Exercise scientists have developed “training zones” to help athletes and coaches understand which energy systems and muscle fibers they’re using at a given exercise intensity level.
This system divides training intensity into six zones. Zone 1 is the lowest intensity (sitting down, walking around your house, etc.), and Zone 6 is the highest intensity (all-out sprinting, deadlifting a heavy set of five, etc.).
- Zone 1
- Energy source mainly used: fat
- Zone 2
- Energy source mainly used: fat, trending into carbohydrates
- Zone 3
- Energy source mainly used: fa,t trending into carbohydrates
- Zone 4
- Energy source mainly used: carbohydrates
- Zone 5
- Energy source mainly used: carbohydrates
- Zone 6
- Energy source mainly used: carbohydrates, trending into creatine phosphate
In Zones 1 and 2, you’re using primarily fat. As you move to Zone 3, you start using carbohydrates. When you reach zone 6, you use creatine phosphate to create ATP. All cells in your body are fueled by adenosine triphosphate (ATP). When you walk, you’re using ATP. Deadlifting? Powered by ATP. Reading this article? ATP!
In Zone 2, your exercise intensity most stimulates mitochondrial function in your cells. If you were to go a bit harder, your body would start using more carbs in your cells. A lot of people miss Zone 2.
Why is Zone 2 important?
- Zone 2 helps increase the number and efficiency of mitochondria in your body. Zone 2 is the level at which you’re stimulating your mitochondria the most to create ATP. As you spend more time in Zone 2, your body creates more mitochondria to power your Zone 2 activity. The more mitochondria you have, the more you’re able to create ATP through fat oxidation.
- Zone 2 training not only increases the number of your mitochondria, but also improves their efficiency as well. The more you exercise in Zone 2, the better your body gets at burning fat for energy. The body’s inefficiency in using fat for fuel contributes to many health problems, like insulin resistance, dementia, and even cancer. If you want to move better, have more energy, and live longer, you want to incorporate zone 2 exercising.
- Zone 2 improves cardiovascular health. Besides exercising your mitochondria, Zone 2 cardio also gives your heart and blood system a workout. Your heart will get stronger, require fewer pumps to pump blood, and become more efficient. This cardiovascular fitness will result in better performance when exercising and a lower resting heart rate.
Zone 2 cardio serves as a great “active recovery exercise.”
Now you’re probably wondering, “How do I figure out my zone 2?”
You can do this in one of three ways:
- Do a max heart rate test. The best way to determine your maximum heart rate is to test it by running on a treadmill or cycling on a stationary bike. You start running and cycling, and increase the speed every 2 minutes until you can’t sustain the pace any longer. Your heart rate at that moment is your maximum heart rate.
- Estimate based on your age. If you don’t want to do a max heart rate test, you can estimate your maximum heart rate using your age. The formula is 220 minus your age.
If you’re 30 years old, your maximum heart rate would be 190 (220 – 30 = 190).
70-80% of 190 yields a Zone 2 heart rate range of 133-152, and you should aim to stay as close to 152 as possible without exceeding it.
This method isn’t very accurate. Your maximum heart rate may be higher or lower, depending on your fitness level, but this will at least give you a general idea or starting point.
- If you’re not a math person, I found a free calculator to do it for you, and it also provides the other zones. If you have the chance, try doing the actual test, and then you can plug that in and get more accurate results!
https://www.ntnu.edu/cerg/hrmax
If you use the Oura ring, you can record your workout, and it will indicate which zones you are in.
I recently purchased a Polar heart rate monitor to help track during my workouts! What I love is that you can set it so that during your workout, it will tell you when you enter the different heart rate zones!
