Bike Sessions
Shuttling Sessions
The Aim of Shuttling Sessions
The Lactate Shuttle theory describes the body’s function to carry lactate from the working muscles, where lactate levels rise, through the blood to better-oxygenated domains where lactate can be used as fuel.
Well-trained athletes have such low blood lactate levels because they efficiently clear it in the producing muscle it. This is a great advantage, but a complex mechanism too. Because during bike riding, lactate is mainly produced in the fast-twitch muscle fibres, whereas it’s mainly cleared in the aerobic slow-twitch muscle fibres. This process involves different lactate transporters and enzymes.
These sessions aim to stimulate an increase in the number of transported, enzymes and mitochondria to improve lactate clearance and thus performance.
We use two main types of session (detailed in separate boxes)
Moderate
Significant
However, both employ a higher intensity bout of work above FTP and a lower intensity effort that is at or above Lactate Threshold 1 (LT1)
Representation of Lactate Thresholds 1 and 2, with Tempo and SST highlighted
mShut - Moderate Shuttling
These comprise of 2 to 4 main intervals, that involve a harder and easier (but not rest) element. See the Training Peaks graphics for examples
The ‘on’ part is at 103 - 108% FTP/LT2
The ‘off’ part is at 80 - 85% FTP in the Tempo zone.
The key to these sessions is ensuring you are above FTP for the on part and recovering a little above LT1. After a few reps, this will not feel like a recovery, though.
Most sessions begin with an initial rep of work above FTP to flood the body with lactate, before beginning the session proper.
You should think of these sessions as 2 - 4 reps with some variation in intensity within each.
How to execute them
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 this session; see more on the the trainer options in the additional box.
sShut - Significant Shuttling
These comprise of 2 to 4 main intervals, that involve a very high intensity effort and an easier (but not full rest) element. See the Training Peaks graphics for examples
The ‘on’ part is at 120 - 125% FTP/LT2 (Low FRC Zone)
The ‘off’ part is at 70% FTP (Extensive Endurance zone).
The key to these sessions is ensuring the on part is hard enough to produce enough lactate to clear in the off phase.
The off is much easier than the mShut sessions but still not easy.
Most sessions begin with an initial rep of work above FTP to flood the body with lactate, before beginning the session proper.
You should think of these sessions as 2 - 4 reps with some variation in intensity within each.
How to execute them
The structured workout option is excellent for this workout, with Zwift or other software telling you the power you need to hold but not controlling it (i.e. with ERG mode).
The harder efforts are really hard, and there may be some variation in them, you need a little flexibility to either go a little harder or a little easier to maximise the session. As the on part is so short its best not to be fiddling with buttons to increase the resistance.
Fuelling
These sessions are high-intensity, so you should be fuelling these to help with session execution and recovery unless specifically part of a longer session they are not usually long.
Aim for ~ 50 - 80g per hour.
Ensure you get a carb/protein recovery meal in after the session to help with adaptation and recovery.
Fuelling
These sessions are high-intensity, so you should be fuelling these to help with session execution and recovery unless specifically part of a longer session they are not usually long.
Aim for ~ 50 - 70g per hour.
Ensure you get a carb/protein recovery meal in after the session to help with adaptation and recovery.
Using Zwift 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.