12 Facts About the Five Heart Rate Zones

There are some special characteristics of the five heart zones that make them what they are. The key fact is that a different thing happens in each of  the different heart zones. This means that you have to train in different zones to get each of the different benefits.

Fact #1. Zones have size.
The size of each zone is a 10% range of your true Max HR. The size of the zone in number of beats depends on how high your true Max HR is. Given a 200 bpm Max HR (which is very convenient for multiplying), each of the five zones would be 10% of 200, or 20 beats wide. Most zones for most people range from 15 to 20 beats in size; this is big enough to allow for some "wiggle room" when you are working out, but small enough to be on target for your particular training goal(s).
 
Fact # 2. Zones have structure.
A zone may be viewed as being made up of two different parts: its top and bottom halves. In other words, inside every zone is an upper and and a lower zone. So, while the whole Aerobic zone may be from 70% to 80% of your Max HR, the lower half of the zone is 70%-75% (or 140-150 bpm in our 200 bpm Max HR
example), and the upper Aerobic zone is 75%-80% (or 150-160 bpm in this case). It's just a way to subdivide a medium-sized window into two smaller, even more focused parts.

Fact #3. Zones have dividing lines.
The upper and lower limits of each zone coincide with the floor and ceiling of its bordering zones. The floor or bottom of the 23 Aerobic zone, for example, is 70% of your Max HR. This floor, or lower limit is that heart rate where you first break into this zone. Seventy percent of your Max HR also happens to be where the Fat Burning zone ends. The Aerobic zone ceiling, 80% Max HR, is the line at the very top or threshold of the zone. At this point you are passing through the Aerobic zone ceiling into the floor of the next
higher and more intense zone, the Anaerobic zone.

Fact #4. Zone names correspond with their benefits.
Each zone has a specific benefit that comes from the physiological activities that happen when you exercise within that heart rate zone. For example, the 21 Healthy Heart zone is exactly that, the range of heart rates where most individuals realize the most cardiovascular benefits, leading to improved heart and lung function.

Fact #5. Zones have numbers.
There are certain specific and measurable events that are so exact that they're represented by a single heartbeat value called a heart rate numbers. You may already know a few of them: the maximum heart rate number and resting heart rate number are specific heart rate numbers that are located in relationship to (inside or on the dividing lines of) the zones.  For example, the diagram below is the location of your Max HR on the ceiling of Zone 5.


THE DIAGRAM OF ONE HEART ZONE: Redline Zone

200 Beats Per Minute =  100% of your Max HR Ceiling
 
Redline Zone =  90% -100% of your Max HR  or 180 - 200 BPM
* Midpoint Heart Rate

Fact #6. Zones are a subset of the wellness continuum.
The wellness continuum consists of three areas of physical well-being--health, fitness, and performance--and we need to keep in mind that we're not all going to have our goals in the same areas. This is why your friend, who's a veteran marathoner, might complain about what kind of "shape" he or she is in, while you would kill to look the way they do and be so fit and healthy. The health area covers those training zones that promote health but don't primarily improve physical fitness and certainly not performance. To measure improvements in health, we seek positive changes in blood pressure, body fat, cholesterol, etc. To measure improvements in fitness, however, it's positive changes in oxygen utilization, lactate concentrations and heart rate points we're looking for. And, to measure improvements in performance, positive changes in completion times, accuracy of movement skill, mental attitude, and other indices are used.

The Wellness Continuum and the Five Heart Zones
Zone Name Percentage of Max HR Wellness Continuum
Perceived Exertion Difficulty

Z1 Healthy Heart Zone 50%-60% Health Zone
2-5 ( perceived exertion ) 
Z2 Temperate Zone 60%-70%
4-5  ( perceived exertion )
Z3 Aerobic Zone 70%-80% Fitness Zone
5-7  ( perceived exertion )
Z4 Threshold Zone 80%-90%
7-9  ( perceived exertion )
Z5 Redline Zone 90%-100% Performance Zone
9-10 ( perceived exertion )

Fact # 7. Zones use time, not distance, as their measurement tool.
That is, the amount of time you spend in the zone is the way you measure your workout, not in miles run, or the number of strokes per minute cycled or rowed. This measurement is called "time in zone" and is measured in the minutes that you spend in each zone. For example, one day you decide to run for 30 minutes in the Aerobic zone; the following day you might choose to walk for 50 minutes in your Fat Burning zone. Varying your workouts, both in activity and zone, allows you to get multiple benefits from your training.

Fact # 8. Zones have specific numerical values, they are weighted.
When we talk about "exercise by the numbers," that means doing workouts based on the specific numbers that make up your exact zones. For example, if your true, tested Max HR is 200 beats per minute, and you wanted a high fat-burning day as a percent of your fuels burned, you would calibrate that workout to be in Zone1-Z3. If you really wanted to fine-tune your training, you might choose to narrow the window to Zone 3. Use the following chart to determine the specific numerical values for your five zones.

Fact #9. Higher zones require less time in zone than lower zones.
At the lower zones--or "cruise" zones as they are sometimes called--you can train in zone for longer periods of time. But, as you move up to higher intensity zones, you need to decrease the amount of time that you spend in that zone, particularly in the top two, the Anaerobic and Redline zones. This simply makes sense--you can walk farther than you can sprint, and overdoing it is nearly a guarantee of injuries or burnout.

Fact # 10. Zones are relative.
Your five heart rate zones are specific to your maximum heart rate, not anybody else's. With two runners, each maintaining a heart rate of 160 bpm, one might well be in their Z4 Threshold Zone and the other may be in their Z2 Temperate Zone. It's all relative.

Fact #11. Zones are metabolic, calorie burning zones.
Each heart zone burns a different number of calories per minute based on how fit you are.
Zone 5 20+ calories per minute
Zone 4  17-20 calories per minute
Zone 3   12-17 calories per minute
Zone 2   7-12 calories per minute
Zone 1 3-7 calories per minute

Fact #12. Fat is burned differently in each of the heart zones.
You'll burn a different ratio of fat to carbohydrates in each of the heart zones. Remember, once you've crossed over the exercise intensity threshold called "anaerobic threshold" you are burning no additional fat, though you still burn fat. That's because oxygen has to be present for fat to burn. If there's no additional oxygen present, there's no additional fat burned.

One of the foundation principles of Heart Zone Training is that we need to train in different heart zones to get different benefits. Here are 12 facts that make that principle clear. There is no one "training zone". There is no one "target zone". Those are old training concepts that have been shown not to fit with the way the body really trains. In fact, there are multiple zones that provide multiple and varied benefits. Train in the zones that most fit your goals: health, fitness or performance.