Why Zone 3 Cardio Is Just as Good as Zone 2

There arebenefits to training in heart rate zone 2, and youve probably heard all about them.

Surprise: You dont lose the benefits of zone 2 training.

Zone 3 is arguably just as good for you, or maybe even better.

Guess what zone 3 trainingalsodoes?

So why arent we all doing more zone 3 cardio?

Easy cardio is having a moment right now, so everybody is talkingabout doing more zone 2.

Your heart ticks up a beat?

Youre out of your zone.

Straight to workout jail!

Workout zones arent real

The most popularheart-rate zonesystems use zones that are divided up for convenient measuring.

They don’t have any precise relationship to what’s going on in your body.

The guideline to keep your easy cardio at a chatty pacedoescome from a scientific concept: the ventilatory threshold.

Imagine you start out at a walk, and every minute or so you increase your speed a bit.

That point is your ventilatory threshold, or VT (sometimes called VT1).

When athletes or coaches talk about easy pace or easy efforts, they usually want you below your VT.

But nopeconversational pace is closer to 80%, which is the top of zone 3.

And theytestedthe runners max heart rate, rather than using a formula based on age.

(Never trust the default formulas.)

(Hello,cozy cardio!)

If youre interested in calorie burn per hour, zone 3 is more efficient.

Cyclists sometimes call training in this range the sweet spot.

It gives you some of the advantages of harder training without making you too fatigued.

Your heart rate doesntonlytrack with your training effort; it also responds to a lot of other factors.

For example, itresponds to summer heat, showing you higher numbers in hot weather.

Some medications can alter your heart rate as wellbeta blockers, for example, notoriously lower your heart rate.

It’s less fatiguing than HIIT, but packs more of a punch than zone 2.

(Here’s one interesting studywhere this level of exercise worked even without dietary changes.)

This is a lot of exercise!

If you’re only exercising a few days a week, zone 3 is probably better.

Zone 1 is good for warmups, cooldowns, and the recovery periods between intervals.

Zone 2 is good for long sustained efforts.

It’s usually OK to do zone 2in place of a rest day.

Zone 3 helps you adapt to harder work than zone 3.

It burns more fat but incurs a little bit more fatigue than zone 2, as we’ve discussed.

The idea of emphasizing the highest and lowest zones is sometimes called “polarized training.”

But this advice somehow turned into a myth about people needing toavoidzone 3, which was never true.