What Is Zone 2 Cardio And Why Should You Do it?

As much as we love all the spicy, tough, feel-the-burn workouts, there’s a training style that is often massively underrated - zone 2 cardio. It doesn’t matter if you smash your heavy lifting goals, enjoy those fiery Pilates sessions, or let your heart rate soar with every HIIT session, but trust us on this one. You don’t want to neglect your zone 2 cardio. There’s a reason trainer Katie Martin often talks about the important role it plays in her own routine! 

Here’s everything you need to know about what zone 2 cardio is, the benefits it offers, and how to incorporate it in your workout schedule. 

What is zone 2 cardio?

The cardio element of this training style is self-explanatory and means any kind of aerobic exercise, but “zone 2” comes from the 5-zone system of heart rate training. According to the Cleveland Clinic, heart rate zones are based on a percentage of your maximum heart rate - the general way to calculate that being 220 minus your age.

Heart rate zones indicate how hard your heart is working to pump blood and keep up with the activity you’re doing, and range from zones 1 to 5. 

• Zone 1: Here you’re working at 50-60% of your maximum heart rate. The intensity feels very low and most of the calories burned while working at this level come from fat as your body has a plentiful supply of oxygen - essential for the metabolism of fat as fuel. You could maintain this intensity for a very long time and easily hold a conversation. Zone 1 could be compared to a leisurely stroll.

• Zone 2: Here you’re working at 60-70% of your maximum heart rate. The intensity is still light but slightly higher than zone 1, and the majority of the calories burned while working at this level come from fat as you still have a consistent supply of oxygen. You could maintain this intensity for a long time and continue to hold a conversation, but it’s a step up from a leisurely stroll. Zone 2 feels more like a brisk walk or easy jog. 

• Zone 3: Here you’re working at 70-80% of your maximum heart rate. The intensity is moderate, higher than in zone 2, and the source of energy is split between carbs and fat as your supply of steady oxygen is now lower. In zone 3, you could talk if you wanted to but would need to take some breaks to catch your breath.

• Zone 4: Here you’re working at 80-90% of your maximum heart rate. The intensity is high, you could only maintain it for a short workout or short bursts, and your body is burning carbs as its source of fuel as it doesn’t have a plentiful supply of oxygen. In other words, breathing is a struggle. In zone 4, you can only get a few words out at a time.

• Zone 5: Here you’re working at 90-100% of your maximum heart rate. The intensity is very high, you’re working at your absolute max, and you could only maintain it for a few minutes - if that! Your body is burning carbs as its source of fuel, and talking is out of the question.

Since the rise of high-intensity interval training (HIIT), it’s common to think zone 4 and 5 are the most ideal places to train in for progress and results and that working out at a lower intensity is best-suited to beginners or active recovery days, but zone 2 cardio is an incredible training modality that everyone should incorporate into their workout schedule. This is why Sweat programs - even the advanced ones - include weekly LISS sessions, aka low-intensity steady state cardio! 

When we talk about zone 2 cardio, we’re referring to low-intensity cardio sessions that remain at a low intensity for the entire duration of the session. It’s not a warm-up. There aren’t any bursts of high-intensity movement. You just hang out in that low intensity zone the entire time. When you finish, it’s generally not because you’re tired and can’t go on, but because you’ve hit the duration you were aiming for.

Why is zone 2 cardio so good for you? 

A helpful analogy to think about fitness intensities is to imagine a pyramid. The foundation of this pyramid is your base cardio fitness, built up by regular low-intensity or zone 2 cardio. If you want to add any extra, more intense workouts such as HIIT training or heavy lifting, you ideally want your base to be mighty strong, your energy systems to be efficient, and your recovery to be on point. How do you do that? You make zone 2 cardio a priority.

Cardio fitness

Exercising at this lower intensity actually improves your ability to train at higher thresholds. It increases your aerobic capacity, meaning your body has an increased ability to use oxygen efficiently, and your heart and lungs get better at taking in oxygen and transporting blood to your muscles. Zone 2 cardio can improve blood flow and help your body to use energy more efficiently by improving your mitochondrial flexibility, meaning improved metabolic health, better endurance and working out with greater ease in zones 3, 4 or 5.

A 2003 study investigating the relationship between the volume and intensity of exercise training, and regulation of heart rate and blood pressure, found that moderate exercise training for three months decreased blood pressure and heart rate and increased cardiovascular variability. A heart health hatrick.

Longevity and overall health

Spending more time in this training zone - whether you’re a newbie to fitness, simply trying to live a healthier life or you’re an elite athlete - can have a robust effect on your overall health, longevity and disease prevention. Mayo Clinic says aerobic activity like zone 2 cardio can help to reduce the risk of cardiovascular disease, Type 2 diabetes, metabolic conditions, dementia and some cancers.

Energy, performance and recovery

After including zone 2 training in your routine for a while, it’s natural to find that your energy levels are higher (during workouts and in general), what was once hard now feels much easier, your endurance has improved, and your recovery time (between sets and after each workout) is faster due to improved circulation. 

One 2022 study aimed to investigate whether low-intensity exercise improves energetic recovery and general endurance in professional soccer players with a nine-week program, and it did! 

Intense workouts and strength training both have their own unique benefits, but even an advanced training plan should include low-intensity cardio.

Body composition, fatigue and injury

If weight management or improving your body composition is a goal of yours, zone 2 cardio can support you to achieve that given fat is used as the primary source of fuel. To set the record straight, if you’re following a program like Lift with Laura, low-intensity cardio will not undo your strength gains in the gym. 

Not to mention, exercising at a lower intensity is generally very friendly on your joints and doesn’t come with the risk of overtraining, fatigue or injury, making it a great foundation of any sustainable fitness routine.

Sweat trainer Katie Martin is a huge fan of zone 2 cardio and says it’s a key component of her weekly routine, which includes a mix of running, strength training and Pilates. 

“Zone 2 training allows beginners to establish a solid aerobic foundation without pushing their bodies to the limit. This steady progress is sustainable over the long term, reducing the likelihood of burnout and making it easier to stick to a consistent training routine,” she says.

Zone 2 cardio examples

Including zone 2 cardio in your weekly routine can be as simple as going for a 30-60 minute brisk walk a few times a week (we love to throw on a podcast or audiobook), but if walking isn’t your thing, there are plenty of other ways to reap the benefits. You could also try:

• Cycling

• Rowing

• Rollerblading

• Swimming

• An easy jog or elliptical pace

The hardest part about zone 2 cardio for many people isn’t that it’s physically challenging, but that it can be hard to stay in that low-intensity sweet spot for such a long time. In other words, people find it boring. 

When your fitness builds, it’s natural to want to pick up the pace and push yourself, but then you’re immediately entering zone 3 or 4. If you find it boring, we get it! That’s why many of our trainers and women in the Sweat Community enjoy walking on the treadmill while watching their favourite shows, or listening to music, podcasts or audiobooks.

How long should your zone 2 cardio sessions be?

This depends on what your overall workout schedule looks like. The general recommendation from the American Heart Association is to get at least 150 minutes per week of moderate-intensity aerobic activity or 75 minutes per week of vigorous aerobic activity, or a combination of both, ideally spread throughout the week. 

If zone 2 cardio is all you’re doing for exercise, this could mean five 30-minute brisk walks per week, or three 50-minute sessions. Because Sweat programs already have weekly strength and/or HIIT workouts, they generally only include two low-intensity steady-state cardio sessions.

Look at your weekly schedule, do the math, and figure out what would work best for you! And remember, more isn’t always better. If you’ve been training hard every day, maybe now is the perfect time to swap some of those sessions for some gentle cardio, rather than just adding more exercise in. Instead of hurtling towards burnout or injury, we want you to find balance, build that strong aerobic base and reap the benefits!

What’s the best way to measure zone 2?

For most people, the easiest way is to use a fitness tracker or smart watch that has heart rate training functionality. If you don’t have a fitness tracker, the best way is to use the “talk-test” where you make sure you’re exercising at an intensity that would allow you to easily maintain a conversation without needing to stop to catch your breath.

If you’ve always wondered why low-intensity steady-cardio is such a strong, recurring element in Sweat programs, this is why. Zone 2 cardio isn’t just for beginners or chill recovery days, it’s for everyone and the benefits to be gained are not things you want to miss out on.