[FT(20min)-5%] = 2 x 20min @ (x)%FT ??

cbjesseeNH said:

Or, in English, if I have established my FT via performance on a 20min test (minus 5%, a la Hunter), can I calculate what percentage of my FT would be an equivalent performance in 2 x 20min intervals?

Would it be as simple as determining the TSS for the 20min test and then solving backwards to find the %FT for two sequential 20m intervals (with 5m rest between)?

My intuition says no, but I'd appreciate enlightenment.

I am not 100% ( 😄 ) certain that I fully understand your question, but perhaps this will help: the power that you can routinely generate during long intervals or efforts done as training will typically be equal to ~100% of your functional threshold power.

To put it another way: whatever your functional threshold power happens to be, if you rest up a day or two and then let 'er rip during an all-out 20 min effort, you'll be able to generate 3-9% more power than you could during, say, a 40 km TT.

acoggan said:

To put it another way: whatever your functional threshold power happens to be, if you rest up a day or two and then let 'er rip during an all-out 20 min effort, you'll be able to generate 3-9% more power than you could during, say, a 40 km TT.

So what I'm asking, in a failed attempt to eschew obfuscation:o , is once I know the power I generate on the 20min effort, and adjust down 3-9% for the 40kTT correction, I now want to predict the watts I can maintain for 2 x 20min efforts. If I know the TSS of the 20m test, do I assume TSS/2 for each of the 2 x 20min intervals and solve for Watts?

cbjesseeNH said:

So what I'm asking, in a failed attempt to eschew obfuscation:o , is once I know the power I generate on the 20min effort, and adjust down 3-9% for the 40kTT correction, I now want to predict the watts I can maintain for 2 x 20min efforts. If I know the TSS of the 20m test, do I assume TSS/2 for each of the 2 x 20min intervals and solve for Watts?

You may be making this harder than necessary. I ride my 20min L4 intervals at 90% of my 20min MP. I find that I can complete two (or more) 20min L4s at this intensity with a short rest and in fact the rest is more symbolic than anything. It so happens that this is also right in the middle of Andy's recommended L4 range. Specifically, my 20min MP is 108%FT and therefore 90%MP is 97%FT, or right in the middle of the 91%-105%FT L4 range. I think that's pretty typical. Now, 90% sounds like a high percentage of MP. But, if you think about it, you can do ~100w with basically no effort at all. So, if MP is, say, 300w, this is really the sum of two parts: 100w for "free" and 200w of effort. So, taking 10% (30w) off the top is really equivalent to taking 15% off the top of the "effort" piece.

cbjesseeNH said:

So what I'm asking, in a failed attempt to eschew obfuscation:o , is once I know the power I generate on the 20min effort, and adjust down 3-9% for the 40kTT correction, I now want to predict the watts I can maintain for 2 x 20min efforts.

You should be able to do 2x20 efforts at ~FT, so forget about using TSS to back into the calculation. Whatever you estimate your FT to be, use that as the interval power for your 2x20 efforts and fine-tune from there.

cbjesseeNH said:

So what I'm asking, in a failed attempt to eschew obfuscation:o , is once I know the power I generate on the 20min effort, and adjust down 3-9% for the 40kTT correction, I now want to predict the watts I can maintain for 2 x 20min efforts. If I know the TSS of the 20m test, do I assume TSS/2 for each of the 2 x 20min intervals and solve for Watts?

No need to invoke TSS, etc.: unless you're especially tired or are doing more than the typical 30-40 min of total training at this intensity, you should be able to do your level 4 efforts at ~100% of your functional threshold power. Some days it might be a little more and some days a little less, but on average that's about where they will fall.

If you find yourself fading significantly towards the end of such a training session, then you've probably attempted to bite off more than you can chew (at least for that day/given the conditions...for example, if it's hot and you're not fully acclimatized, your power will of necessity be low). OTOH, if it doesn't start to feel "annoyingly hard" towards the end of the session, such that you have to concentrate a bit to maintain the effort, you're probably not doing them hard enough to obtain maximum benefit.

Having just tried 2 x 20m at FT (5min rest), I found my cadence hard to maintain 10-15m into the 2nd and couldn't make the last 5m on a Computrainer erg ride.

It sounds like the advice is to back it down 5-10%, see if it was an off day, and work my way back up.

... and maybe the TSS calculation questions are just my quantitiative self getting a bit excessively anal. I stirve to be just anal enough! 🙂

cbjesseeNH said:

Having just tried 2 x 20m at FT (5min rest), I found my cadence hard to maintain 10-15m into the 2nd and couldn't make the last 5m on a Computrainer erg ride.

It sounds like the advice is to back it down 5-10%, see if it was an off day, and work my way back up.

Sounds like a good plan. However, if you routinely find that you can't complete the workout at your functional threshold power, you probably need to reassess things to see if perhaps you haven't overestimated it. IOW, since the best predictor of performance is performance itself, the inability to do 2 x 20 min at 100% of your functional threshold power in and of itself says that you're really attempting to train at >100% of your functional threshold power.

cbjesseeNH said:

Having just tried 2 x 20m at FT (5min rest), I found my cadence hard to maintain 10-15m into the 2nd and couldn't make the last 5m on a Computrainer erg ride.

It sounds like the advice is to back it down 5-10%, see if it was an off day, and work my way back up.

... and maybe the TSS calculation questions are just my quantitiative self getting a bit excessively anal. I stirve to be just anal enough! 🙂

If I'm reading your numbers correctly, you attempted to do the set at 95% of your 20min MP. My approach would have led me to a slightly lower target, specifically 90% of my 20min MP. I'll be curious to see where you end up.

Thanks y'all. I'll ride and report back.