What is Zone 2 Cardio?

When you see people on treadmills, the settings they use to get into a Zone 2 heart rate can be all over the place. That’s because the right speed and incline depend on everything from the machine's brand to your personal fitness level and weight. Instead of chasing specific numbers, it’s much more effective to learn what Zone 2 actually feels like.

One more thing: before you start any serious cardio, we recommend boosting your metabolism through NEAT (Non-Exercise Activity Thermogenesis). In simple terms, this just means getting more active in your daily life. Aim to increase your step count to 10,000, 15,000, or even 20,000 steps a day. A higher step count burns more calories and can accelerate your weight loss. You can find helpful strategies for this in our Step Count Progression guide.

Think of Zone 2 as a moderate intensity level where you can still hold a conversation but definitely couldn't sing a song. Your breathing is steady but a little deeper than normal. At this level, you’re primarily training your aerobic system and telling your body to burn a higher percentage of fat for fuel compared to more intense workouts. This is the sweet spot for increasing your mitochondrial density, boosting metabolic efficiency, and getting better at fat utilization.

To find your target range, you can use a simple formula:

• First, estimate your max heart rate (HR) by subtracting your age from 220.
• Your Zone 2 range will be about 60-70% of that number.

For example, if you're 30 years old, your estimated max HR is 190 beats per minute (bpm). That puts your Zone 2 target between 114 and 133 bpm. A fitness band can help you track this with decent accuracy.

Choosing Your Zone 2 Activity for Fat Loss and Joint Health

Fast Walking Walking is a fantastic choice for almost everyone, burning around 200 to 300 calories per hour depending on your pace and weight. You can do it every day with very little risk of injury.

Cycling (Stationary or Road) If you have joint concerns, cycling is an excellent alternative. It burns anywhere from 300 to 500 calories an hour and makes it easy to lock into a steady heart rate for the entire workout.

Swimming (Slow, Steady Laps) For a full-body, low-impact workout, nothing beats swimming. It's especially great for heavier individuals and can burn between 400 and 600 calories per hour.

Let's see how this works in practice. Imagine Aman, who weighs 75 kg (about 165 lbs), decides to add four 45-minute cycling sessions to his weekly routine. Moderate cycling has a MET value of roughly 6.8. Based on the formula (6.8 METs × 75 kg × 0.75 hours), he’ll burn about 382.5 calories each session. Over a week, that's an extra 1530 calories burned. Since it takes a deficit of about 7700 calories to lose a kilogram of fat, his new cycling habit could help him lose around 0.2 kg (nearly half a pound) a week from exercise alone. If he’s already losing 0.5 to 0.6 kg through his diet, he could see a total weekly fat loss of 0.7 to 0.8 kg.

Finding Your Zone 2 on a Treadmill

Since everyone's fitness level is different, your ideal treadmill settings will be unique. Here are some starting points:

• If you're just starting out (e.g., over 80 kg and mostly sedentary), you might hit Zone 2 with a slow walk. Try a speed of 4 to 5 km/h (2.5–3.1 mph) with an incline of 0 to 2%.
• For moderately active people (weighing around 60–80 kg), a brisk walk or a slow jog is often needed. A good starting point is a speed of 5 to 6.5 km/h (3.1–4 mph) and an incline of 3 to 5%.
• If you're already quite fit (under 60 kg), you'll likely need a light jog or a steeper incline to get your heart rate up. Try starting at 6.5 to 8.5 km/h (4–5.3 mph) with an incline of 1 to 3%.

How to Test and Confirm Your Zone 2

Here’s a simple way to dial in your Zone 2 on the treadmill:

1. Begin by walking at 4 km/h with a 0% incline.
2. Every few minutes, slightly increase either the speed or the incline.
3. Keep an eye on your heart rate using your fitness band or the machine's pulse sensors.
4. The most reliable method is the "talk test." If you can speak in full sentences without gasping, you're probably in Zone 2. If you can only get a few words out, you’ve gone too high.
5. Once you find the settings that keep your heart rate stable in that 60-70% range, you've found your zone.

Are Cheap Fitness Bands Accurate Enough?

So, can you trust an affordable fitness band like the Huawei Band 9 for this? For steady-state cardio, the answer is yes. These devices use optical (PPG) sensors on your wrist, and while they aren't perfect, their accuracy is generally quite acceptable. During rhythmic activities like walking or cycling, the error range is typically only 3 to 5 bpm compared to a medical-grade chest strap. They become less reliable during high-impact or jerky movements, but for Zone 2, they work well.

This isn't just an opinion; it's backed by research. A 2020 study by Wallén et al. found that wrist sensors had an error rate below 5% during moderate exercise. Similarly, a 2017 study by Gillinov et al. concluded that optical monitors were sufficiently accurate for treadmill walking when compared to chest straps. For finding and maintaining your Zone 2, a budget-friendly band is a reliable tool, especially when you combine its data with the talk test.

References

• Coyle, E.F. (1995). Integration of the physiological factors determining endurance performance. Exercise and Sport Sciences Reviews, 23, 25–63.
• Støren, Ø. et al. (2017). Improved running economy via strength training. Journal of Strength and Conditioning Research, 31(4), 1040–1046.
• Gillinov, S. et al. (2017). Variable accuracy of wearable heart rate monitors during exercise. Cardiology, 138(2), 97–103.
• Wallén, M. et al. (2020). Accuracy of wrist-worn optical HR sensors during moderate exercise. Eur J Sport Sci, 20(8), 1039–1046.