VO2max
Bike Sessions
The Aim of VO2max Sessions
VO2max is the aerobic ceiling; these sessions aim to drive the physiological mechanisms that will help to raise this ceiling.
There are four main types of these sessions
Micro intervals - aimed at increasing the duration you maintain a cardiovascular stress over 90% of VO2max.
Square-wave sessions or block sessions where you hold a set power for an extended duration. The duration of these intervals will vary from athlete to athlete. The intensity is the key component.
Preload Sessions - These start each interval with a significant spike in power designed to switch O2 kinetics and lactate production on quickly, then immediately followed by a block of work at the lower end of the normal VO2max range.
Mixed sessions - these sessions use type 1 & 2 intervals together to stimulate VO2max.
Both types of sessions have their pros and cons and are used for slightly different purposes.
Micro Intervals
Intensity: ‘On’ 110-118% VO2max / ‘off’ 75 - 85% FTP
Interval Duration: 30 - 40s / 20 - 30s Recovery
Number of reps per block: 6 - 12
Number of sets: 2 - 3
Time at VO2max: 12 - 24min (this is the crucial part, in full training we are aiming to get as much time as possible)
How to execute them
There is a range within the ideal intensity; use this to maximise the session. We are aiming to get as much time as we can close to VO2max, so doing the reps outside of this will reduce this time.
Too hard and you won’t be able to do enough reps, too easy and you are taking too long to reach the threshold (if at all).
Pro tip: It's better to start the higher end of your range for a couple of reps, then if that’s not sustainable, knock it back a little (but still within range). This increases HR, O2, etc, quickly and results in more time over 90% VO2max.
The most precise method of executing these sessions is on the trainer; you have the greatest control over the intensity, ensuring you are working at the right intensity at the right time.
ERG mode is an excellent option for these sessions; see more on the the trainer options in the additional box.
Layout of the various types of VO2max sessions
Square-Wave / Block Intervals
Intensity: ‘On’ 110-118% VO2max
Interval Duration: 1m30 - 4min / Recovery 1:1 or 1:2 at 45 - 60% FTP
Number of reps: 3 - 15
Time at VO2max: 12 - 24min (this is the crucial part, in full training we are aiming to get as much time as possible)
We aim to find the best duration for you for each of these intervals. Too long with a lower FRC (Functional Reserve Capacity), and you will not be able to complete enough reps to make the session work. Too short, you will not hit the target of 90% VO2max for long enough in the session.
How to execute them
These can be performed on the trainer or outside, but if outside, ensure you have enough clear road to hit your targets.
If doing them IRL or in free mode on the trainer, accelerate up to target power smoothly over the first few seconds, and avoid sudden and uncontrolled sprints to get up to speed.
Once up to target, focus on holding a smooth power delivery.
Often, these sessions are performed on base bar or hoods, wherever you get the best power, we want the highest physiological stress. There are some occasions where we will specify performing them aero. However, triathletes rarely hit this hard in the TT position.
As these are very hard intervals that are on the limit of what you can do, there is a reasonable chance of being unable to complete the number of reps we specify at the right intensity. If you have given your best shot, it’s fine. Do as many as you can at the correct intensity. Do not soften them so you can complete the required number.
Pro tip: don’t beat yourself up if you cannot complete these sessions. Roll with it, life is not a precise science. If you have done as much as you can, you can be satisfied with the day’s work.
Preload and Mixed Intervals
These sessions use a combination of types 1 & 2 and introduce a spiked session which start each rep with a significant surge.
How to execute them
These can be performed on the trainer or outside, but if outside, ensure you have enough clear road to hit your targets.
If doing them IRL or in free mode on the trainer, accelerate up to target power smoothly over the first few seconds, and avoid sudden and uncontrolled sprints to get up to speed.
Once up to target, focus on holding a smooth power delivery.
Often, these sessions are performed on base bar or hoods, wherever you get the best power, we want the highest physiological stress. There are some occasions where we will specify performing them aero. However, triathletes rarely hit this hard in the TT position.
As these are very hard intervals that are on the limit of what you can do, there is a reasonable chance of being unable to complete the number of reps we specify at the right intensity. If you have given your best shot, it’s fine. Do as many as you can at the correct intensity. Do not soften them so you can complete the required number.
Pro tip: Learn to improvise the sessions, don’t just be happy that you have completed the set session. If you finish these sessions too easily, we need to either re-test FTP and increase intensity or we need to be doing more reps. The goal is to accumulate time over 90% VO2max, so if you aren’t doing this in the sessions, you are not getting as much from your hard work as you should.
Using Zwift or other platforms for the session
If you use Zwift (other apps are available), you have a few options for performing these sessions:
Structured Workout in ERG
Structured Workout without ERG
Free mode
Using ERG mode means the trainer will control the resistance so that as long as your cadence is constant, there will be minimal variations.
Without ERG on the app will tell you what you need to do, but will not control the resistance. You use your gears and/or cadence to increase or lower power. You can choose any route to do this, the elevation changes are not felt in the session.
Free Mode and choosing a long climb such as one of the Portal climbs is our preferred option.
Fuelling
These sessions are at very high intensity and you will burn carbs at a very high rate, and continue to do so for a while after you ease off.
Typically, we see rates of 4 - 7-g/min at pVO2max, depending upon the atheltes physiological profile. That equates to ~ 120 - 210g of carbs in 30-min.`
If you start the session fully replete, you can perform even the largest session without carbs during the session.
However, this is not optimal for execution or recovery
Consume 30 - 60g of carbs during a standard session, to maximise your perfomance in the session and recover faster after the session
If performing these intervals as part of a longer EE ride, consume 60 - 100g per hour around the VO2max portion with standard rates on the EE portion.