Beginner's Guide: Training Zones
Everyone who rides a bike with the intent to go faster than someone else can benefit from structured training. Whether you opt for a popular online training app, buy a training plan online, coach yourself or hire a professional coach, one of the first things you'll need to do to train with structure is establish your "training zones".
What are training zones?
Training zones are ranges of power, heart rate, speed, or rate of perceived exertion (RPE) where an athlete works for specified times to achieve desired aerobic, metabolic, or neuromuscular adaptations. There are many different training zone systems in use in endurance sports today. No one is necessarily better than another, but some are more complex and others simpler.
It is important to note that human physiology doesn't function like a "light switch"; training in one zone will not achieve a specific adaptation which then immediately stops when you go into the next zone up or down. Additionally, your zones can vary slightly day by day based on fatigue, illness, sleep, nutrition, temperature, etc. This is where being dialed into how riding at various effort levels "feels" is important to gain with experience. That said, having heart rate or power zones in which to target your training is extremely beneficial and will make your riding much more productive than simply winging it, especially as you gain that "feel."
As a coach, I generally use a seven-zone scheme (ref: Coggan, 53-4) as below.
Zone 1: Active Recovery - very light efforts, used between intervals or as standalone rides to aid a rider in recovering from races or a series of hard workouts.
Zone 2: Aerobic Endurance - moderate efforts or "all day" pace, RPE of 3 on a scale of 10. Most athletes will benefit tremendously from spending long rides, several hours in duration, in this zone. Most athletes will also spend most of their training time riding in "Zone 2." At the low end, this is "conversation pace", but at the high end, you'll know you're working, especially after a couple of hours.
Zone 3: Tempo - harder aerobic efforts, riding in tempo is sustainable for very long intervals or even a couple of hours in fit riders. This zone is sometimes referred to as the "gray zone" because it is too hard to be considered "easy", but not hard enough to force adaptations unless the duration is long enough. In short, riding for long periods in this zone can be very fatiguing. It is beneficial to ride tempo when building your aerobic base, but athletes should be cautious of riding in this zone during the race season when most rides should be relatively easy, or involve very hard efforts.
Zone 4: Threshold (and "Sweet Spot") - still primarily aerobic efforts, up to and slightly over your lactate threshold, RPE between 5 and 6. These efforts are usually sustainable for up to an hour, but intervals in this area are usually on the order of 10-20 minutes. Once you cross your "threshold", your ability to sustain power will drop off dramatically, your heart rate will rise, and your perceived exertion will be much higher.
Sweet Spot is essentially its own zone that incorporates the high end of tempo riding crossing into the low end of threshold riding. More on that at another time.
Zone 5: "VO2 max" or "Maximum Aerobic" - efforts slightly above your lactate threshold where your body is eventually maximizing oxygen uptake and your aerobic energy systems are tapped to their fullest capability. Efforts here generally last between 3 and 8 minutes and are repeatable several times on somewhat shorter recovery.
Zone 6*: Anaerobic Capacity - efforts significantly above threshold, RPE 8+; your muscles are drawing on stored glycogen (sugar) as a primary fuel source. Efforts in this zone are typically 30s out to 90s or a bit more, and are extremely fatiguing. While efforts here are repeatable, they are limited, they require much more recovery than lower zones between efforts, and they are very taxing on your body. This is where you're "burning matches".
Zone 7*: Neuromuscular/maximum power - these are maximal sprint efforts, where you are tapping into your body's ATP-Creatine Phosphate energy system, and also drawing on large amounts of muscle glycogen. Efforts here are not sustainable - these are your maximum effort sprints - and can only be repeated a few times, each requiring a great deal of recovery between efforts.
*In some zone schemes, Zones 6 and 7 are combined into one zone encompassing everything above your VO2max or maximum aerobic capacity.
A word about heart rate zone structures
My preferred heart rate zone structure deviates from the power zone structure above, specifically above threshold. Zones 1 through 4 are typical and even referred to by the same titles in many schemes: Recovery, Endurance, Tempo, and Threshold (or Sub-Threshold). Heart rate behavior below your functional threshold is predictable for most athletes. That is, your heart rate at a certain effort will tend to stabilize over time, and if it increases, it does so very slowly. The heart rate at which you achieve your functional threshold is referred to as your "Lactate Threshold Heart Rate" (LTHR). I'll talk about how to find that in the next article on setting your training zones.
These are general statements - rider physiology above functional threshold is highly individual. This is where understanding your specific needs, or having a coach who can dissect your strengths and weaknesses above threshold, can really pay dividends.
Once you get up above your functional threshold, your heart rate tends to climb until you reach your maximum heart rate after enough time. The harder you are working above threshold, the faster you reach maximum heart rate. Because of this "Zone 5" for heart rate zones is often combined with 6 and 7, and referred to as 5a, 5b, and 5c, or one single large "superthreshold" zone.
As mentioned, there are many systems of training zones out there. All of them intend to do the same thing: allow you to have some structure in your training. How you structure your training depends greatly on your goals and goal events, and your own personal strengths and weaknesses as a rider. In general, most cyclists interested in racing - whether sanctioned racing or weekend group throwdowns with your friends - will want to spend most of their time riding in "Zone 2", and then adequate time in the higher zones to achieve the results they want. That intensity distribution of harder riding is highly individual - that is where having a cohesive training plan or working with a coach can pay the greatest dividends for riders of all abilities.
In the next article, I'll delve into how to set your training zones by heart rate, and in the future, we'll tackle power. For now, get out there and put in plenty of time riding in Zone 2. Check out the previous articles (here and here) for how to execute those rides; they are the foundation of every rider's fitness, and most people can see significant gains by simply adding more quality time in the saddle.
Reference: Allen, Hunter, & Coggan, Dr. Andrew. Training and Racing with a Power Meter, VeloPress, 2006, pgs 53-4.