Explanation of Training Zones and Rate of Perceived Exertion
Zone 1 is a very easy effort, probably a 4/10 on the Rate of Perceived Exertion (RPE) scale. It's so easy that it should feel almost guilt producingly easy. It’s also the intensity of an active Recovery Interval (RI) or a recovery session. You don't think you went hard enough; it didn't feel like a workout; you don't think there was any benefit because it felt too easy. If you have these types of thoughts after a Zone 1 workout, then congratulations, you are doing it right.
Zone 2 should feel pretty easy as well, at least in the beginning. But you should feel as though you have to put forth some effort if the duration lasts between two and several hours. This is your aerobic zone. You may even experience cardiac drift (which occurs when your HR increases over the duration of the workout even though the pace/effort level remains constant) towards the end of this workout. This is about a 5-6/10 on the RPE scale. You should be able to hold a conversation while speaking in full sentences for the duration of this workout.
Zone 3 is the gray zone. You aren't going easy enough to get the benefits of a nice easy effort and you aren't going hard enough to get the benefits of a hard workout. This is a 7/10 on the RPE scale, and you can talk in one to two-word phrases. There is little benefit from this type of effort level and should comprise a very small portion of your overall training volume.
Zone 4 is your threshold zone - this is your threshold pace where your legs and lungs are feeling the effort and you can't maintain this intensity for much more than an hour…which is, by definition, your threshold. You know when you are in Zone 4 when your breathing is laboured and your arms and legs are heavy. This effort is 8-9+ on the RPE scale.
Zone 5 and up are for shorter efforts and are usually 9+ to 10 on the RPE scale. This taxes your VO2max system. These efforts may last from a few seconds to five or six minutes. This zone is beneficial if you are doing a lot of racing that has hard but very short efforts, such as bike racing or racing short events on the track in running.
Consider the following analogy: a 400M race takes world class runners about 40 seconds to complete and is around 86 percent aerobic. Now, if you are running a 5K, how much of that race do you think is aerobic? It’s around 97 to 99 percent. Thus, the majority of your training should reflect this.
For the average endurance athlete, the percentage of time you should spend training in each zone is roughly as follows:
· Zone 1 and 2: 80 to 85 percent
· Zone 4: 10 to 15 percent
· Zone 5: 2 to 5 percent