THE FIVE CARDIO ZONES & HOW TO EFFECTIVELY USE THEM
Highway to the…Cardio Zone? The Heart Rate Target Zone system of categorizing exercise has caught quite a bit of steam across the ‘gram and in fitness circles of all types. What you’ve probably heard most is the term “Zone 2 Cardio,” and if you’re anything like me, you've most likely asked yourself - “well what about the other zones?” Well, you’re in luck because today we’re talking about what the zones are and how to use them.
You may be surprised to hear that you probably already know more about the 5 heart rate target zones or “cardio zones” than you think. If you’ve ever been late for a plane and had to sprint through the airport with all your luggage to make the flight and you feel your heart pounding as you finally plop down in your seat, you’ve been in the higher end of the cardio zones. You see, there is a direct, linear relationship between exercise intensity and heart rate. In other words - the harder you exercise, the higher your heart rate is (which most of us know intuitively!). The 5 numbered zones are simply a “framework” to categorize and understand the purpose of different training intensities as well as how they impact things like performance, health, and longevity.
BREAKING DOWN THE ZONES
Let’s take a quick look at what the 5 zones are first:
ZONE 1: 50-60% HEART RATE (HR) MAX
Often referred to as the recovery zone, this is a very light intensity that you should be able to sustain for hours and hours while also being able to carry on a conversation simultaneously. Many of our activities of daily living fall into this category and we should be spending lots of time in Zone 1 daily.
Examples: walking, gardening, cleaning the house, grocery shopping, leisurely recreational activities.
RPE (rate of perceived exertion): 5-6
ZONE 2: 60-70% HR MAX
This is the lowest intensity that we’d consider to be metabolic “training”. It is considered aerobic training because the body is able to use oxygen from breath to fuel exercise. This is the intensity we could spend a long time at. The limiting factor on Zone 2 cardio is usually boredom and/or having a life outside of doing Zone 2 cardio - but your body should be able to sustain this pace for 2-3 hours if it needed to.
Examples include hiking, rucking, lower intensity running, cycling, swimming, rowing, and some recreational sports.
There are so many benefits to doing zone 2 cardio regularly - better recovery, greater longevity, mental health benefits, better aerobic capacity, increased fat metabolism, lower resting heart rate, increased HRV, and greater parasympathetic nervous system activity. Research suggests that most people would benefit from getting at least 1-3 hours of Zone 2 cardio in per week.
RPE: 6-7
ZONE 3: 70-80% HR MAX
This is where we are moving from aerobic to anaerobic exercise, meaning instead of using oxygen directly from the breath, we are using energy stored within the muscle cell to contract our muscles - and making that transition can be uncomfortable physically. Zone 3 is approaching the lactate threshold which means the body is just on the verge of not being able to clear metabolic byproducts, and we may start to feel the buildup of those byproducts as a “burning’ sensation. This is a pace we could sustain for shorter periods, intervals, tempo work, or “race pace” training.
**Note: This is often where many exercisers will end up spending lots of time if they’re not paying attention to their HR. The casual exerciser may end up in Zone 3 if they decide to go for a run after a period of not training. It’s often viewed as an undesirable “gray zone” from a training standpoint because it isn’t great for improving endurance (zone 2 is much more effective), OR speed (Zone 4 & 5 are better here), and can be very taxing physically and from a nervous system standpoint. Most people who want to live a healthy and active lifestyle would have better benefits from spending more time in Zone 2 and less in Zone 3.
RPE: 7-8
ZONE 4: 80-90% HR MAX
Zone 4 is where intensity FEELS very high - an 8-9 / 10 on the RPE scale. This pace is very difficult to sustain for over a minute. At this intensity, we are definitely in the anaerobic zone. Training in this zone will help the body to be able to tolerate and buffer more lactate, making us more capable of sustaining faster / more intense efforts for longer.
Think hard interval training of various modalities: running, cycling, swimming, rowing.
ZONE 5: 90-100% HR MAX
This is the most intense level we can get to. This is where the 100m dash lives - very high intensity and very short duration. Highly trained athletes may be able to maintain this level for 30-40 seconds - and even for them it would feel VERY hard.
Though it’s important to spend some training time here, this zone shouldn’t be used all the time - shoot for about 2-10% of your training in zone 5. It’s extremely hard to recover from from a nervous system standpoint.
HOW TO ACTUALLY USE THIS INFORMATION:
So now that we know what the Zones are, how do we make sure we are utilizing them effectively? We all have different maximum heart rates due to differences is fitness level, age, injury status, sex, and other factors. Most of us don’t actually know what our max HR is because it requires some specific testing to get an exact number. That said, we do a few good ways to estimate max HR so that we can figure out our own personal zone percentages. Things to consider:
AGE: Most HR calculations use some variation of an age based formula. The most common formula to estimate your max HR is: Max Heart Rate = 220 - (minus) Your Age. This may not be the most accurate, but it can surely be a helpful starting point.
FITNESS LEVEL: If you are a trained athlete or have been exercising regularly for a consistent amount of time, you can add 5bpm to your estimated HR max. On the other hand, if you haven’t been training consistently or are coming back from an injury, you can subtract 5bpm from your HR max.
RPE (RATE OF PERCEIVED EXERTION): RPE is a great way to gauge intensity and research suggests that it is a fairly accurate measure for trained individuals. It’s a scale from 1-10 with 1 being extremely easy and 10 being the most challenging effort you can muster.
From a practical standpoint - what do we do with all this information? It’s nice to know the 5 zones, but what do they do for us? There is so much individual variation to consider in this question. I find it helpful to reflect on your specific goals to answer this question.
For the general population exerciser who is interested in feeling good, living a long and healthy life, having energy and reducing stress:
75-80% of our exercise would be well spent in the lower zones 1&2, while moving up into the higher zones for up to 20% of training would be enough to improve anaerobic fitness while still being able to recover well.
The CDC recommends 150 minutes of moderate intensity exercise (Zones 1&2) or 75 minutes of vigorous activity (Zones 3-5) weekly, alongside 2 days of strength training for adults
For athletes who are looking to improve performance, more time will need to be spent in the higher HR zones. This will vary depending on what events an athlete is training for. For example, a marathon runner might spend much more time in Zone 3 as opposed to a 100m sprinter, who might spend a significant amount of time in Zones 4, 5, and 1.
Another key consideration is: what mode of exercise is the most enjoyable for you? At the end of the day, we tend to be most consistent when we enjoy what we’re doing. Do what you love and look for ways to balance out with some exercise from the other end of the spectrum, too. So, if you like crushing MetCons and getting after it in the CrossFit gym - great! Just make sure you’re spending time recovering in Zone 1 & 2 also. If you like long hikes and afternoons in the garden, make sure you’re getting a few minutes a week at higher intensities.
WHATEVER YOU DO, HAVE FUN WITH IT!
UNTIL NEXT TIME - COACH SARAH
