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Dear Hans and Ron,I have read your book in detail and your latest articles published in Dutch on the new Stryd power meter (through translation) and in particular your treadmill and intervals experiments. I have the new Stryd; and on 29 September I am running the Berlin marathon (nearly flat for the whole distance so hills are not a factor) and only a couple of weeks ago I did a 32.2k race using the old Stryd and I have the wind and other details for that and so have recent personal data for a comparable long distance. If there any experiment concerning this real life situation you might be interested in collaborating on that would be helpful, please let me know: you could use the email address I’ve supplied to contact me, if you wish. If this is not helpful, it’s no problem. Kind Regards and Best Wishes and Good Luck for your own training, Brian
Dear Hans and Ron,
Congratulations on your book, and on your work, from me as one of your English fans. I hope your training and running is going well.
I thought it would be useful to draw to your attention a two part analysis done by a Mr Ian Williams, published in our Guardian newspaper (link below). Mr Williams did a statistical analysis of 1071 marathon runners who logged their training data on one of the running websites in the UK. He found that the Riegel formula, reliable for shorter distances, broke down as a reliable predictor of marathon performance: 95% of the runners analysed were outside its prediction. Hans, I think you say, you yourself fall outside the Riegel predictions in the case of marathons. Mr Williams also sought to analyse, from the website’s data, training factors which were helpful enabling some of the runners to come close to meeting the Riegel prediction, or not, as the case may be. It may be food for thought as to whether, in the case of non-elite, runners, it might be reasonable to adopt a two exponent approach: Reigel for shorter distances, say up to 1/2 marathon, and another exponent for a distance such as the marathon where the risk of fatigue or glycogen depletion is a heavily influential factor. I think you’re already thinking to some extent along these lines in the book. For interest, therefore, here is the main link from which other links can be found to explore this topic: https://www.theguardian.com/lifeandstyle/the-running-blog/2018/feb/15/an-updated-formula-for-marathon-running-success
Your online calculator has been great for finding out what goals I should be aiming for, now that I’ve finally started to run consistently.
We’re glad to hear that,Zak!
All the best with your running!
Hans van Dijk
Running in a group will help to spend less power against the wind. But what, if the group runs a little bit faster than my race-pace? How many seconds faster should I run to stay in the group? And at which difference should I leave it to keep my pace on my own?
This is a very tricky aspect. The advantage of less power depends on your speed, but is only 1 or 2 % for recreational runners.
Of course you need to avoid going too fast as this will create big problems. In my experience you need to be cautious. On a lucky day you will find a group running at your pace, so you can follow them while saving energy and power. At the end of the race this will pay off and you mau achieve a PB.
Best of luck,
Hans van Dijk
Your book and information at this website are THE reference for running with power besides Jim Vance’s book. I really appreciate that finally the ‘full physics’ of running are explained in a comprehensible way in one reference.
However, I wonder about your assumptions in the online calculator regarding FTP and VO2max, understanding that you derive VO2max from FTP by the factor of 0.072, here.
I end up with a calculated FTP that agrees well with my STRYD CP, but VO2max (using the aforementioned factor) does not agree with that calculated by the Jack Daniels formula, whereby the latter actually provides me with very good estimates for my duration-dependent race paces.
Should your calculator not rather use the factor 0.081 to derive VO2max from FTP (as stated in Chapter 75 of your book) instead of 0,072? At least for me, this provides a VO2max estimate which is closer to that calculated by the Jack Daniels formula (-> realistic race time estimates).
Thanks your comments and kind regards,
After doing some further testing with the calculator and my own calculations, I understand that you are scaling the factor to relate VO2max to FTP by 10 min to 60 min, even though race times provided by the user are likely always different.
Hence, you receive different VO2max values for race paces that actually perfectly match the calculations after Peter Riegel. Scaling the factor by race time vs. VO2max time solves this issue from my point of view. Consequently, each realistic pace for a given race distance would provide the same VO2max value.
I am looking forward to your comments and would be grateful about more details on your calculations.
Thank you for your compliments and question.
I am glad see that you have figured out the answer by yourself already….
Indeed, we calculate the VO2max from the given race pace for a given distance.
The relationship between FTP and VO2 max is the factor 0.072.
This can be easily understood by the different duration times (FTP= 1 hour and VO2 max= 10 minutes, the Riegel ratio is 0.88).
The relationship between FTP and VO2 is theoretically a factor 0.081 as explained in chapter 75.
So the VO2 at 1 hour FTP/0.081, consequently the VO2max at the FTP is FTP/(0.081*0.88) which equals FTP/0.072
I trust this will be clear now?
Thanks for the prompt reply, Hans.
I have purchased a hard copy of the English translation from Amazon and I’m finding it absolutely fascinating, so thank you for taking the approach you have!
I find it a bit large and heavy to read in bed, so I wondered if you did a reduced price ebook or PDF version for people who have purchased the hardcopy? I could then read it much easier on my iPad.
Thanks again, fantastic work,
Thanks for your compliments, Chris!
I have submitted your question to our publisher Meyer& Meyer
Unfortunately, they have informed me that due to legal and other matters, they cannot offer you a reduced price for an ebook.
Hello Hans and Ron,
Thank you for the book! I’m enjoying reading it. I’m not following a following in Chap 20 where you relate FTP and Vo2max. Vo2max is expressed in ml/kg/min and DeltaG in KJ/L of O2, it seems than when doing the conversion, we should end up with Vo2max in L/kg/Min vs. ml/kg/min? could you help me there? thx L
Thanks for the question and we are happy that you enjoy reading our book.
The answer is that delta G is indeed expressed in kJ/LO2 which is equivalent to J/mLO2.
So you can convert the VO2 max in mlO2/kg/min to 0.25*19.55J/kg/min.
As 1 Watt is 1 J/s, you also have to divide by 60 (seconds in 1 minute) to come to Watt/kg which is the unit of the FTP.
Hans van Dijk