By Martin Sigrist
There are a number of reasons for riding a bike. Often these include wanting to get fitter and/or taking part in competitive events (even if the challenge is just to finish). If this is the case some of the following may sound familiar:
“I’ve just bought a bicycle, how should I train?”
“I’ve been riding several years. Back when I started I set a new Strava PB on most every ride. Now my times are just getting worse. Can I get out of this rut or am I just condemned to get slower and slower the older I get.”
“I’ve entered the Etape Du Tour. The problem is that it includes several long mountain climbs and I’ve never gone more than a few feet above sea level as it’s pan flat for miles in every direction. How can I best prepare, what’s a realistic finish target and how should I pace myself during the event itself?”
“I want to go faster on my bike split in triathlon. Is it worth me spending money to get a new frame?”
“I’m faster than everyone nearby? Do I have the talent to make the podium at regional/national junior/senior/masters/pro level)”
“I can only spend a few hours each week training. What’s the best way to spend my time?”
“I’m snowed in all winter, can I still train effectively?”
“I’ve entered some races but never finished anywhere near the top 10. Am I doing something wrong and if so how can I get better?”
Training with a power meter can help answer all the above questions and a lot more.
This first article will deal with power zones. These are fundamental building blocks on which full power based training programs are built. By the end of this three article series you should know what zones are, how to determine your personal “power profile” and how to use this information to put together plans to train for and take part in the challenges you have set for yourself. No prior knowledge of power meters or formalized training is required. The only assumptions made are that you have access to a power meter and are motivated to improve your performance.
What are Power Zones?
Some fundamental rules of cycling will be familiar to all riders of whatever ability:
- Not all efforts feel the same.
An all out sprint feels different from a 10 mile time trial which in turn feels different from riding a road race with lots of short hills which in turn feels different to century Gran Fondo with multiple epic climbs which in turn feels different to an ultra endurance event lasting several days.
- Every effort has its limit
Efforts may vary but one thing is consistent. The first few seconds, minutes or even hours (depending on duration) may not feel that hard. But if you keep pushing hard at that pace then at some point something will give and your legs will stop working. You may not come to a dead halt but you will experience a sharp drop in your performance and it will take a while before you feel ready to pick up the gauntlet and try again.
- The harder the effort the quicker you hit the limit
If you go very quickly than you will hit your limit very quickly, after just a few seconds. If you go very slow the limit may not come for days. In between the margins can be small. You can attack a small hill confident that you can reach the top only to crack when you turn a corner and find that it is not the summit but the half way point.
It is as if, like a car, your body has a number of “gears”. The higher the gear then the faster you go, but at the cost of drastically reducing the time for which you can maintain your speed.
The reason for this occurring is that the human body has adapted to produce energy in a number of different ways, each suited to deal with a different survival challenge. At one extreme is the requirement to instantly move very quickly to catch prey or avoid a predator, at the other is the need to endure long months of winter with famine knocking at the door. In between is the mix of physical activities which our hunter-gatherer ancestors had to perform every day.
Taking the car analogy a bit further helps with understanding this. Your body is a complex hybrid, with multiple types of engine. Your sprint is like an ethanol fueled dragster, your ultra pace like a diesel truck with a specially extended fuel tank. Filling the middle is a gasoline fueled car whose owner has fitted a turbo charger which quickly adds a lot more power for overtaking. Unfortunately, they did not alter anything else. So thrill of the turbo kicking in always risks being followed by the gargle of the fuel tank running dry or, worse, the engine exploding as the cooling system cannot cope.
Sports science uses the term “zone” to capture this concept and turn it into something that can be used in training.
Typically a zone will consist of two elements:
- A combination of effort at a given intensity for a duration. (so your “sprint” zone might be 10/10 intensity for 10 seconds).
- An underlying physiological “engine” that is especially important for this zone (so your “sprint” zone is linked to your “fast twitch” muscles)
The duration will be a range and not fixed in stone. They will vary between individuals and also for an individual over the course of a training period according to how they train. Indeed extending the time you can spend in a zone is often a training objective, though maybe at the cost of affecting other zones.
Zones provide a language to help athletes understand their current fitness level, to learn from/compare themselves with others and plan to improve in the areas most important to them.
As an example: say a racer has an issue with being dropped on hills. Just telling a coach this and expecting them to fix it hits the problem that hills can be very different from each other. The circumstances of racing can make these differences even larger. Zones can cut through this ambiguity and give this racer a means to pinpoint where they are weaker than their competition and suggest what they can do about it. Exactly how will become clearer once we have an actual example of zones to base discussion on.
Coggan Classic Power Zones
There are a number of different ways to define zones. The “Coggan Classic” system will be used for this article and is shown below. (It is named after Dr Andrew Coggan who, along with Hunter Allen, wrote the seminal book “Training + Racing with a Power Meter”. First published in 2006 and now in its third edition this introduced many of the key concepts about power based training that are now in widespread use. It remains essential reading for anyone who wants more in depth information about the subject.)
The zones are numbered so that the higher the number the harder the effort and shorter the duration. While other systems will differ in terms of the number and naming of their zones they will mostly follow this convention.
Each zone has an event example which describes the predominant character of the zone. (Though often things may be more complex. So a long road race will overall be in zone 2 but may well include other zones as well, say zone 5 if there are short hills and almost certainly some zone 6 and 7 at the finish.)
The last two columns provide some indication of the key physiological differences between the zones along with their “engine” equivalents. They are included because Zones 4-7 take their names from the distinguishing features of these. The actual names are not really that important when starting out*. The key takeaway is that efforts taking 3-8 minutes feel quite different from those taking a minute or less and all of these are quite different from those taking around an hour which in turn is quite different from an effort taking several hours.
The table illustrates the first benefit of zones. They can help provide focus. Indeed if you do nothing more than ask yourself before every training session:
- “Do I want to improve my engine and/or something else this ride?”
- “If engine which one?”
- “Do I want to improve its range or its power?”
- “If something else what exactly?”
i.e. “What zone do I want to improve?” You will already have the fundamentals of a good training approach in place.
Returning to the road racer from the previous section, it may be that they can stay with a group on the flat and longer ascents. But when the hills get steeper and only take a minute or so to climb they struggle. So it looks as if they need to improve their zone 6 “turbo”, provided they can do this without having an impact on their other zones. So a coach may devise a training plan that will build zone 6 while maintaining their other zones at a steady level. That is not the only option however as we shall see later.
The table is not specific to cycling. It applies to most every from of physical activity and/or sport. Running to catch a bus is a zone 6 activity, lifting a heavy suitcase zone 7, walking the dog zone 1 (or 2/3 depending on the breed and anywhere from 4-7 if she gets a scent and hurtles of in pursuit!).
As cyclists we just happen to be particularly lucky that, with the help of a power meter, we can take zones one step further than most other sports and put precise numbers as will be shown shortly.
One final thing to note about zones is that they are not silos. The various physiological systems underlying them may well impact several zones. This impact may be positive or negative. For example even crit riders who never race for longer than an hour or so will most likely benefit from spending some time training in zone 2 as this can help muscles deal with the by products of high intensity exercise. Conversely a rider whose specialty is long time trials where zone 4 is important would not be advised to spend much time in zones 6 and 7 as the changes this produces will only have a negative effect on their performance.
* If you are interested in a deeper understanding of the physiology that underlies zones (and much more) I would recommend Andy Galpin on Youtube. He covers everything you need to know ranging from 5 minute introductions to hour long deep dives.
Why Power is Important – the Basis of Fitness
The starting assumption of this article is that a rider wants to get fitter. But what, exactly, does being “fitter” mean if you are a cyclist.
It is quite simple.
Being fit is the capacity, over time, to generate energy and transfer it to the bike. The more energy you can produce and the longer you can do it then the fitter you are.
True, there is more to being fit such as the ability to recover from and repeat hard efforts together with being able to generate energy efficiently, so conserving limited fuel.
And being the fittest will not necessarily make you the fastest. Turning fitness into actual speed means dealing with the factors that make you slower (aerodynamic drag, force of gravity, rolling resistance and drivetrain efficiency).
And the fastest rider will not always win. Converting speed into a place on the podium requires mastery of other factors such as pacing, nutrition, bike handling and tactics.
Still the need to produce energy and keep producing it at as high a level as possible is fundamental if riding a bike in pursuit of a performance related goal. All other things being equal then the rider that can do this best will win. (A top professional cyclist, for example, can produce more than twice as much energy per hour compared to an average cyclist of the same weight and consequently will always ride much faster for further.)
“Energy over time” is more succinctly called “power” by physicists who measure it in “watts” (or “W”), with “wattage” being a term to denote the power of a device or engine.
Cycling borrows these terms and puts them into practical effect by means of the power meter. So when a cyclist rides at 100W they are generating enough energy to keep a lightbulb with a wattage of 100 bright. (For a more extreme example search for “cyclist vs toaster”)
Power meters come in a variety of types but most measure two key values:
- The force applied to the pedals. More specifically the aspect of the force that causes rotation or ”torque”.
- The speed at which torque is applied. (Most power meters are attached to the crank so they simply measure cadence which, combined with crank length allows this value to be calculated)
Multiplying these two results in power. Cyclists have always known that if you want to go faster you push down on the pedals harder, spin them quicker or, ideally, do both at the same time. All that power meters do is measure this and produce a standard number of the result.
Power is produced by our muscles and so those with more muscles tend to produce more power. However extra size and weight means aerodynamic drag and gradients will slow these riders down more. Broadly speaking these two effects cancel each other out. So, when comparing riders, wattages are sometimes expressed as a power : weight ratio (W/kg).
What makes power special as a measure, compared with say your speed or heart rate is that it is a universal currency. If you know someone can average 25mph on a ride with an average HR of 140bpm you really cannot make any judgement about how fit they are. On the other hand knowing a cyclist can average 400W for an hour, regardless of whether this is on a Wattbike at the gym, up a mountain climb or in a long time trial instantly lets a coach know that they are pretty good, especially if that equates to over 6W/kg.
This is not to devalue other measures such as speed, heart rate and RPE. They are important and can become even more so when combined with power measures. For example a TTer seeking to improve their aerodynamics or testing equipment options will be interested in anything that increases speed while keeping power constant and/or seeing if a more comfortable position that produces more power can be achieved without sacrificing speed. For all riders a fundamental measure of improving fitness is that you can do more with less effort. Seeing power go up while HR and RPE stay the same is one sure sign your training is working.
Adding Power to Zones
Fitness varies by zone. Some riders are great at short distances, some at long, some at all. Combining power and zones provides a means to understand in a precise way for each individual athlete.
There are a number of different ways to do this. The one I would recommend is the simplest in concept.
First: Pick a sample duration for each of zones 4-7. A recommendation would be 5s for Zone 7, 1 minute for Zone 6, 5 minutes for Zone 5 and one hour for Zone 4. The reason for suggesting these is that they make comparisons with other riders easier as we shall see shortly. But feel free to choose others or have more than one duration per zone if you like.
Second: set aside a couple of weeks and plan sessions aiming to go as hard as you can for each duration. You will probably already know what brings out your best. If you have already been recording rides with power say on Strava or another tool like Zwift you can pick your bests from there. (Do not use “estimates” of power from any software tool though. You have to be using a real power meter.) Go hard, that is more important than holding the full duration. So for Zone 4 if you give it all you have but pop after 40 minutes that is fine.
Honestly, if you do not feel you have hit your best it really does not matter. One key benefit to training with a power meter is that it is an iterative process. If you results are too low they will soon go up as you start your workouts.
If time permits then it would also be nice to get an example of Zone 3 and Zone 2 but these are not essential. They can be added as and when you feel you have the data.
The result of will be a table that looks something like this, (which shows my bests for the current year)
|7||5s||748||Hard sprint on final straight towards home|
|6||60s||485||False flat into first climb out north|
|5||5 minutes||373||Race first 5 minutes to establish break|
|4||1 hour||301||Race full on from start to finish|
|3||2.5 hours||269||Alpe du Zwift repeats|
|2||5||212||Best 5 hours of 7 hour gran fondo|
That is it. Once done you will have your starting power zones. Now to put them to use.
Using Zones to Set Power PB Targets
The process outlined in the previous section will give you a baseline of how fit you are, by zone. Changes in the wattage for a zone are changes in your fitness. You can expect of the course of a training period that the watts for each zone may go or or may go down. The only thing that you would not expect is that they all stay the same.
A straightforward goal during each season and year on year is to regularly retest yourself and see how you are progressing. If your watts are increasing in some or all zones then you are getting fitter. You should be riding faster and/or further as a result.
As a beginner it is fun just to aim to set new PBs for every zone. This will encourage you to try lots of different types of events which will widen your horizons and is a good way to find out what you are best at and enjoy the most. Once you become more specialised then some zones will be more important than others so you will need to be more selective. Still one result of this specialisation should be more rapid improvement in the zones you prioritise though it may also mean results in a different zone go down.
Mix your tests up, not just touching every zone but also changing either power or duration. Say you have plateaued at your zone 5 test. Just hit the reset button and try going another 5 seconds longer at the same effort or for 3/4 minutes at higher watts. That counts as a PB. This is great training in itself and will prepare you for times when you need to dig deep for longer or harder.
Also use these tests as opportunities to see what works best for you in terms of preparation. Some riders ride best following an easy day. Others ride best after a hard day. You will only find out what sort you are by trial end error (Graeme Obree failed by over a kilometre in his first attempt at the hour record. He barely slept overnight, came back the next day, rode the extra kilometre and more and set his first world mark).
These power targets do not need to replace other targets e.g. race placing or Strava. To the contrary they should complement each other. Improving your power will result in better places/times and going for places/KOMs is one of the best ways to test your power.
One advantage of tracking power PBs is that these are less subject to bad luck. Say you have set a target of going sub hour for a 25 mile time trial and have the misfortune to puncture in the first few minutes. The target is now impossible but that does not mean all is lost. You can fix the puncture and channel your frustration into setting a new power PB for the remainder of the race, aiming to ride above your zone 4 best for the rest of the distance. If you manage this not only will have the satisfaction as a reward but also the experience will be great preparation for you next 25. You may find that you have set a new PB for 58 minutes and averaged over 25mph in the process, so next time should be a breeze barring misfortune. Even if you try and fail it will be time better spent that just limping back to the start feeling sorry for yourself as you have learned about your limits and what improvements may be needed in terms of power and/or aerodynamics for the future.
An additional spin on power targets is to set them in terms of W/kg. If your target events include any amount of climbing and/or you want to lose weight this is especially relevant and can be an additional motivator. This way you win if you either increase your watts or reduce your weight and win double if you manage both. (Tools like bikecalculator.com can be used to give you a reasonable estimate of how long it will take to do a climb and can be used as an additional incentive if you have a trip planned with a special target climb in mind).