Turbo Training with FTP and LTHR

Turbo Trainer throughout the winter can become a little dull (although I quite enjoy it!). So, to spice things up I’ve been following one of the TrainerRoad training plans. The plans themselves are OK, although by necessity they are a little generic. That’s fine at this time of year for me though as I’m only really doing fairly generic base level training anyway so they suit me at the moment. Once I’m training a little more specifically for sprint distance triathlons I shall stop following them but hopefully by then the weather will have warmed up and I’ll be keen to get out on my bike in the real world anyway.

The way TrainerRoad works is that you do a couple of 1 hour tests that are designed to determine your Functional Threshold Power (FTP) – This is the maximum power output that you can sustain at a steady state for an hour. The tests themselves aren’t just one hour at maximum as that is very hard to do, instead they are shorter intervals at above FTP from which their algorithms can calculate your predicted 1 hour FTP. Even so, pacing properly during these tests is difficult as you have to try to go all out throughout the intervals and keep the effort and power output for each interval about the same.

After my first round of tests my FTP was 250 Watts. Each TrainerRoad workout is then scaled accordingly. So, if your FTP is 250 Watts and the workout calls for long intervals at just below FTP, these will be done at around 230-240 Watts. If your FTP was higher then the workouts would call for higher power outputs. Similarly, if your FTP is lower then the workouts will be scaled accordingly and will be at a lower power output.

As I started doing the various workouts in the plan I manually adjusted my FTP upwards as they seemed a little too easy. I know this was supposed to be base level training and so they shouldn’t be too hard, but I also knew that in all honesty I had some left in the tank during the tests so my FTP figures from these would have been a little too low. In the end I settled on an FTP setting of 267 Watts and have been training quite happily at that level for a few weeks.

As I changed from the Base Level I to Base Level II the plan called for another test. This time it was an eight minute test – A 20 minute warm up followed by two all out 8 minutes efforts with a 10 minute rest between them. I went quite hard all the way through hoping to put in a quality test, but as you can see from the trace below I obviously had a bit left towards the end as I was able to put in a sprint finish on the last 8 minute interval. I was finished by the end of that though and couldn’t have given much more. The TrainerRoad software then worked out my new FTP, it was quite a lot higher than before, a massive 30 Watts more in fact at 297 Watts.

8 Minute Test

8 Minute Test

Before I go on I should make a note about the numbers. The actual numbers are based on virtual power (I don’t have a power meter) so in some respects may be inaccurate. If you compare this with a power meter or even another turbo trainer set up then the actual figures may not correspond. That doesn’t really matter, what does matter is that I’m able to repeat these tests on the same equipment and get closely approximating results. Comparing them with other people or other equipment isn’t the goal here, tracking my progress and providing myself with repeatable workouts at the same intensity day after day is.

Despite this, an FTP of 297 Watts doesn’t sound too far off the mark and the fact that it is higher than it was is in some respects a good thing. However, it will also mean a whole new era of pain and suffering! I’d been happily doing the TrainerRoad workouts based on an FTP of 267 Watts, now that my FTP figures have increased, all of the workouts will be graded correspondingly harder as well. The first of which was a workout called ‘Lamarck’. Not only was it now based on an FTP 30 Watts higher than before but it was a particularly mean looking workout as well. Four 10 minute intervals smack bang on FTP. Until this session all the base level workouts had been slightly below FTP now I had to do four 10 minutes intervals at FTP, and a higher FTP at that.

I was sort of looking forward to though so jumped on the turbo trainer and gave it a go.

I didn’t think I was going to make it. The first interval was hard but I got through it. The second one was harder still but I hung in there and made it. My legs were burning by the end of the third, but now there was only one more to go, I could do this, nothing would stop me now. I made it through the fourth as well, it was hard work and I was pretty tired by the end of it, but I’d made it and what a good workout it was.

Looking back at the stats from the workout I actually improved a little on each interval as well and was a little above my FTP target of 297 on all of them.



Average Power (and my heart rate) for each of the intervals was as follows:

  • Interval 1 – 302 Watts (141 bpm)
  • Interval 2 – 303 Watts (148 bpm)
  • Interval 3 – 303 Watts (151 bpm)
  • Interval 4 – 308 Watts (155 bpm)

I’m quite pleased with that!

Talking about my Heart Rate, during the tests TrainerRoad also provides you with a Lactate Threshold Heart Rate (LTHR) reading. In essence this would be your average heart rate during an hour long maximal effort. It’s useful if you are training by heart rate, but isn’t as good as using Power or even Virtual Power to scale your workouts. All the same, it was interesting to see that according to the tests my LTHR was only 136 bpm. This seemed pretty low to me despite the fact that the tests themselves felt hard. My heart rate is always pretty low compared to most peoples, both whilst resting, during exercise and as a maximum so I always expect it to be low, but this seemed low even by my standards. It could be right, but I’m sure at a maximum effort for an hour it would be higher than that.

2 Responses

  1. Avatar forComment Author Alan says:

    I’ve now done a few more sessions at this new FTP level and I have to say it is just about spot on… Each session has been hard. When I first start them I don’t think I’ll finish them but I hang in there and just about make it, usually with a bit of a flourish at the end.

    I could probably make it a little harder but then I might not finish them, but for me, it is better psychologically if I do make it, even if I have a little left in the tank at the end. Better that than not completing the session which just ends up feeling like a failure as far as I am concerned.


Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Avatar forComment Author

Alan Cole

Alan is a Freelance Website Designer, Sports & Exercise Science Lab Technician and full time Dad & husband with far too many hobbies: Triathlete, Swimming, Cycling, Running, MTBing, Surfing, Windsurfing, SUPing, Gardening, Photography.... The list goes on.

You may also like...