Power meters and power training have been around for a while in elite cycling and pro triathlon. Does power meter training for Ironman racers and in particular age groupers make any difference though, let’s have a look?

As with my previous posts, I am writing this from personal experience. I am not a qualified coach. I have however trained and raced bikes (and triathlon) for 25 years so have a lot of anecdotal experience.

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The story up to last August…

Before last August I had never seriously trained with anything other than feel and on occasion heart rate.

I was very much ingrained in the old school cycling world of ‘get the miles in and the rest will work out’. The aim was always a solid 2,000 + miles across the winter at 18/19mph averages then increasing intensity into the spring.

I used a similar method for my last Ironman – to read the race (and training) report for that one click HERE

That all changed when I decided to have a crack at qualifying for Kona this year.

The first thing I did was buy the update of Joe Friel’s Training Bible (highly recommended). Plus his power meter handbook.

To check out Joe’s website, click HERE

I then started working with a coach, who pretty much insisted on having one. So off I went to get a power meter – I also bought myself a Wattbike (Wattbikes count towards N+1 obviously).

So now you know the background lets have a look at whether power meter training for ironman athletes is worthwhile (in my opinion).

Me - not generating much power!

So, watt is different then (like watt I did there lol)?

Ok, first thing that is different, there is literally nowhere to hide with a power meter.

If you are having a bad day (or slacking) you know, very quickly! Heart rate training gives false metrics on the bike, because there is a lag between applied effort and work done.

Think of it this way, heart rate tells you the effort you are putting in. Power tells you the performance you are creating.

So would you rather measure effort OR performance.

Performance wins every time.

There are however some things that you need to take into consideration when working with a power meter.

1 – You Need To Know YOUR Numbers

There are a few variables with power meter training, it is not as simple as bolting one on and magically you are faster.

Power meter training is all focused around numbers and science.

The first thing you need to know is your FTP (functional threshold power), which is basically the maximum power that you can hold for an extended period of time.


Your Lactate Threshold (LT) which is slightly different and can only be measured in a lab through blood testing.

If you have no idea what these are then you definitely need to have a consultation with a GOOD coach prior to starting to work with power.

I will write up a post discussing the differences and the pro/cons of each soon, I will fire a video up of me doing an FTP test as well.

2 – You Need To Know How To Manipulate The Variables

Once you know your FTP or LT then you need to work out your training zones based on the following…

  • Zone 1 = <55% FTP (active recovery)
  • Zone 2 = 56-75% FTP (endurance training – long duration)
  • Zone 3 = 76-90% FTP (tempo training – improves sustainable power)
  • Zone 4 = 95-105% FTP (threshold – improves race pace)
  • Zone 5 = 106-120% FTP (VO2 max – improves short term high level efforts)
  • Zone 6 = 121-150% FTP (anaerobic capacity – short term maximal efforts)

You then need to structure your training based around the above numbers to improve the elements that you have pinpointed as weaknesses.

That is somewhat out of the scope of this blog, as said previously a good coach will help you here OR have a read of The Triathletes Training Bible by Friel.

3 – You Need To Be Religious About Working To These Numbers

Once you have your plan in place it is vital you stick to it, otherwise your power meter is nothing more than an expensive crank arm (or exercise bike).

That means your training will need to be specific to you . Which will result in lots of time on your own.

If the social element of training is a big deal for you then power meter based training may not be ideal.

I think that the choice ultimately comes down to whether personal performance or social training is the most important driver for you.

How About Racing?

This is where a power meter comes into its own. Pacing yourself across the 112 miles of an Ironman can be a daunting task.

With a power meter you can take all of the guesswork out of it, all you need to know is your FTP or LT number.

You then multiply by a percentage in order to fix a number that you should target for either average power (on a flat course). Or normalised power (for a hilly one).

The usual thinking is 80% is ideal to leave you fresh for the run. So if your FTP is 300w then you should target around 240w for the bike leg. This will leave you in decent shape for the run.

If you are a weaker biker then go lower, or a stronger biker go higher.

In Conclusion…

I have been using my power meter and Wattbike for 6 months now with a great training plan from my coach Dean.here is the effect it has had on my cycling VO2 max. This is from Garmin so probably not massively accurate but it IS comparable as it will always be equally inaccurate.

The difference made to my numbers by power meter training for ironman

I have, however, completely dedicated myself to running the numbers and working to them religiously.

Personally, I LOVE data and seeing progress demonstrated in the numbers.

Outside of that though, I have seen a huge difference on the road, I have NEVER felt as strong OR ridden as big average speeds as I have this year.

I am generally averaging 21/22mph now when across the previous 25 years it has been 19mph max.

Time will tell how this translates to race performance BUT so far it looks great.

SO ultimately YES power meter training for ironman athletes will definitely be beneficial but only if you use it correctly.

If you have any questions or would like me to write about anything else specific to power meter training please drop it in the comments below.

And as you got this far you may as well subscribe to get notifications when now posts are published 🙂

Thank you for reading as always 🙂