If you’ve spent any time in the fitness space lately, you’ve probably heard people talking about zone 2 cardio. It’s often described as the “secret” to better endurance, improved metabolism, and even longevity. But what exactly is it—and is it really worth it?
Let’s break down what it is and if it’s right for you and your goals.
What Is Zone 2 Cardio?
Zone 2 cardio, also known as steady state cardio, refers to exercising at a moderate intensity where your heart rate sits at roughly 60–70% of your maximum heart rate. It’s one of five commonly used heart rate zones, each representing a different level of effort. Elite endurance athletes typically use fancy gadgets to ensure they are in zone 2, but most of us will do just fine simple body awareness cues.
Practically speaking, zone 2 feels like:
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A brisk walk or easy jog
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Cycling at a steady, comfortable pace
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Elliptical machine
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Hiking
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Any activity where you can still hold a conversation without gasping for air
This is often called the “conversational pace.” Not too easy, but not too hard.
How Does Zone 2 Work?
Zone 2 training targets your body’s aerobic energy system, which relies heavily on oxygen in order to produce ATP—our primary energy source.
At this intensity:
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Your body primarily burns fat for fuel, rather than carbohydrates
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Your muscles increase their number of mitochondria (the “powerhouses” of cells)
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You improve your ability to transport and use oxygen efficiently
Over time, this leads to better metabolic flexibility—your body becomes more efficient at switching between fuel sources depending on the demand (Goodpaster, 2018). When your body isn’t using mostly fat or mostly glucose to power your activity, you can have better overall performance, power, and endurance.
What are the Benefits of Zone 2 Cardio?
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Builds a Strong Aerobic Base
Think of zone 2 as the foundation of your fitness. A stronger aerobic system supports everything from running faster to recovering better between workouts.
- Enhances Fat Burning
Because you’re working at a lower intensity, your body relies more on fat as a fuel source. Over time, this can improve body composition and metabolic health.
Next time you’re at your gym, go to the treadmill and you’ll find the button that says “fat-burning zone.” This setting is targeting zone 2 fitness. However, it’s important to note that all other forms of cardio, like HIIT, are just as effective for fat loss (Kramer, 2023).
- Improves Heart Health
Zone 2 training strengthens your heart, increasing stroke volume (how much blood your heart pumps per beat) and overall cardiovascular efficiency.
- Supports Longevity
Consistent moderate-intensity exercise is strongly associated with reduced risk of chronic diseases like heart disease, type 2 diabetes, and metabolic syndrome (San-Millan, 2023). This is because zone 2 cardio has been shown to boost mitochondrial health.
Thankfully, however, all physical activity has been shown to improve mitochondrial health (Porter, 2016). So no need to drop everything and speedwalk down the block.
- Easier to Recover From
Unlike high-intensity workouts, zone 2 sessions don’t heavily tax your nervous system. That means you can do them more frequently without burning out.
It can also be helpful while you’re recovering from your strength training sessions.
Who Is Zone 2 Cardio For?
Well, pretty much everyone.
Beginners
If you’re new to exercise, zone 2 is a safe and sustainable way to build fitness without overdoing it.
Endurance Athletes
Runners, cyclists, and triathletes often spend a large portion of their training in zone 2 to build endurance and efficiency.
Busy Professionals
It’s low stress, doesn’t require complicated programming, and can be done while listening to a podcast or taking a call.
People Focused on Health and Longevity
If your goal is to stay healthy, improve energy, and age well, zone 2 is one of the most researched approaches.
What are the Downsides?
Zone 2 isn’t perfect, and it’s important to understand its limitations.
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It Takes Time
Zone 2 workouts are typically longer—often 45-60 plus minutes—to be effective. That can be a barrier if you’re short on time or have a hectic schedule.
- It Can Feel “Too Easy”
Some people find it boring or question whether it’s doing anything because it doesn’t feel intense. Ironically, that’s exactly the point.
- Limited for Speed and Power
If your goal is to sprint faster, jump higher, or build explosive strength, zone 2 alone won’t get you there. You’ll need higher-intensity training too.
- It Can Be Tricky to Measure
Estimating your true zone 2 range isn’t always straightforward. Generic formulas are rough estimates, not precise measurements.
- Not a Complete Fitness Plan
Zone 2 is a powerful tool—but it shouldn’t replace strength training or occasional high-intensity work if you want well-rounded fitness.
How to Get Started
If you’re curious about trying zone 2 cardio:
- Aim for 2–4 sessions per week
- Start with 30–45 minutes per session
- Use a heart rate monitor if possible
- Focus on staying at a pace where you can comfortably talk
Consistency matters more than perfection here.
Fitness trends tend to move in cycles. What feels new and cutting-edge today often echoes something that was popular years ago—just with a fresh label.
Training styles will always ebb and flow. When something comes back into the spotlight, it’s worth keeping a level head. No single food, workout, or supplement is ever going to be a magic fix.
The recent buzz around zone 2 cardio has been a positive shift in many ways. It’s encouraging more people—including myself—to prioritize aerobic work and rethink how they train.
At the same time, it’s also left some people feeling overwhelmed, like they need to follow a perfectly optimized plan to see results.
At Gnarly Nutrition, our focus is a bit different. Instead of chasing what’s theoretically “optimal,” the goal is what’s realistically sustainable. Do what you can with what you have. Choose activities you actually enjoy. Then show up and do them consistently—that’s where the real progress happens.
References
Goodpaster, B. H., & Sparks, L. M. (2017). Metabolic Flexibility in Health and Disease. Cell metabolism, 25(5), 1027–1036. https://doi.org/10.1016/j.cmet.2017.04.015
Kramer, A. M., Martins, J. B., de Oliveira, P. C., Lehnen, A. M., & Waclawovsky, G. (2023). High-intensity interval training is not superior to continuous aerobic training in reducing body fat: A systematic review and meta-analysis of randomized clinical trials. Journal of exercise science and fitness, 21(4), 385–394. https://doi.org/10.1016/j.jesf.2023.09.002
Porter, C., Reidy, P. T., Bhattarai, N., Sidossis, L. S., & Rasmussen, B. B. (2015). Resistance Exercise Training Alters Mitochondrial Function in Human Skeletal Muscle. Medicine and science in sports and exercise, 47(9), 1922–1931. https://doi.org/10.1249/MSS.0000000000000605
San-Millán I. (2023). The Key Role of Mitochondrial Function in Health and Disease. Antioxidants (Basel, Switzerland), 12(4), 782. https://doi.org/10.3390/antiox12040782
