Cardio in Zone 3 Is Just As Good As Cardio in Zone 2, so Please Relax.
Training in heart rate zone 2 has its benefits , and you’ve probably heard all about them. So what happens when your heart rate hits zone 3 during a run or when you do cardio at the gym? Surprise: you don’t lose the benefits of training in zone 2. In fact, zone 3 is probably just as good for you, maybe even better.
Remember, the reason people rave about Zone 2 workouts is because they build an aerobic base and burn calories without causing much fatigue. Guess what zone 3 training also does? Yes, it builds your aerobic base, burns even more calories, and generally causes only slightly more fatigue than zone 2. So why don’t we all train more in zone 3?
Influencers and heart rate monitors have ruined “light” cardio
There are reasons to run (or do cardio) at a lower intensity, and there are also reasons to use a higher intensity. Before heart rate monitors became widespread, you had to judge “ease” on your own or by comparing your running speed to what you knew you could do in a race. For non-athletes, we conducted a “speaking test.” If you could carry on a conversation while running, you knew you were moving at an easy and steady pace.
But when everyone has a watch that tells them their heart rate, suddenly we’re looking at specific numbers and our watches color code the numbers so you know when you’re in zone 2 rather than zone 3. Is your heart racing? You’re out of your zone. Straight to jail.
But the reality is that your body doesn’t get a dramatically different workout at 153 bpm than at 152. There’s probably not much difference between, say, 145 and 155 bpm, as long as they’re both within normal limits. this conversational level of effort.
The zones are not real
Heart rate zones are compiled. I guess it’s a fun idea, but it’s not based on any scientific findings that say we get these different benefits at 60-70% of our maximum heart rate and these different benefits at 71-80%. If you’re not sure, just look at how different gadgets and apps define zones differently . Your “zone 2” might be 60-70% on the Apple Watch and 65-75% on the Peloton. The zones are made up, okay?
Studies on the benefits of exercise do not use heart rate zones, at least not of this type. They can measure intensity in a few different ways, including whether you’re above or below your ventilation threshold (essentially whether you can talk while exercising) or lactate threshold (measured using blood chemistry, but essentially , this is the maximum force you can withstand). for a long time). Sometimes they measure METs, which show how much energy you expend at work. They sometimes send participants home with recommendations based on heart rate, but these tend to be based on the measurements above rather than standard heart rate zones.
The conversation pace includes zone 2 and most of zone 3.
So let’s take a closer look at the idea of a “speaking test” or “speaking pace.” Recommendations for maintaining light cardio at a gentle pace are based on a scientific concept: respiratory threshold.
Imagine starting by walking and increasing your speed a little every minute or so. As you work harder, you will reach a point where you will not be able to breathe properly. Your breathing becomes a little ragged, your sentences choppy. This point is your respiratory threshold, or VT (sometimes called VT1).
When athletes or coaches talk about easy tempo or easy effort, they usually want your VT to be lower than yours. The way people talk about zone 2, you would think that VT occurs at the top of zone 2. But no – the conversation rate is closer to 80%, which is the top of zone 3 . For example, here’s a study of recreational runners that found that VT1 averaged 78% of runners’ maximum heart rate . And they tested runners’ maximum heart rates rather than using a formula based on age. (Never trust default formulas.)
So if you’re trying to train at an easy pace or using the 80/20 rule to have 80% of your runs be easy , you can do those easy runs or cardio workouts in zones 2 and 3 rather than just zone 3.
Zone 3 is still aerobic and still easy.
Now that we understand that the distinction between zone 2 and zone 3 is arbitrary, it makes sense to consider zones 2 and 3 (or even zones 1 to 3) as a continuum. At the lower end, you’ll run or pedal slower, burn fewer calories, and feel like you’re doing almost no work. (Hello, cozy cardio !)
At the higher level, which is the top of zone 3, you’re still doing more aerobic work, still benefiting your mitochondria and capillaries and everything else, but you’re doing it in less time. If you’re interested in burning calories per hour, zone 3 is more efficient.
Cyclists sometimes refer to training in this range as the “sweet spot.” This gives you some of the benefits of harder workouts without causing excessive fatigue. For runners, Zone 3 may include some of your tempo runs, some of your race pace runs, and some of your faster “easy” runs.
So what’s the point of zone 2 if all its benefits can be obtained in zone 3? It depends on the overall picture of your training. If you train a lot, you’ll probably want to keep some of your training in zone 2, just to save some energy while you put more miles on your feet. But if you run, say, three times a week, it’s unlikely that those couple of runs will tire you out much, even if you run them all in zone 3.
In any case, you should not attach too much importance to your heart rate.
Let’s get back to my little grievance about heart rate monitors. (This is a grudge born of love; I track my heart rate when I run and find it helpful in many ways.)
Your heart rate tracks more than just your training efforts; it also responds to summer heat, giving you better performance for the same effort . It may also show higher numbers if you are more fatigued, it will show higher numbers at the end of a run compared to the beginning, and it may show higher numbers if you are a little dehydrated. When you’re running a race, you may find that your heart rate is higher than expected at the start, simply because you’re a little nervous.
And here the question arises whether your zones are set correctly (even knowing that yes, their boundaries are fictitious). If you’ve never competed in a race or hill sprint series, your watch may have never seen your maximum heart rate. So if it says your maximum should be 184 because you are 36 years old, those are just numbers from a formula. This makes the same sense as buying shoes based on the average shoe size for a 5’6″ woman, rather than measuring your feet (or trying on shoes). If you go out for an easy run and find that your heart rate is in “zone 5” the entire time, I guarantee you that it is not your zone 5.
So if your heart rate falls into zone 3 during a “zone 2” training run, that may or may not be accurate. But even if that’s the case, if you can still breathe and speak more or less normally, you’ll get a ton of benefits from zone 3 cardio.