1.BaseAim of Session

Enable the development of base endurance and efficiency at low-intensities

Session description

WARM UP and COOL DOWN: No warm-up / cool down is required, session duration is total session time

MAIN SET: Zone 2 ride, keeping intensity near LT heart rate. Focus on keeping cadence up to help develop efficiency


Whilst aerobic fitness is described by the three parameters of VO2max, the lactate threshold and efficiency, the development of endurance comes from working sub-maximally for extended periods of time. The top end of zone 2 is marked by the lactate threshold: above this intensity the production of lactic acid  in the muscle (from carbohydrate stores)starts to outstrip its clearance in the blood. Below LT (i.e. in zone 2) the greatest proportion of energy comes from utilising the body’s fat stores. Building the time spent in zone 2 will make the body more efficient at burning fat for power production. The more efficient one gets the less need for carbohydrate use and therefore lower lactic acid production. This will cause a shift of the lactate threshold to a higher intensity i.e. improved endurance. For more information, see the factsheet on zone 2 training.

Application for the Rider

This session involves a steady-state ride at lactate threshold heart rate and / or power. Training at this intensity allows for this threshold to be pushed up from below, meaning that a rider might be more comfortable and experiencing less fatigue in longer rides. Therefore, increasing this threshold from 200 to 210W for example, would have a huge impact on the speed that can be comfortably maintained in a longer distance race.

The fuelling strategy for these rides depends on the aim of the session i.e. specifically endurance building, or looking to achieve energy deficit in periods of weight loss for performance gains. Whilst mainly burning fat, some carbohydrate is used, especially as one approaches the zone 2 upper border of the LT itself. The higher the quality of the session, the more likely a rider will need to feed i.e. use of energy drinks, bars and gels. Also, the longer the ride the increase in these ‘exogenous’ carbohydrates is warranted too.

Practicalities and tips!

  • Because of the nature of base rides, some riders find it easier to control intensity by using heart rate rather than power – simply because at this intensity, it can be hard controlling power – this is one instance where the lag in heart rate is a advantage in training monitoring! It keeps things more steady.
  • Rides to increase base endurance should involve as much time as possible just under the LT heart rate / power. The aim is therefore to keep your power in as narrow a range as possible i.e. time AT target intensity is more important than coming back with a ride average at target intensity. Keep the mantra of ‘every pedal stroke on target’; up or downhill, into a headwind or with a following wind.
  • In order to maintain quality as the session time increases, look to be taking on between 40 and 60g per hour of carbohydrate to support fat burning. “Fat burns in a carbohydrate flame”.
  • Working in zone 2 allows the concurrent development of efficiency, since the workload is not too high. Working at higher cadences is therefore included in this type of session – but remember, a higher cadence might increase heart rate / reduce power, so try not to be concerned if this is the case. It WILL improve with time!

Evaluation of the session

  • As above, time AT target intensity will score you most ‘points’. How much time did you spend within 10W of your LT power or 5bpm of your LT heart rate?
  • Remember, heart rate at LT tends to stay the same, even as you get fitter – what will happen though is you will be able to increase the power which brings back a heart rate at LT. You can track this improvement over the weeks of base development.
  • Over time, you will find it easier to extend the length of the rides without power dropping or heart rate increasing. See the factsheet on the heart rate / power relationship to learn about a useful index to track in your training. Once you have reached an ability to hold these two parameters steady in a ride, you are ready to increase the ride time, or increase the power target.
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