# Hi Guys - can someone explain to me what Strain is?

I am struggling to understand what Strain value actually means physically. I think I get the handwaving explaination: it is the work you do close to To MPA. However, I would like to see the actual mathematical formula, or at least dependence of strain on all the values that are included in calculating strain. O just started with Xert and i see that some of my workouts show strain of hundreds of thousands of kJ. What is the meaning of that??? Thanks!
Michal

Check our glossary and blogs. There is a lot written there.

Hi Armando,
Thanks, I went through the blogs and glossary but unfortunately the info there is rather handwaving. I would like to understand why my strain in some of my workouts is as high as hundreds of thousands kJ. So, I am after the understanding of quantitative description of strain (as opposed to the intuitive understanding).
Thanks,
M

Hundreds of thousands?

Hi Armando,
Yes, that is why I am very confused and I am trying to understand how strain is quantified. In my “progression” graph when I choose “strain” the “weighted average daily work (kJ)” is shown as hundreds of thousands. I see some of my activities (all about 1 hour) with strain of 250 000 kJ. I do not understand what strain actually is and whether this makes sense or not… It may well be a wrong label of the axis (kJ instead of J). Still, it would be great to actually understand how strain is calculated.
Thanks,
M

Yes. That’s an error we’ll have to fix. The mathematical formula for strain is not being disclosed at this time. We provide substantial information on the principles on which it is based however. The principles are sound – the greater the effort near MPA, the greater the strain. When strain is normalized to 100 for 1 hour at TP, it acts very much like the stress scores in other programs. The main difference is that you can accumulate more strain when MPA is lower due to fatigue. Hence 1 hour constant effort at just below TP is just below 100 but a variable effort at the same power, is much higher than 100. In fact, will likely be impossible for some due to the added strain and difficulty.

Thanks Armando. Much appreciated.
Michal