Elite Athletes Know This
Perhaps the most compelling evidence for Zone 2 training comes from studying how the world's best endurance athletes actually train. Exercise physiologist Stephen Seiler's research found that world-class endurance athletes typically spend about 80% of their training at low intensity, with the remaining 20% reserved for high-intensity work. Very little falls in the moderate Zone 3 grey zone between the two.
A 2022 update on this body of literature showed that world-leading track and marathon runners spend over 80% of their training volume within the easy aerobic Zone 2.
Esteve-Lanao et al. (2007) found that recreational runners saw greater race improvements from a polarised model emphasising Zone 2 over threshold work. The takeaway is clear: this isn't just elite runner theory. It translates to recreational runners too.
The Benefits of Zone 2 Running
The science translates into a remarkable and wide-ranging list of practical benefits:
Greater endurance. A larger aerobic base means you can run further before fatigue sets in. Runners who commit to Zone 2 training consistently find their comfortable running distances growing, often dramatically, over weeks and months.
Faster recovery. Lower-intensity training doesn't beat up your body the way hard sessions do. Zone 2 runs can actually function as active recovery, clearing waste products from muscles while still building fitness. This allows higher overall training volumes without the injury risk that comes from running hard every day.
Improved efficiency at all paces. Because Zone 2 raises your aerobic capacity and lactate threshold, your hard runs and races benefit too. The aerobic base built in Zone 2 supports better performance right across the intensity spectrum.
Reduced injury risk. A well-developed aerobic base reduces fatigue and the risk of musculoskeletal injuries during demanding activities. A higher aerobic capacity lowers the relative cardiovascular cost of physical activity, meaning tasks place less strain on your body, enabling you to handle more work with less fatigue and recover faster between bouts of exertion.
Metabolic health benefits. Zone 2 training can have a dramatic impact on overall health, improving metabolic fitness and flexibility in ways that benefit far more than running performance.
Enjoyment. This might sound unscientific, but it is real and significant. Running at an intensity that doesn't leave you gasping and drained changes the emotional experience of the sport. You finish feeling good rather than depleted. The run becomes something to look forward to rather than endure.
How to Find and Achieve Zone 2
Calculating Your Zone 2 Heart Rate
The simplest starting point is the percentage of maximum heart rate formula:
Zone 2 = 60–70% of maximum heart rate
Your estimated maximum heart rate is roughly 220 minus your age, though this is a population average with meaningful individual variation. A 40-year-old would have an estimated max HR of 180 bpm, putting Zone 2 between approximately 108 and 126 bpm.
For greater precision, the Karvonen method (or Heart Rate Reserve method) is more personalised, as it accounts for your resting heart rate:
Find your resting heart rate (check your pulse first thing in the morning, or use your watch's resting HR reading).
Calculate your Heart Rate Reserve: Max HR minus Resting HR.
Zone 2 = Resting HR + (50–60% of Heart Rate Reserve).
For example, someone with a max HR of 180 and a resting HR of 55 has an HRR of 125. Their Zone 2 would be approximately 55 + (62 to 75) = 117 to 130 bpm.
The most accurate method of all is a lactate threshold test, which requires lab testing or access to a metabolic testing service, but gives a truly individualised Zone 2 range.
The Talk Test — Your Built-In Zone 2 Detector
Before reaching for numbers, use your body. If you can hold a normal conversation with your running partner, you are probably in Zone 2. When you enter Zone 3, you should be able to speak a full sentence without gasping for oxygen, but not easily manage a longer conversation.
At Zone 2 intensity, you can speak comfortably but not sing. If speaking is effortless, increase pace. If it is difficult, slow down. It really is that simple as a starting guide, and it's one of the most reliable real-world checks available.
The Reality: It Feels Too Slow
Here is the honest truth that most new Zone 2 runners have to confront: it feels too slow. Uncomfortably, embarrassingly slow. Runners who are used to pushing themselves find Zone 2 faintly ridiculous, the pace can drop dramatically, especially on hills or into a headwind, and it can feel like you're barely running at all.
This feeling is real, and it is completely normal. It is also telling. The discomfort of running slowly is actually evidence that your aerobic base needs exactly this kind of work. If Zone 2 pace feels easy and natural, your aerobic engine is already well developed. If it feels absurdly slow and you keep drifting faster, it is a sign that you've been over-relying on higher-intensity effort, and your body hasn't built the aerobic foundation to make slow running feel efficient.
Trust the process. Within a few weeks, the pace that felt embarrassingly slow will begin to feel natural, and gradually that natural Zone 2 pace will creep faster.
When Zone 2 Gets Hard to Maintain
Zone 2 is a target intensity, not a target pace, and this distinction matters enormously on certain types of terrain and in certain conditions.
Hills
Gradients are the most common Zone 2 disruptor. Even a gentle incline can push your heart rate from Zone 2 into Zone 3 or Zone 4 within seconds, even if your pace drops considerably. Beginners and even experienced runners often need to incorporate walking intervals on hills to prevent their heart rate from spiking into Zone 3.
There is no shame in walking uphills during a Zone 2 run. The goal is to keep your heart rate within the zone, the method is secondary. Walk the hill, let your heart rate drop, and resume running once you're back in range. Many accomplished runners walk hills as standard practice, not as a compromise. On descents, take the free speed and let your heart rate recover.
Headwinds
Running into a significant headwind imposes an aerobic cost similar to running uphill. Your muscles work harder for the same forward progress, pushing heart rate upward. As with hills, the appropriate response is to slow your pace, or accept that conditions on that day will make strict Zone 2 harder to maintain, and rely more on the talk test than on absolute numbers.
Heat and Humidity
Hot weather pushes your heart rate up at any given pace, sometimes dramatically. On a very hot, humid day, the same pace that produces a Zone 2 heart rate at 15°C might produce a significantly higher heart rate. Your zones don't change, but your heart rate at a given effort does.
Because your heart rate will be elevated in the heat, you'll find that you're reaching higher zones with a slower pace, and that is fine. When training in the heat, reduce your average speed rather than trying to maintain your regular pace at a higher heart rate. Trust the talk test and breathe through your nose when possible. On hot days, your pace will be slower, your heart rate will read higher, and both are exactly right.
Cardiac Drift — Why Your Heart Rate Climbs on Long Runs
You may notice on longer Zone 2 runs that your heart rate gradually climbs even though you haven't changed pace or effort. This is cardiac drift, and it is a completely normal physiological response.
Cardiac drift occurs for most runners near the end of a long run or ride — heart rate trends upward despite holding the same pace. Dehydration can drive cardiac drift, but more likely in non-elite athletes, it is due to metabolic stress: you are beginning to use more Type 2 muscle fibres, which burn glucose and produce more lactate, making muscles less effective and requiring greater effort to maintain the same output.
The appropriate response to cardiac drift is to maintain effort and let heart rate drift, rather than slowing down to artificially keep the number constant. The best mitigation is good hydration before and during the run. As your Zone 2 fitness improves over months of training, cardiac drift on long runs will reduce, which is one of the clearest signs that your aerobic engine is strengthening.
How Your Smartwatch Can Help You Train Zone 2
Apple Watch
The Apple Watch displays your heart rate zone in real time during workouts. Start a cardio-focused workout such as an outdoor run, turn the Digital Crown to the Heart Rate Zone workout view, and the screen shows your Heart Rate Zone, heart rate, time in the current zone, and your average heart rate. After a session, the Fitness app on iPhone shows a graph detailing the estimated time spent in each zone.
By default, Heart Rate Zones are calculated based on your health data, but you can manually edit those zones. Go to Settings on Apple Watch, then Workout, then Heart Rate Zones, tap Manual, and enter your own lower and upper limits for each zone. This is important, because the default calculation uses the simple 220-minus-age formula which may not reflect your individual physiology. If you know your true maximum heart rate, entering your personalised Zone 2 range manually gives far more accurate guidance.
You can also set custom heart rate alerts during a workout. Swipe to the metrics screen and tap the heart rate display to set a custom alert range, for example, 120 to 140 bpm. Apple Watch will tap your wrist when you drift above or below the range. This wrist tap is invaluable for keeping you honest on hills and in headwinds.
For even greater accuracy, you can pair your Apple Watch with a chest strap such as the Polar H10 via Bluetooth, which gives more precise readings, particularly during sustained cardio.
Other Devices
Garmin, Polar, Wahoo and similar GPS watches all offer zone-based heart rate monitoring with similar capabilities. The principle is the same: set your personalised zones, monitor the live readout during your run, and review the zone breakdown afterwards to understand how your training is distributed.
The post-run zone distribution graph, showing what percentage of your run was spent in each zone, is one of the most revealing pieces of data available to any runner. Over time, tracking this distribution week by week gives a clear picture of whether your training is genuinely aerobic or whether you're drifting into the grey zone without realising it.
Runna — Where Heart Rate Data Becomes Meaningful Context
Hardware gives you the numbers. What you do with them is a different question entirely.
I've been using and recommending the Runna training app for a while now, and one of the things it does particularly well is take the raw heart rate data from your watch and give it genuine context within your training. After every run, Runna shows a detailed breakdown of exactly how much time you spent in each zone, not just a summary average, but the full picture of how your effort was distributed across the session. It's the kind of post-run feedback that makes a Zone 2 focus genuinely actionable rather than abstract.
What I appreciate most is how the app frames that data intelligently. Easy runs are explicitly designed to sit in Zones 1 and 2. If your data shows you spent a chunk of an easy session in Zone 3 or 4, that's not just a number, in the context of a structured plan, it's a clear signal to ease back. Runna calculates heart rate zones using the standard industry formula and syncs them with Strava, so your data stays consistent across platforms. It also allows you to manually edit your zones if you know your own numbers from testing, which, as we've discussed, is always worth doing.
One feature that's genuinely useful for Zone 2 work is the ability to train to heart rate rather than pace. On hilly routes, hot days, or headwind-heavy runs, exactly the conditions that make strict pace targets meaningless, Runna lets you use your heart rate as the effort anchor instead. The goal becomes staying aerobic, not hitting a split, which is precisely the right approach.
For runners new to the concept of structured training and zone-based work, having a coaching app that weaves this thinking into every session removes a lot of the guesswork. You don't need to be an exercise physiologist to benefit from it, you just follow the plan, watch the post-run zone breakdown, and over time, the data tells its own story.
If you'd like to try it, I have an exclusive two-week free trial available, no commitment, just enough time to run a few sessions and see the feedback for yourself. Use code ANDY2 at the link below:
Factors That Affect Zone 2 — Beyond Pace and Terrain
Your Zone 2 heart rate is not a fixed number. Several factors can push your heart rate higher at any given effort:
Illness. Even mild illness, a cold, a low-grade infection, the early stages of flu, elevates resting and exercise heart rate significantly. If you're under the weather and your heart rate reads higher than usual, that's your body telling you it's under physiological stress. Running Zone 2 when ill isn't harmful in mild cases, but you must judge by the numbers, not your usual pace. You may find yourself shuffling at walking pace to stay in zone, and that is the correct response.
Fatigue and poor sleep. Poor sleep or high stress can elevate your heart rate. An exhausted runner will reach Zone 3 at a pace that normally sits comfortably in Zone 2. This is a feature, not a bug, it's your watch telling you that your body is already under load, and pushing harder would be counterproductive.
Overtraining. Paradoxically, a chronically elevated resting heart rate and difficulty staying in Zone 2 at comfortable paces can be a sign of overtraining, the body's stress systems are firing even at rest. Zone 2 is both a training zone and a diagnostic tool.
Medication. Some medications, particularly beta-blockers used for blood pressure or heart conditions, artificially suppress heart rate. Runners on such medication should work with their doctor or use perceived effort and the talk test rather than strict heart rate zones, as the numbers will not reflect true physiological effort.
Altitude. At elevation, reduced oxygen availability raises heart rate at any given pace. The same Zone 2 effort at sea level will produce a higher heart rate at altitude.
Caffeine. Pre-run coffee can elevate heart rate by 5-10 bpm for some runners, nudging you into Zone 3 at a pace that would normally sit in Zone 2. Worth knowing if you're doing a structured Zone 2 session.
A Real Story: How Zone 2 Changed Everything
The best evidence for Zone 2 training isn't always found in a lab. Sometimes it's found in the data on a family member's Apple Watch.
Six months ago, my wife came to me with a question about her running. She's an accomplished casual runner, comfortable covering up to 10-12km, with a weekly mileage of around 20-25km. She genuinely enjoys running, but she'd hit a ceiling she couldn't explain: anything beyond her regular distances felt disproportionately hard. Progress had stalled, and she was struggling to understand why.
We sat down with her Apple Watch data and had a look. What I saw was immediately revealing. The vast majority of her running was in high Zone 3, with a substantial chunk pushing into Zone 4. She was working harder than she needed to on every run, not through any lack of effort or discipline, but simply because she'd never had reason to question the pace she'd settled into over years of running. It was the pace that felt like running to her.
We talked about Zone 2. About the science, about the 80/20 principle, about why slowing down builds the engine that makes everything else faster. And then came the hardest part: we asked her to actually slow down.
Her immediate reaction? It feels too slow. That is the almost universal response, and it's the thing that stops many runners from ever making the shift. The pace required to keep heart rate in Zone 2 felt, in her words, like she wasn't really running.
But she persisted. A couple of weeks in, something shifted. The data showed it first, the majority of her runs were now clearly in Zone 2, with small excursions into Zone 3 on inclines and into headwinds (which, living in North Devon, are a near-constant companion). Her body had adjusted. The pace that had felt absurdly slow was beginning to feel normal.
The measure of success, though, wasn't the data. It was a sentence she said a few weeks into the experiment: I enjoy running more than I did before.
That, for me, is the heart of what Zone 2 gives recreational runners. Not just better fitness, not just the ability to run further, though both of those came. The experience of running itself changed. Without the accumulated fatigue of running too hard too often, every run became something to look forward to. The sport became enjoyable again in a different and richer way.
And in recent weeks, there's been talk of something I genuinely didn't expect: a marathon. Six months ago, extending beyond 12km felt like a struggle. Now, the idea of 42km is not just thinkable, it's something she's actively considering. That progression, from "why is running hard?" to "maybe I'll run a marathon," sits entirely on the foundation of Zone 2 work. To see that transformation, to watch running become a source of real satisfaction and excitement rather than a plateau, is genuinely wonderful.
Getting Started With Zone 2
Here is a practical framework for introducing Zone 2 work into your running:
Calculate your zone. Use 220 minus your age to estimate your maximum heart rate, then multiply by 0.60 and 0.70 to find your Zone 2 floor and ceiling. Better yet, use the Karvonen method if you know your resting heart rate, or manually enter a personalised range into your watch.
Set up your watch. Configure heart rate zones in your device settings and, if possible, enable an alert when you exceed the top of Zone 2. The wrist tap is a powerful reminder on hills and when you unconsciously speed up.
Accept the pace. In the first weeks, Zone 2 will probably feel too easy. You may need to slow down considerably, perhaps to a pace that feels closer to a jog than a run. This is correct. Go with it.
Use the talk test. Throughout your run, check in with your breathing. Full, comfortable sentences? Good. Gasping or short phrases? Slow down.
Walk the hills. There is no compromise in this. Walking to stay in zone is Zone 2 training. Running hard uphill is not. Keep your effort aerobic, whatever the terrain demands.
Give it time. To improve your aerobic running base, 3 to 6 hours of Zone 2 running per week is effective for most recreational athletes, distributed across 3 to 6 training days, with individual sessions lasting 45 to 90 minutes. The adaptations are real but gradual, expect to begin noticing meaningful changes after 6 to 12 weeks of consistent work.
Review your data. After each run, check your zone distribution. Over weeks and months, track what percentage of your running is genuinely in Zone 2. That graph is your progress report.
The Bigger Picture
Zone 2 running asks something that goes against the grain of modern culture: it asks you to be patient, to trust slow progress, and to find value in easy work. The rewards, a stronger aerobic engine, the ability to run further, a reduced injury risk, and quite possibly a rekindled love of the sport, arrive not in days, but over weeks and months of consistent, unhurried effort.
The world's best endurance athletes have known this for decades. Most recreational runners are only just discovering it.
Slow down. Run easy. Build the base. And see where it takes you.
Frequently Asked Questions
What is Zone 2 running?
Zone 2 running is sustained aerobic exercise performed at 60 to 70% of your maximum heart rate, an effort level where you can hold a full, comfortable conversation without gasping for breath. It targets your body's aerobic energy system, primarily burning fat for fuel and stimulating the development of mitochondria in your muscles. It is considered the foundational intensity for building endurance and long-term running performance.
How do I know if I'm running in Zone 2?
The simplest check is the talk test: if you can speak in full, comfortable sentences while running, you are likely in Zone 2. If speech is easy and effortless, you may be in Zone 1 and could pick up the pace slightly. If you can only manage short phrases or feel the need to pause for breath, you have drifted into Zone 3 or above and should slow down. For a more precise measure, use a heart rate monitor and aim for 60–70% of your maximum heart rate.
Is Zone 2 running too slow? It feels like I'm barely running.
Yes, and that feeling is completely normal, and actually telling. Most recreational runners have become accustomed to running harder than they need to, which means their Zone 2 pace feels uncomfortably slow at first. This is a sign that your aerobic base needs exactly this kind of work. Within a few weeks of consistent Zone 2 training, the pace that felt embarrassingly slow will begin to feel natural, and over months, your natural Zone 2 pace will gradually become faster as your aerobic engine grows stronger.
How do I calculate my Zone 2 heart rate?
The simplest method is to estimate your maximum heart rate (220 minus your age) and then calculate 60–70% of that figure. For example, a 40-year-old would have an estimated max HR of 180 bpm, putting Zone 2 between 108 and 126 bpm. For a more personalised result, use the Karvonen method, which also factors in your resting heart rate. The most accurate method is a lactate threshold test, available through sports science labs and some performance-focused running coaches.
How long should a Zone 2 run be?
Zone 2 benefits accumulate with duration. Sessions of 45 to 90 minutes are most effective for driving the mitochondrial adaptations that make Zone 2 so valuable. Shorter runs of 20 to 30 minutes are better than nothing, but provide a reduced stimulus. For most recreational runners, 3 to 6 hours of Zone 2 work per week distributed across several sessions is the recommended target for meaningful aerobic development.
Can I do Zone 2 running on hills?
Hills make true Zone 2 running very difficult, because even gentle gradients can push heart rate into Zone 3 or 4 within seconds. The solution is to walk uphills whenever your heart rate rises above your Zone 2 ceiling. Walking the hill keeps your effort aerobic, which is the goal, the specific pace or gait is secondary. On descents, the free speed allows your heart rate to recover. Over time, as your aerobic fitness improves, you may find you can run more of the hill before needing to walk.
Does illness or poor sleep affect my Zone 2 training?
Yes, significantly. Both illness and poor sleep elevate your resting and exercise heart rate, meaning your body is already under physiological stress before you begin running. On such days, you may find that your Zone 2 heart rate ceiling is reached at a much slower pace than usual, sometimes barely above a walk. This is your body communicating clearly, and the right response is to follow the numbers rather than your habitual pace. If you are genuinely unwell, rest is almost always the better option over a forced easy run.
What is cardiac drift, and should I worry about it?
Cardiac drift is the gradual rise in heart rate during a long run even when pace and effort remain steady. It is a normal physiological response caused primarily by dehydration and the increasing metabolic demands of sustained exercise. It does not mean something is wrong. The appropriate response is to maintain your effort level and let your heart rate drift, rather than slowing down to artificially hold it at a fixed number. Good pre-run hydration minimises the effect. As your Zone 2 fitness improves over months of training, cardiac drift on long runs will reduce noticeably.
How long before I see results from Zone 2 training?
Meaningful aerobic adaptations take time. Most runners begin to notice a difference, running the same routes at lower heart rates, or running further without fatigue, after 6 to 12 weeks of consistent Zone 2 work. The full depth of aerobic base building compounds over months and years. The process is gradual by design; the adaptations (mitochondrial density, fat oxidation efficiency, cardiac stroke volume) are structural changes that cannot be rushed but, once built, are remarkably durable.
Can Zone 2 training help me run a marathon?
Absolutely. Zone 2 training is the cornerstone of marathon preparation for athletes at every level. The marathon is almost entirely an aerobic event, the ability to sustain effort for several hours without depleting glycogen stores or accumulating excessive fatigue is precisely what Zone 2 builds. Many runners find that committing to Zone 2 work unlocks distances that previously felt impossible, because they have finally given their aerobic system the foundation it needs to support longer efforts.
How does the Runna app help with Zone 2 training?
Runna provides detailed post-run heart rate zone breakdowns after every session, showing exactly how much time you spent in each zone. Easy runs within the app are designed to sit in Zones 1 and 2, and the app supports training to heart rate rather than pace, which is particularly useful on hilly routes, in hot weather, or on headwind-heavy days where pace targets become misleading. You can also customise your heart rate zones within the app to reflect your personal physiology rather than relying on the default formula.
Try it free for two weeks using code ANDY2 at web.runna.com/redeem?code=ANDY2.
What's your Zone 2 story? Have you tried incorporating more easy miles into your training? Share your experience in the comments below.
About the Author
Andy Hood is an ultra and endurance runner based in North Devon, and a cancer survivor whose relationship with running was fundamentally transformed by a testicular cancer diagnosis in 2021. Rather than stepping back, Andy came back stronger, using running as a vehicle to raise awareness, inspire others, and fundraise for cancer charities. To date he has raised close to £30,000, taking on a series of self-designed challenges that include a 24-hour treadmill ultra, a 170-mile run to Land's End along the South West Coast Path, two completions of the 160km Tour du Mont Blanc, and a 50K run across London visiting twenty Krispy Kreme stores in aid of cancer charity ChemoHero.
When Andy isn't designing bold ultras with a charitable purpose, he is a proud Runna ambassador and the founder of Check Ya Balls, a men's underwear brand with a serious message about testicular cancer awareness. He writes about running, endurance, wellness and the lessons the trails teach us at runningwestwardho.co.uk, where you'll find race reports, training insights, and a perspective on running shaped by the knowledge that every mile is a privilege.
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