Monday, December 10, 2012

Normalised Power for TTT efforts

Having made a few tweaks to the code in the previous post, I now have a method for finding appropriate TTT replication sessions to do on ones own.

All I have really done since yesterday is allowed for changing of the drafting factor (i.e. how much energy is saved when not on the front), the total time for each on/off section, and the number of repeats that make up each interval.

In addition, I have realised that all the results will be directly scalable if you wish to use the workout at an intensity other than 100% FTP as the session's Normalised Power - simply multiply it by how hard you want to go.

From this, I have then entered a few representative values to get some basic sessions:

- Base case: each man is the same strength, the draft factor is 0.7, the total on/off time is 3', the total interval time is 15', and the workout is done at 100% FTP

P_on = 120.8 (1')
P_off = 84.5 (2')

- The strong man: the rider is sufficiently strong to be doing 50% of the work. The total on/off time is now 4', with the interval time 20'.

P_on = 113.3 (2')
P_off = 79.3 (2')

- The weak link: the rider is weak and only able to contribute 10% of the work. The total on/off time is 5', with the interval time 20'

P_on = 135.5 (30'')
P_off = 94.85 (4'30'')

This last session, in particular, is very interesting. It demonstrates that if a rider is significantly weaker than his teammates, he is essentially required to ride an individual time trial type effort for the majority of the time, interspersed with short, very intense efforts. Knowing this in advance can only help the rider in question (if we assume he cannot raise his relative strength with respect to the others) - he can train to be able to perform such a non-standard workout and therefore contribute maximally to the TTT effort.

Altering the sessions above to be done at 95% or 105%, for example, would be an easy way to adapt them to a 5x5' or 2x25' session. However, I think that 15-20' intervals are about right for this kind of work.

The obvious question from all this is: how do we determine how long each man should be on the front for?

I will be answering this question shortly, based only on knowing each rider's FTP.

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