Training Protocols and Intensity Distributions

Rather than just randomly exercising or beasting it every time we go out we can use the zones to develop a targeted training programme. Training-intensity distribution (TID) defines how much training we do in each zone during a training programme.


The main protocols are Polarized, Pyramidal, Threshold/Sweet Spot, HIIT and Base/HVLI. Using the three level model for simplicity we mix the quantity of LIT (LT1), MIT (LT2) and HIT efforts.

Sweet Spot and Threshold

Sweet Spot training incorporates high volumes of training at around 75-85% of max heart rate with a focus on the upper end. That is in the top of LT1 to just below LT2. The kind of efforts you can maintain for 1 to 3 hours. Say climbing an alpine pass or a 50 mile Time Trial. Because the training is below LT2 you should be able to do multiple sweetspot sessions in a week. In theory it hits the sweet spot between intensity and volume without overly tiring the body. Proponents claim sweetspot maximizes limited time when training for endurance events. A sweet spot session may consist of longer intervals with some rest in between, say 3x20 minutes in the zone.

Threshold is at 85 to 95% of Max HR, that is above LT2. Seiler calls this level HIT (High Intensity Training) on the three zone model. At this level lactate will build up in the bloodstream and you’ll only be able to maintain these kinds of efforts for shorter periods.

This doesn’t tell us how much Sweet Spot or Threshold we should be doing in relation to other zones but on the three zone scale it is generally accepted that a TID in zone 2 would be the majority.

Over and under

Over/Under intervals involve working just either side of your lactate threshold (LT2) or FTP. The goal of these intervals is to load your body with an abundance of lactate during the ‘Overs’ and then force it to deal with and process the lactate during the ‘Unders’, when you will still be working at a relatively high intensity. Again this could be part of a Threshold TID


High-intensity interval training (HIIT) consists of short, maximal-intensity anaerobic intervals with short recovery periods to the point of exhaustion. A workout will typically be less than 30 minutes in total. There are a number of different protocols for HIIT under various names: Tabata, Crossfit etc.

An interval would be 20 seconds with 10 seconds of recovery. A 2015 study showed that HIIT training led to improved cardiovascular fitness and significantly better VO2 max improvements compared to endurance training.


High Volume executed with Low (LOW) Intensity (LT1) and prolonged duration is thought to be a fundamental training concept in preparing for endurance events. This type of exercise improves VO2peak by increasing stroke and plasma volume and induces molecular adaptations that improve the efficiency of metabolic key components for energy fueling.

This training model has been validated to improve health and fitness for untrained and weight-loss individuals but may not be the best choice for optimizing training of previously fit/athletic populations with competitive sport goals.


The majority of time is spent in Zone 1, a moderate amount of time in Zone 2 with the smallest amount of time in Zone 3. The Zone 3 work could correspond to a weekly long interval season. A lot of endurance athletes do pyramidal training by default during the race season as race efforts are mainly in zone 2.

The 3-week Tour de France as an indicator of exercise intensity during a competition. Analysis has shown that the relative contribution in each intensity zone (3-zone model) was 70%, 23% and 7%, respectively. (Lucia et al (87))


There has been a lot of talk about elite sportsmen and women spending most of their training time pottering around doing very easy sessions with a bit of HIT work. Dr. Stephen Seiler has studied a number of top athletes and claims that their training is organized on an 80/20 model, with 80% of the work below LT1 and the rest well above that level. This kind of training is called polarized because very little time is spent in the LT2 zone.

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