Zone 5 – Above Threshold

This zone is a very intensive effort. We build lactate acid very quickly in it. Although lactate acid is something we want our bodies to becoming better to work with and to use as fuel, there becomes a point where you start to produce a lot very quickly and the body just cant deal with it as well. It can leave the muscles feeling tired/heavy or tight.

Used correctly this zone is brilliant to help you progress. Work for too long and the legs and body will want to give up, but short burst in training with plenty of recovery will enhance your posture/max speed/lactate tolerance and more importantly be fun!

What it is –

RPE – 9-10

% THR bike – Above 106%

% FTP bike – Above 105%

% THR run – Above 100% or 3-5km effort or feel

How do we factor it into training

These efforts are again very high in effort. In order to get the best benefit from them you would have roughly double the length of time to recover than the interval itself lasts in length. It gives you time to properly prepare for the next one. The working interval would in general last from 10 secs to up to 3 mins depending on the phase of training your are in personally working towards your event

Eg for a session

30 secs Z5 – 60 secs Z1 recovery


90 secs Z5 – 3 mins Z1 recovery

Would you race in this zone?

In short yes, but for lower distances/duration. you would be looking towards a 3-5 km run race. 5km at this level would be tough and depends on weather you take 15 mins or 25 as if you are a 15 min 5km you lasting a longer time. In terms of a bike, around a 15 min TT duration. If it last much longer you can probably survive at the HR level but the performance may be actually starting to lower. Also a good race/event at this level could take a few days to recover properly so allow for this

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