2 Q: decreased rpm and increased hr per interval and last minute step test proxy


I’ve noticed when doing say 3-5 intervals (of minimum 10 min in duration) at near threshold or at threshold (95-100%) I will start at relatively high cadence (100+) and notice it becomes considerably harder to hold at each progressing interval. In addition, my HR tends spike upwards as the intervals continue. My cooling is very good and I do realize that some of the HR spike could be from drift, but is this more a function of a relatively weaker aerobic system? While I like to keep my spin relatively fast at FTP and Vo2 max power outputs, I’m not opposed to varying the RPM from 85- 105. But, just curious about the physiological aspect(if any) of my question.

My second question relates to the TR step test to find FTP. Is the final minute (full completed minute) a proxy for Vo2 max power? In other words, the highest power during that test that I can hold for at least a minute, its that a proxy for 3-5minute power?

Thanks !

Per #2, I don’t think so.

If FTP = 230w,

  • VO2 Max = 120% x 230w = 276w

For FTP from Ramp test is Best 1-min power x 0.75,

  • 307w Best 1-m x 0.75 = 230w

So, 276w VO2 Max doesn’t equal 307w Best 1-min power from Ramp test.

I don’t see how those would align in any way. I have never seen a TR rep make a connection between the Ramp and VO2 Max, other than using the resulting FTP to calculate it.

I’ve seen cursory articles relating final minute to some variant of Vo2 max. But wanted to reach out here, possibly to Coach Chad for input.

Also, 120% of FTP is not an absolute for Vo2 max power proxy. So i’ve read.

Sure, nothing is absolute. But it is widely regarded as a decent approximation for many.

Even at 125% of FTP, that is only 288w in this example, and still well short of the Ramp Test 1-m at 307w.

I just don’t see a chance for a direct relationship as suggested in the OP. There is separation and need for some level of multiplication between them.

Thanks for your response.

I was not suggesting there was one, just interested to know from coach chad if there wss any at relationship between last full minute on ramp test and vo2 max power proxy.

Based on the initial question of a proxy (equivalent and such), I’d say the answer is ‘no’.

  • With the caveat that my calculations and understanding of the data points are correct.

There may well be a calculated relationship, but it is not a direct comparison.

Thank you. I wasn’t sure if you were Coach Chad from TR (podcast) or not.


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No, I am not Coach Chad Timmerman.

I include that info in my forum bio and clarify the difference in threads, any time I think someone gets us confused.

Coach Chad is @Chad on the forum.

Sorry, i thought you were!

I’m new yo TR and, quite ffankly, internet forums.

Any chance (when you get a moment) @chad could you respond to my 2 questions?

Much appreciated and very much enjoying TR to date. Almost finished SSB2 mid vokume

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Hi @86TDF. Regarding the Threshold intervals, by their highish-intensity nature they involve a hefty anaerobic component but are still predominantly aerobic due to their long-enough durations (anything over a couple minutes sees the majority of its energy turned over via aerobic metabolism).

But aerobic efficiency degrades over the course of any duration and suffers speedier degradation the harder you’re working. This is to say, the ‘oxygen cost’ increases thus requiring more O2 for the same amount of power as efficiency declines. As you become more aerobically fit, the decline in efficiency abates and you can last longer without elevating your breathing rate/HR quite as much.

You can also mitigate this efficiency decrease with recovery which is why I’m such a big fan of using short backpedal breaks to limit the rate of this decline with breaks that are too short to constitute true recovery (though that’s a very relative term) but long enough to mildly stave off negative effects like this.

With ramp tests, I’ve seen labs/coaches use the highest 3-minute average as an estimate of power at VO2peak, but that wasn’t our intention. With that said, feel free to take a look at your Ramp Test(s) and see if this bears out when you compare that 3-minute MMP with how you feel during different percentages of VO2max intervals.


Sent that before I added that there’s also the decline in anaerobic stores to consider.

Over the longer intervals, the anaerobic system dies a slow death. But since the power is held steady, the slack has to be taken up somewhere. Where would you guess the additional power comes from? The aerobic system, of course.

So as the anaerobic end of things slowly craters, the aerobic end of things is more heavily taxed, and as you’d expect, HR and ventilation rise, rise, rise.


Thank you so much for your time and thorough explanation !

Happy New year to you and the TR team !