Easy Does It: Why You Should Target Zone 2 Cardio Workouts

You’re probably familiar with the phrase, “Slow and steady wins the race.” As it turns out, that guidance is worth following when it comes to planning how hard to make your daily cardio training.

A growing body of research shows that relatively mild “zone 2 cardio” exercise delivers significant health and fitness benefits. Bottom line? Fitness gains don’t necessarily require grueling training.

But can you truly get that much out of activities that don’t even get you out of breath? We asked exercise physiologist Christopher Travers, MS, to explain how it works.

What is zone 2 cardio?

Zone 2 training refers to moderate-intensity aerobic exercise that elevates your heart rate a wee bit. It’s the second step on a 1-to-5 heart rate zone scale, which reflects how hard your heart is working to power you through a workout.

In zone 2, your heart rate is at 60% to 70% of what your maximum heart rate could reach during an activity. (More on that later.)

“You’re not going to feel like you’re pushing it if you’re exercising in zone 2,” explains Travers. “It should feel like a comfortable workout effort and something that you can do for a longer period of time.”

Examples of zone 2 training

Any cardio activity can fall into zone 2 by adjusting your intensity level, says Travers. You can hit zone 2 through:

• Brisk walking, which usually means covering a mile on flatter terrain in 15 to 20 minutes (a stroll around the neighborhood in zone 1 won’t get the job done)
• Slow running at a pace that’s two to three minutes slower than what you would consider your “race pace”
• Cycling at a relaxed speed that you can easily maintain mile after mile
• Swimming laps at a slow-and-steady pace
• Elliptical or rowing machine workouts

“The key is to do the activity in a controlled manner,” emphasizes Travers. “Focus on just moving — not on how fast you’re doing it.”

Zone 2 cardio benefits

Maybe it’s a byproduct of “no pain, no gain” messaging, but the concept of dialing down cardio training just feels … well, wrong. It seems odd to think that lower-intensity exercise can boost your fitness.

But studies show that it can. Here are a few gains you can achieve by doing more training in zone 2.

Fat burning

It’s easy to assume that pushing yourself to your max is the most effective way to burn fat and make your body trim. More huffing and puffing and sweating should equal more weight loss, right?

Wrong.

The higher your heart rate soars, the more your body uses sources other than fat — namely carbohydrates (glycogen) and protein — for fuel.

“When your heart rate increases, you’re not taking in as much oxygen,” explains Travers. “You can’t burn fat fast enough when you have less oxygen, so your body turns to other readily available energy sources.”

Exercising in zone 2 (as well as zone 1) prioritizes fat burning and never pushes your body to the point where it needs to scrounge up fuel from other resources.

Improved heart and lung function

Building your aerobic base helps your heart and lungs by:

• Strengthening your heart muscle to pump more blood with each beat
• Improving mitochondrial function within your cells to create more energy for your body
• Increasing the number of capillaries, or small blood vessels, around muscles to improve blood flow
• Boosting red blood cell production to deliver more oxygen to muscles

Reduced injury risk

Lower-intensity workouts place less strain on your muscles, tendons, ligaments and other important body parts that keep you going.

“In zone 2, you’re working your body in a way that minimizes the chance of your body not being able to handle the load,” says Travers. “Elite athletes spend a lot of time in zone 2 to build strength and endurance with less injury risk.”

It’s also easier to bounce back and recover from a zone 2 workout, as your body isn’t being overtaxed. That can reduce the likelihood of overuse injuries driven by too much high-intensity training.

Endurance gains

The idea behind zone 2 training isn’t necessarily to work less. It’s to work longer. Most zone 2 activities last at least 30 minutes — and many extend far, far beyond that time.

That’s NOT something you can physically do with high-intensity interval training (HIIT), where you go all out for shorter bursts.

“Basically, with zone 2 activities, you’re trading a higher intensity level for more time investment,” clarifies Travers. “You’re training your muscles to overcome fatigue and to keep going for longer.”

How to know if you’re in zone 2 cardio

As we mentioned, zone 2 training is categorized as exercise where your heart rate is between 60% to 70% of your maximum heart rate during an activity. Setting that target requires a bit of math.

The easiest way to estimate your max heart rate is through this formula: 220 – Your Age = Your Max Heart Rate. So, if you’re 40 years old, your max heart rate would be 180 beats per minute (bpm).

Zone 2 would be 60% to 70% of that number, or 108 to 126 bpm.

Not a math person? You don’t have to be! Another sign that you’re in zone 2 while exercising is if you can carry on a light conversation while doing the activity.

“If heart rate calculations feel like a stumbling block, don’t worry about getting fixated on running the numbers,” reassures Travers. “Focus on how your body feels when you’re exercising. The most important thing is just to get moving.”

For optimal cardiovascular health, the American Heart Association recommends at least 150 minutes per week of moderate-intensity aerobic activity. Zone 2 cardio falls in that category.

Now, can you gain benefits from higher, heart-pounding zones? Of course! Incorporating higher-intensity exercises that target zone 3, 4 and even 5 into your routine can push your fitness to higher levels.

But don’t feel like you have to go hard to see benefits.

“If you’re pushing your heart rate higher than what it is at rest, even if it’s a little bit, you’re working to improve your cardiovascular health,” Travers encourages. “The benefits you see with zone 2 training are proof that you don’t need to go overboard.”