The idea of training zones was established in the cycling community largely due to the book Training and Racing with a Power Meter. It was originally published in 2006 by Hunter Allen and Andrew Coggan. Training zones have since taken the cycling world by storm as an effective way to describe interval intensity and allow coaches to more easily and effectively prescribe workouts to their athletes. Let’s go over the different zones and at the end discuss how these zones can help you improve as a cyclist.
Cycling Training Zones Basics
The most common method of describing training zones is through the seven zone system established by Allen and Coggan specifically for cycling. There are a few other zones models from other researchers, generally with more zones. The seven zones described here are the most common and, frankly, the easiest to follow. All of these zones are based on a percentage of your threshold power or heart rate. Threshold is normally used to describe the power a cyclist can maintain for about an hour. Threshold heart rate is the average heart rate of that effort. The easiest way to find out your threshold is to do a 20 minute all out effort on a flat or uphill road with no stops and take the average power of that effort and multiply it by 0.95. This gives an approximate power for your threshold and can be used to build the other zones.
The Training Zones
Zone 1: Active Recovery
The first zone is called Active Recovery and is described as approximately 50% of your threshold power or about 65% of your threshold heart rate. This zone is used for active recovery rides, ‘recovery days’, and for recovery between efforts. This zone facilitates blood flow and muscle recovery. For an active recovery day, a rider would simply go for a one hour ride at 50% of their threshold, normally about 140-150w, making sure their power doesn’t spike up into other zones during the ride.
A rider could be prescribed active recovery between sets of high intensity intervals. The recovery effort is used to help move lactic acid out of the muscles. It also keeps the legs from locking up after the effort. It has been shown that active recovery does a better job than no movement at preparing an athlete for the following interval. If you are doing intervals on a climb, try to spin as much as possible on the descent before your next interval.
I want to emphasize how SLOW this zone is. For active recovery days, you should feel like the grandma next door could out-ride you. Emphasize keeping the gears light and cadence high maximize movement of the muscles and improve blood flow. Think of active recovery as a little massage for your muscles.
Zone 2: Endurance
Zone 2 is the bread and butter of most professional road cyclists. Commonly referred to as ‘endurance pace’, a rider is in Zone 2 when their power is about 70-75% of their threshold or about 70-80% of their threshold heart rate. The purpose of the endurance zone is to build the aerobic and endurance capacity of the body without excessive fatigue. Other zones at higher intensities can also build aerobic capacity, but they also tend to fatigue the muscles significantly. As a result, less total time can be spent in those zones.
Most athletes can withstand A LOT of time in endurance zone. This allows for more total aerobic adaptations than someone who spends more time at higher intensities. The main benefits of endurance zone training are improvements in stroke volume (the amount of blood each beat pushes), mitochondrial density (the amount of force producing units in your muscle cells), and improved blood flow through your muscles for increased utilization of oxygen for power production.
Training Zone 2
Base training involves spending lots of time in this Endurance zone. The importance of working out in this zone cannot be understated. A rider who effectively trains their endurance zone through base will have a leg up on their competition in aerobic efforts. Of the three energy systems, the Aerobic system is used almost exclusively in any effort over 5 minutes. Failure to effectively build up the Aerobic energy system is the first step to getting dropped in your next race or group ride. Make the Endurance zone your friend!
Endurance rides will normally be about 2 hours to start, with increases in total time as the athlete develops. Professional cyclists will do endurance rides for 6 hours at a time, but their races are also 6-7 hours. A rider generally will not do endurance rides longer than their longest event. Fueling is important for endurance zone training. Continuing to eat ~60g of carbs per hour after the first hour throughout the workout is highly recommended.
Zone 3: Tempo
Tempo is a bit of a weird zone. It’s harder than endurance, but it’s not too hard. Tempo is described as 75-90% of your threshold power or 85-95% of threshold heart rate. This is the first zone where you start to feel like you are trying to make an effort. Tempo efforts are still aerobic in nature. Riders will generally train in this zone for 20 minutes up to one hour or more.
Theoretically, a tempo effort can be maintained indefinitely as long as the body has sufficient energy (food) and hydration. The difference between tempo and endurance is that tempo requires you to actively think about the effort. Your body will naturally start to ease off the power back to endurance pace. Unlike endurance, there is a significant muscular load in the effort and riders should expect some soreness following workouts in this zone.
Training Zone 3
Coaches tend to neglect this zone in training prescriptions. They find it hard to show the athlete the result of their time. It’s not quite low intensity enough to do consistently day over day, week over week. It’s also not high enough intensity to see improvements in high-intensity metrics. Zone 3 can be seen as a ‘time-crunched zone 2’. The adaptations to the body from this zone are similar to the adaptations from the endurance zone, but less time is needed to achieve those changes. Tempo workouts where 1-2 hours is spent at tempo in chunks of at least 15 minutes can be a good exchange for a 4 hour endurance ride. This is especially true for a cyclists with less time to train because the concern of excessively fatigued muscles is lower.
The other advantage of tempo workouts is that, well…, you get better a tempo efforts. Road races spend most of their time in the tempo zone. The barrier for entry in P12 races in California is the ability to hold 205-225w for 4 hours. In these events a rider needs to feel comfortable hold tempo for a loooong time. Specific training in this zone can help athletes make it to the end of a long race in the front group. From there they are set up for an opportunity to sprint or attack for a podium place. As a road racer, tempo is one of my favorite zones; I have learned to love the zone that keeps me from getting dropped.
Zone 4: Threshold
We already spoke a bit about threshold at the top of the article, but let’s do a full dive into this zone. Threshold is the zone around the power you can hold for an hour. Specifically the threshold zone is about 95-105% of your threshold power or about 98-106% of your threshold heart rate. Threshold can be thought of as the hardest we can go sustainably. Every zone about this blows up in our face eventually as we slump over our bikes at the end of the effort.
So, what is our threshold really? From a physiology perspective, our threshold is the crossover point where lactic acid accumulates and can’t be removed quickly enough. When we do an aerobic effort, such as a tempo effort, there is minimal lactic acid production. As the intensity of our efforts increase, the ability for our body to provide the energy we need with only our Aerobic system diminishes. As a result, we start to use our Anaerobic system. This system creates lactic acid as a byproduct, which our body attempts to filter out to continue to operate. Eventually our intensity is too high to filter out all of the lactic acid and we collapse from muscular exhaustion.
There is some point where our Aerobic energy system is maxed out and our Anaerobic system is producing lactic acid where the amount of lactic acid produced is the same as the amount being filtered out. This point is our threshold. The key here is that our threshold is determined by the combination of the capacity of our Aerobic system AND the capacity of our body to remove lactic acid as our Anaerobic system works.
Training Zone 4
Training at threshold has one big advantage: it maximally utilizes the Aerobic system. This training effect causes unique adaptations that allow us to increase our aerobic capacity in future workouts and events. Threshold workouts can be very damaging to the body. So be careful! Efforts can be anywhere from 8 to 30 minutes, but the most common threshold workout being 2x20mins at 95% of threshold. Some athletes do almost exclusively this workout leading up to the race season and they get killer strong! With that being said, doing too much threshold can burn out your legs from the fatigue. Don’t forget to train the other zones as well; there are unique adaptations from them as well.
Zone 5: VO2max
The term VO2max generally refers to the maximal volume of oxygen uptake by an athlete. A common exercise science lab test is to hook a tube and mask to an athlete on a bike. A researcher measures their gas exchange through the tube and mask. With that information, sports scientists can graph their oxygen utilization, a de facto measure of the work done by their aerobic system. As intensity increases, this oxygen utilization rate flattens and the athlete no longer increases their oxygen utilization. This point is their VO2max. The VO2max zone is somewhere around 113-120% of a rider’s threshold power. Heart rate cannot accurately be used to determine if a rider is in their VO2max zone. This is due to the lag time between starting an effort and the athlete’s heart rate response.
VO2max efforts are anaerobic in nature. The point is that we are going beyond the aerobic capacity and intentionally accumulating lactic acid in the muscles. The purpose of workouts in this zone is to improve our body’s ability to filter lactic acid out of the muscles at a higher rate. Remember, threshold has an aerobic and anaerobic portion. Improving the body’s ability to remove lactic acid can show improvements at threshold. VO2max intervals can also help the body withstand the fatigue associated with high intensity efforts. In your next group ride or road race, if you get popped on a 4 minute climb, maybe you should be putting a few more VO2max intervals in your workout calendar.
Training Zone 5
VO2max workouts are generally sets of intervals with specified work and rest periods. One common interval set is 6x4min in VO2max zone. Some athletes respond to VO2max intervals easily and will find themselves at the top of the zone (~120%+ of their threshold power) while others will struggle to hit the bottom of the zone. Another good interval set is something like 4x8min at 40 seconds on, 20 seconds off. This interval can be less fatiguing for some, but provides the same total time in zone as the 6x4min intervals. It has been shown that the greatest increase in VO2max comes from workouts that maximize the total time spent in the zone, but how the time in zone is chopped up into pieces is less significant. It usually comes down to rider preference if they want to do many small efforts or a few big ones.
Zone 6: Anaerobic Capacity
If you remember from the energy systems article, the Anaerobic energy system is the main contributor to power production. It’s used anywhere in the range of 15 seconds to about 2 minutes and produces energy without oxygen. This system is great for punchy efforts to get rid of opponents or tackle a short climb quickly. It’s horribly inefficient, and guzzles through carbohydrates. Anaerobic capacity workouts are also very damaging to the body, they are all out efforts in the range of 45-75 seconds done with moderate rest in an attempt to max out the Anaerobic energy system in hopes of increasing the capacity of that system.
I don’t have much to say on this zone, I hate it. It hurts so much and these efforts are quite violent in nature. Make sure you have a clear road to complete them on and go full gas to blow out the system. Follow up these efforts with plenty of rest as your muscles will likely be pretty toast. Anaerobic capacity workouts are normally prescribed only a few weeks leading up to a key race because adaptations to the Anaerobic system decay in a short window.
Zone 7: Neuromuscular Power
The last zone is the sprint zone. This zone is anything under 15 seconds. There isn’t much to say about this zone either, except that it leans on the Sprint energy system almost exclusively. Workouts to train neuromuscular power are simple. Do 6-20 all out sprint efforts in the same workout with 2-3 minutes in between and go home.
The goal here is the improve the capacity of the Sprint system and over time the body’s ability to produce sprint power will increase. Efforts should really be done out of the saddle if you are a road racer or in the saddle if you are a track rider. These efforts can also help improve the explosivity of your muscles and can be a good way to train your cadence up to higher numbers. Try a few sprint workouts where your cadence at the end of the sprint is 150-170rpm.
Conclusion – Do Cycling Training Zones Matter?
I didn’t say this earlier on, but the training zones for cycling are kind of bogus. Ok, maybe they aren’t bogus, but they also aren’t the end all be all.
The truth of the matter is that a lot of us won’t fit into the narrow windows provided by Allen and Coggan. There is a lot of variability in the capacity of different rider’s and their ability to withstand different efforts. For example, despite being a good road racer, I always struggled to be in the endurance zone on my long rides, typically dropping to the bottom of the zone. At the same time, I always hit huge VO2max numbers relative to the prescribed zone. It could be because my threshold was too low, or needed improvement, but that would only make it harder to stay in the endurance zone for long rides!
The inherent variability in humans makes this narrow view of physiology ineffective for many athletes. With that being said, there is still much to learn about your cycling from the idea of training zones. Long slow rides have unique and important adaptations for our hearts and muscles. VO2max efforts maximally utilize the Aerobic system and help train our resistance to muscular fatigue at high intensities. Threshold efforts effectively train the capacity of our Aerobic system. These ideas are the fundamentals of training for cycling. So buck the exact zones and the percents and the numbers and the charts. Get into the spirit of the training zones. We have a lot of different areas to work on in cycling, let’s use the concept of training zones to lead us in the right direction.
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