Using Power to Improve Your Time Trialing

By Marilyn Trout | 07/27/11

Photo © Jonathan Devich/

We’ve teamed up with Marilyn Trout, certified USA Cycling Elite Coach to answer Voler Newsletter List members’ training questions. You can view her coach profile at Send your cycling inquiries to Marilyn, and for a limited time, if yours is selected to be answered in our Training column, Voler will send you a $20 gift certificate that can be used towards any purchase from the Voler Store at To submit your inquiry, e-mail her at, and type “Voler Training Question” in the subject line of the e-mail.

The following tip is a reprint of a June 2009 question submitted by from Voler E-Mail List member Jim MacDonald – still an excellent subject!

Using Power to Improve Your Time Trialing


I did a 40K Time Trial basically holding my wattage at my critical power point. I am also going to do shorter Time Trials of 5K and 10K. What power level should I strive for in these shorter distances?

Jim Macdonald


A very good question and you actually have given somewhat of an answer by assuming that your power will be different in the shorter distances. We need a few more details to give some sound training and racing advice.

Further Details

  • Jim's reference to Critical Power is just another way of describing average power, the power that can be maintained for a certain amount of time. So for Jim's 40K Time Trial we would be looking at CP60 which was 254w for the race.
  • His training power leading up to the 40k was based on a number of tests to figure out what his Power Threshold (PT) in order for a training plan to be established:
    Test #1: 1/7/09 CP20 - 230w
    Test #2: 2/26/09 CP20 - 236w

Most riders are familiar with the typical heart rate based training system with its training "zones" using a heart rate monitor. The power based training zone approach is based upon a similar concept which produces general physiological adaptations as well as specific fitness gains at a particular critical power.

After a couple months of training, with one of the objectives being to raise his PT, Jim realized a significant CP20 increase during his 40k TT on 3/15/09 to 260w. Thus, his Power Threshold training zone went from 214-249w to 237-275w. Other useful data averages for the time trial; HR - 153 bpm, 96 rpm, 22.4 mph. (His sub-threshold heart rate zone is 146-155 bpm, so he zeroed in on a good target.) Since then his PT has increased once again to 267w, with the threshold zone, 243-282w.

OK… on to the shorter distance time trials of 5k and 10k that is of concern here and also very much a part of achieving his '09 goals. Let's take a look at the power numbers:

CP6 - 304w, CP10 - 284w, CP12 - - 281w, CP15 - 273w.

These power scores, also seen in the graph below, can be used for specific interval work to train for the 5k, the medal winners in his age category have times of under 9:40 and 10k, times are around 15:00.

file: 0906_criticalpower.jpg


According to the training and racing you have done, it would be reasonable to aim for a wattage around 281-284w in these shorter time trials. If you are having a good day for the 5k, you could aim for a slighter number without "burning your matchbook." It is also important to keep in mind, the kind of gears you've been using in training, heart rate you've had in the past for this effort (~ 150bpm) and optimal rpm (~ mid 90's) that have helped you perform at your best.


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