How trendy Zone 2 workouts can boost heart health and happiness

If you're not dripping in sweat after a workout, did it even count? Pushing our bodies to the limit used to be a badge of honour, but these days, more fitness enthusiasts are embracing a gentler approach. They're using a buzzy training style that's all about being in the zone — Zone 2, that is. 

The best part about Zone 2 training? It's not as challenging as other forms of exercise, like high-intensity interval training (HIIT), which means it's an excellent option for beginners. In fact, you're probably already doing it without even knowing it. 

We reached out to doctors and scientists to learn more about this underrated form of exercise, its many health benefits and how you can try it for yourself. 

What is Zone 2 training?

Heart rate zones, developed by exercise scientists, are ranges of heartbeats per minute that correspond to different levels of exercise intensity. There are five heart rate zones, said Dr. Kim Connelly, a cardiologist with the Sports Cardiology Clinic at St. Michael's Hospital in Toronto. Zone 1 is the lowest-intensity zone, where you might be warming up or taking a casual walk and exercising at 50 to 60 per cent of your maximum heart rate. Zone 5 is when you are working as hard as you can, moving at 90 to 100 per cent of your maximum heart rate. 

Training within Zone 2 means exercising at 60 to 70 per cent of your maximum heart rate, which will generally be mild to moderate activity: your beats per minute (BPM) lifts, but you won't be left feeling winded and red in the face. "It's not that really intense level of exercise," said Connelly, which is one of the reasons he believes this type of training is gaining popularity. "Most people are actually able to achieve this level of fitness."

How to calculate your heart rate zones

The standard formula cardiologists use to determine a person's maximum heart rate is to subtract their age from 220. For example, if a person is 35, their maximum heart rate would be 185 (220 - 35 = 185). 

With this number, you can calculate your heart rate zones, said Connelly. So, a Zone 2 range (60 to 70 per cent of maximum heart rate) for a 35-year-old would be 111 to 129.5 BPM. Connelly recommends using a fitness tracker, like an Apple Watch, Garmin or Fitbit, to monitor your heart rate and measure your Zone 2 sweet spot. 

Folks who regularly compete in high-endurance events like Ironman races or triathlons may want to consider a VO2 max test, said Dr. Amir Majidi, a sports chiropractor and owner of Push Pounds Sports Medicine in Toronto. The test is typically done on a treadmill and involves wearing a special mask that measures the oxygen content of the air you breathe in and out. Of course, it isn't a must for everyone. Majidi said using the standard calculation works well for the general population.

What are the benefits of Zone 2 training? 

It protects your heart

Even though you may not be sweating, panting or puffing like an Olympic athlete, this level of exercise has incredible benefits, said Connelly. It reduces blood pressure and cholesterol, helps control weight, is helpful for diabetes and protects against heart disease and stroke — great news since heart disease is the second-leading cause of death in Canada. 

It gives you a mood boost

One of the most well-known benefits of sweating it out is the feel-good effects, thanks to the body's production of mood-boosting endorphins during exercise. That said, any mental health benefits from Zone 2 training are more likely related to physical activity in general, said Honey Mzadeh, a cardiovascular exercise physiologist at Push Pounds. 

Connelly hasn't seen any studies that look at whether there is a correlation between Zone 2 training and improved mental health, but he knows what he hears in his clinic. "What I see with my patients and other folks is … people feel better," he said. 

When it's coupled with being social, the benefits are doubled, he said. "If you can do it with a friend and it becomes social, all the better…. Then that often becomes a positive stimulus, like, if you want to get up at 7 a.m. [to exercise], you might be cozy in bed, but you know you have your friend waiting for you, [so] you're much more likely to get up and do it." 

It's gentle on the body

According to Mzadeh, Zone 2 training is "exercise at a level where your body mainly uses oxygen to produce energy efficiently … and it does that without building up a significant amount of lactate." 

Lactate is a byproduct of exercise that can contribute to muscle fatigue and discomfort, she said, often felt as that soreness in your muscles when giving it your all in the gym. "The idea is that when you stay in Zone 2, your muscles can efficiently clear lactate as quickly as it's produced," said Mzadeh, which ultimately allows for longer, more sustainable workouts. 

Training at a lower-intensity level means you're also less likely to get injured, Connelly said. Mzadeh agreed, adding that Zone 2 is an excellent option for active recovery days since it reduces the risk of overtraining. 

It contributes to healthier aging

During Zone 2 training, said Mzadeh, there are beneficial adaptations in the mitochondria, which are the part of our cells responsible for producing energy. Good mitochondrial health is linked to longevity, she said, because it enhances overall cellular health. "As we age, mitochondrial function declines, so it releases less efficient energy production and increases oxidative damage," she said, both of which accelerate the aging process. 

What are the best ways to exercise in Zone 2?

Speed walking, running, cycling, swimming — any activity that gets your heart rate up to the point where you can still carry on a conversation will do. Mzadeh said it's crucial that the activity is controlled and steady to avoid slipping out of the beneficial zone, so try to plan your route to avoid hills and inclines or opt for indoor training on a bike or treadmill. 

Connelly tells his patients to find what they like. "Some people are walkers, some people are runners, some people are riders — it doesn't really matter. If you like it, you're much more likely to do it," he said. Think taking the dog out for a jog or calling up a friend for a speed walking sesh and turning it into a standing social activity. "I'm a big believer in people choosing what they want to do, and it's got to be practical."

How long should you train in Zone 2?

Mzadeh recommends those starting out to aim for 30 minutes a session. "We need to be in Zone 2 for a while in order to see adaptation [in the mitochondria]," she said, noting that shorter periods of training more frequently won't produce the same effect. She also stressed the importance of incorporating other types of training into your regimen for longevity. "In our clinic … we generally say 80 per cent of your week should be in Zones 2 and 3, and 20 per cent should be in Zones 4 and 5." 

And if you get the urge to challenge yourself by, say, running a 5K or trying long-distance cycling, Connelly said Zone 2 training can help build a solid aerobic base. "If you do decide you want to do a more intense level of exercise, you've now got your body conditioned, all your muscles, your heart, your lungs, everything else, to be able to [do it]," he said. "You've done the background level of training that puts you in a really good position to be able to achieve whatever your goal might be."