Despite the various interval designs, these efforts all broadly do the same thing. More specifically, they seek to hold you an an intensity where your oxygen consumption is close to your VO2max. Physiologically there’s fairly little to differentiate between them in this regard.
That being the case, when focussing on a specific physiological goal, we think it’s better to pick just one or two styles of interval that you enjoy and find easy to execute (check out our FREE WORKOUT LIBRARY for some recommended sessions).
This has several key benefits when it comes to training optimisation.
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Firstly, it helps avoid ‘failed’ sessions that arise as a result of you not being familiar with a particular interval session. This might arise as a result of bad pacing (e.g. starting too hard), or route selection (e.g. running out of road before the end of an interval). By repeating the same interval session, you will be able to iterate and finesse your pacing strategy for these intervals, and perform them at a higher quality each time. You’ll also be able to identify routes or sections of road that work particularly well for your chosen interval type.
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Secondly, by performing the same interval session over again, it’s much easier to spot signs of improvement in your training. For example, it’s much easier to notice whether your perceived effort level or heart rate are now lower for a given power output, or whether you’re now able to complete your intervals at a higher power, cover more distance or complete an additional interval rep.
This latter point is key to understanding whether your training is actually having a meaningful effect on your fitness, and leads nicely onto our next tip:
2. Align your ‘key performance indicators’ with your training goals
Assessing progress is an important aspect of training, helping to keep you on the right track and to ensure that your time and energy are well-spent. However, time and again, we see athletes using FTP as their one and only marker of progress. This is often used irrespective of the time of year, training goals, and cycling discipline.
However, FTP (the maximum power you can sustain for roughly 40-60 minutes) only provides a very one-dimensional snapshot of your fitness profile, and may not be relevant for your training goals.
As a key example, during a typical ‘base’ training phase (which usually runs through the winter and early spring months), a common goal is to build general aerobic fitness. This includes aerobic efficiency, ability to use fats for fuel, and general endurance (i.e. ability to ride for longer periods of time).
During this base phase, developing FTP is not a priority, and we may, or may not see improvements in FTP. Whether we happen to see improvements in FTP will depend on your fitness level leading into that phase, and your specific physiological profile. Changes in FTP tell us very little about whether the base training phase has been effective.
Much better markers to look at through this training phase include:
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Improvements in your ratio between heart rate and power output.
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Improvements in your ‘ventilatory threshold’, which can be assessed via the talk test (see here)
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A subjective sense that your longer rides are becoming less fatiguing and/or that you need to eat less on these.
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Improvements in your ability to produce a hard effort at the end of a long ride. Oftentimes in real-world races, it’s not the person with the highest FTP when fresh who wins (we like to call this the ‘fresh-hold’ power). Instead, it’s the person who can produce the highest FTP after several hours of hard riding!
These markers or so-called ‘key performance indicators’ all directly relate to the aspects of physiology that we’re looking to develop through the base training phase, and are much more reliable indicators that your training is having the desired effect than FTP.
Making sure your key performance indicators align with your training goals gives you the best chance of understanding which types of training are working well for you, and which aren’t. It also helps prevent you from mistakenly ditching types of training that are actually helping you and from getting demotivated by seeing an apparent lack of progress when you are actually improving.
We’ve included a summary below of common physiological attributes and suggested key performance indicators:
Endurance/Fatigue-Resistance
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A subjective sense that your longer rides are becoming less fatiguing and/or that you need to eat less on these.
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Improvements in your ability to produce a hard effort at the end of a long ride.
Aerobic Efficiency
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Improvements in your ratio between heart rate and power output.
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Improvements in your ‘ventilatory threshold’, which can be assessed via the talk test (see here)
Threshold Power/FTP
VO2max
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Improved ‘maximal aerobic power’ in ramp test
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Improved maximal power output over 3-8 minutes (or faster time on segments in this time range)
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Improved power output during ‘VO2max’ interval sessions*
Anaerobic Power
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Improved power output during anaerobic power* interval sessions
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Improvements in maximal power over roughly 30-seconds to 120-seconds (or faster time on segments in this time range)
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General subjective sensation that you’re feeling more ‘punchy’ and able to respond well to changes of pace in a group ride/race.
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Increased W’ in critical power test
Anaerobic Capacity
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Ability to complete higher number of anaerobic stamina intervals*, before reaching fatigue.
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Increased W’ in critical power test
* Check out our FREE WORKOUT GUIDE for examples of these workout types.
3. Changing Plans is Good
It might sound strange, but a key sign of a well-executed training plan is that you didn’t stick to the plan!
Any training plan is only ever a best guess at what the appropriate training for a given day will be.
However, a whole host of factors such as work and family commitments, lack of sleep, and under-fuelling can add unplanned fatigue, which might mean that the session you had planned to do today is no longer suitable.
A key example of this is with high-intensity interval sessions (i.e. efforts that require you to ride above your threshold power). These efforts are often HARD, and you need to be at least reasonably fresh in order to hit the target intensity range, and trigger the intended physiological adaptations.
If you’re not sufficiently fresh to reach the target intensity range, then this isn’t the right day to do the session.
Cyclists are typically very motivated and hard-working individuals, and we often see people trying to persist with an interval session when they are too fatigued, just because the session was in the calendar and they don’t want a ‘failed’ session.
However, this is a bad decision, not only because the efforts won’t be performed at the right intensity (and thus won’t trigger the desired physiological response), but also because you’re not allowing the body to recover when needed. This can result in subsequent training sessions also being curtailed or reduced in intensity (and in extreme cases can even lead to overtraining!).
Ultimately, if you don’t allow flexibility in your training plan, this can actually be more disruptive to your training than simply taking an extra day of recovery and then quickly getting back on track.
If you do need to skip a training session to take some extra recovery, we’d also suggest that you don’t try to play ‘catch up’ later in the week (i.e. by trying to squeeze the missed session in at a later point). This can also be disruptive to subsequent training. For example you might then find you’re too fatigued for the long endurance ride you had planned, and may end up cutting this short.
The bottom line is that if your body needs some extra recovery, then you should be open to including this in your plan, and shouldn’t worry about any sessions that are missed in the process!
4. Don’t stick religiously to ‘standard’ training intensity zones
There are various ‘standard’ training intensity zones or ranges for different types of sessions.
A basic example is the seven zone system, which we describe in this article, where zone 1 (<60% FTP or <60% Max HR) is an intensity that supports recovery, zone 2 (60-75% FTP or 60-70% Max HR) is an intensity that develops endurance and all-round aerobic fitness, and so on.
You’ll also find structured training sessions, such as those found on platforms like Zwift or TrainerRoad, often include intensity targets based on your FTP.
However, these intensity zones and targets are based on population averages. In other words, they are prescribed based on the power or heart rate that an average cyclist needs to hold in order to elicit different metabolic or physiological responses.
In reality, depending on factors such as your genetics and the types of training you’ve done in the past, these intensities may not suit you as an individual.
That being the case, we always suggest paying close attention to how different intensities feel subjectively and iterating your effort level accordingly.
In our free workout guide, we always include a description of what a session should feel like subjectively, as well as prescribing a power and heart rate range (rather than fixed target), which should suit a broader range of people.
Paying attention to your subjective feelings is particularly important in interval sessions above your threshold power, where there is much greater variability in power output between different people. As a general rule, we encourage our athletes not to use Erg mode when performing interval sessions indoors, as this can unnecessarily constrain your power output and lead to a lower-quality session.
Importantly, the ability to hold more/less power than the ‘typical’ intensity prescription doesn’t make you a better/worse cyclist.
As a specific example, a cyclist training for ultra-distance events will ideally have a fitness profile that means they find it hard to produce power above their threshold. This is because their threshold power sits very close to their VO2max, and have honed their fitness so that they are aerobically very efficient. In this example, it’s actually a very GOOD sign that this cyclist can’t hit the same power (relative to FTP) as the ‘average Joe’ in a set of VO2max intervals!
In any event, whatever your physiological profile, our key advice is to listen closely to your body when performing your training sessions, and have a good idea of what each session type should feel like subjectively.
5. Start your intervals conservatively
Most people tend to pace their intervals so that the first one is their ‘best’ in terms of power output, and then power starts to gradually drop interval-by-interval as they become fatigued. Calling on terminology used in running, we refer to this as ‘positive splitting’ your efforts. This is quite an easy pattern to fall into as you’ll usually be feeling your freshest in the first effort.
It’s pretty obvious that going super hard in the first effort is bad. This can lead to the interval session being aborted early, or an inability to hit the necessary intensity in latter intervals in order to stimulate the intended training adaptations.
However, what many people don’t know is that, even if your pacing is a better so that you’re still able to hold all intervals in the intended intensity range, there can be a benefit to intentionally starting more conservatively, and then picking the power up later so that your last interval is your strongest. We refer to this as ‘negative splitting’ your efforts.
We compare the two scenarios below.