Heart rate zones are a percentage of a person’s maximum heart rate. They are important because they determine if some type of activity can be sustained for a short period of time or a long period of time.
An activity that causes a high heart rate, requires more resources from the body, thus we can only sustain it for a brief period of time. On the other hand, an activity that causes a low heart rate can be sustained for a long time. When a runner is doing a low heart rate run, usually the feeling is that she/he can run forever.
Importance of heart rate zones in training
New runners and athletes usually don’t have a very sharp sense of “perceived effort”, so it is common for a low-intensity workout to become a medium or intense workout just because the person is feeling good with the training and starts to speed things up. Training based on heart rate zones can help keep low-intensity workouts with a low intensity and make us push harder on high-intensity workouts.
Have you ever done interval training but didn’t see much results afterward? Maybe it was because you didn’t elevate your heart rate enough.
Have you ever felt tired or felt some pain after an easy run?
Maybe it was because your easy run was not so easy, and your heart rate was higher than it should be.
By controlling your heart rate, you can have a reliable way to control the different intensities of your training plan workouts.
Heart rate zones
There are 5 zones, expressed by a percentage of your maximum heart rate – MHR.
To measure the maximum heart rate you can use this calculator https://www.ntnu.edu/cerg/hrmax . It will give you a rough estimation, but keep in mind that for accurate results a lab test is the best. However, lab tests are more advised for experienced athletes due to the costs and setup needed.
Zone 1 – 50%-60% MHR
Usually, athletes stay in this zone during a warmup or a light activity like walking.
Zone 2 – 60%-70% MHR
In this zone, the body uses oxygen and body fat to generate energy to move – Aerobic activity. It’s possible to sustain activities in this zone for a long time while maintaining easy breathing. This is usually called the base heart rate zone and is where easy runs and some active recovery workouts are done.
Running in this zone improves overall endurance and is essential in a well-structured training program.
Zone 3 – 70%-80% MHR
For beginner and intermediate athletes, zone 3 is where the lactate threshold is. Usually, this is where tempo runs and threshold runs are made.
But be careful, this is a bit of a grey area. Sometimes athletes are meant to run easy runs at Zone 1 or 2, but end up running in Zone 3, which neglects the great effects of a slow easy run in the training plan, and might cause performance plateaus over time.
This area is best used close to a race or when you need to prepare mentally for the challenges of running faster for longer.
Zone 4 – 80%-90% MHR
In this zone, things start to get hard. The body starts to work aerobically –consuming carbohydrates for energy instead of oxygen and fat – which is a source of energy that does not last long, breathing will be harder to control, and on top of that, at this zone is where the lactate acid usually starts to build up, causing the typical burning feeling in your legs and a sensation of increased fatigue sometime after entering this zone.
Training in this zone will improve an athlete’s maximum potential, helps achieve better running efficiency, more leg power, and tolerance to higher paces for more time.
Zone 5 – 90%-100% MHR
Working out in this zone is only possible for brief periods of time. The body is not able to clear the lactic acid and other byproducts fast enough, the heart is not able to pump blood faster into the muscles to bring them the demanding energy needs.
This is the danger zone. These levels should only be reached at high-intensity workouts like interval training sessions, or during competitions by experienced athletes because they are not sustainable for longer periods due to the hard body demands. It can be dangerous for the heart to push it too hard for a long time since it is working at its maximum capacity.
Which zones should I train?
A good training plan involves all zones. In order to run faster for longer, an athlete cannot just be doing intervals and making all runs zone 4 or 5. In fact, a high percentage of the runs in a training plan is usually done in zone 1 or 2, because that is where the base is built and where a safe environment exists for muscles, joints, and tendons to adapt to the running demands.
A common rule is the 80-20 rule, which says that 80% of a training plan should be done in low-intensity zones (1 and 2), and only 20% is for high-intensity zones.
At the beginning of my running journey, I made the mistake of making all my runs as hard as possible, which made me reach a plateau very quickly. Only when I started using easy runs and the 80-20 rule I could see improvements. You can read more about that story in this article How to start running – beginners guide .
