Listener Question - performing intervals

Wanting to quit but being able to hang on is a good criteria for the last rep of a set of intervals. I vary my high intensity sessions so I hit all the different above threshold energy systems. I have WKO and one of the advantages of that is it suggests 3 targets with specific minimum power outputs for improving my peak power, short, medium, and long duration, e.g. 1 minute, 5 minutes and 39 minutes. I try to do a couple of these/month.

Since your looking at 4x8, why not use your 32 minute power as a starting point and " solve the equation" from there?

I think it would be too low. My 32 minute power is below my FTP. Seiler’s suggested target power for his 4X8 intervals was the maximum power you can sustain for the set of intervals. I think I can sustain, though it won’t be easy, a little less than my peak 8 minute power.
I’m certain I can sustain more power for four 8 minute intervals than I can for one 32 minute interval.

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Sounds like a plan, only one way to find out. Then, reassess with after some data for the next session.

My understanding of the definition of FTP: power where a quasi- steady state of lactate accumulation and buffering occurs as determined by blood testing. Four mmol of lactate is the point I regularly here mentioned; everyone is a little different so your number and subsequent power by be different. Coach Ryan has much more actual experience with performance testing. I’m only regurgitating information I’ve heard.

From a practical standpoint, my understanding is FTP is one’s max sustainable power in the 40 to 75ish minute timeframe. See above paragraph about lab testing for the REAL number. So maybe 32 minute power is low in your mean max power chart.

Back to your question. Pick a power and see how it goes. If it’s too easy (even after the first interval), up the power; too hard drop it. The average power for all intervals, average of averages, would be a good start for the next session. Since we aren’t machines, the next session may be completely different based on external factors, life getting in the way.

Good advice. Pick a target range and see how it feels. Adjust as necessary.
What I’m trying to do is use the history of my past performance at specific durations to estimate my starting range for power at different durations. Most training plans assign the target power based on a particular zone, e,g, zone 5 or zone 6.
Since I have a detailed Power duration curve with my historical mean maximum power for any interval time, e.g 30 seconds or 25 minutes, I think I can use that data to arrive at a better initial estimate. I think 90 to 93% would be a good place to start.

Hi CCR_TX,

Really interesting conversation! I think this is a case where there are a lot of different answers and you’ll probably get all of them if you talk to enough coaches. Since this conversation started with my post about 4x8 minute intervals, I’ll give you my take on them…

First and foremost, the key question is what energy systems are you targeting? Depending on how you execute 4x8s, they can hit different systems. So the right execution depends on first answering that questions.

Personally, for my athletes and for myself, I use these intervals to train lactate clearance and to push up MLSS or basically raise your sustainable threshold power. With that in mind, a few thoughts:

  1. I’d be wary of doing them based off of 90% of mean max eight minute power. I say that because you really don’t know what that 8 minute number on your mean max curve means and what energy system it targets. The eight minute point on that graph may not be your true max eight minutes. For example, if you really push a short sprint, the shape of your curve will change and your eight minute power will decline. Yet pushing a big sprint doesn’t say anything about the energy system you are targeting with 4x8s. That curve is all about the general shape… taking a specific time point on the curve and using that power for any sort of targeted work is always a crap shoot.

  2. I’ve brought this up a few times, but I am always wary about targeting a specific power number. Really want to emphasize this - power IS NOT physiological. So, one day 280 watts may be perfect, but another day 300 or even 310 may be perfect. If you set an arbitrary power number, then some days you will be training right, some days it’ll be too high and some days it will be too low. So, when I give these intervals to my athletes, I give them a broad power range (that goes from about 90% of threshold power to about 105%) and emphasize to them that the power is the least important part in figuring out the execution.

  3. Because I use these intervals to raise an athlete’s sustainable threshold strength, I focus most on heart rate and RPE. I give my athletes an upper limit on heart rate that’s about 1-2 BPM above their threshold heart rate. They aren’t allowed to cross that line. If you look at the graph above that I used as an example of good execution, you’ll see that I didn’t hit the heart rate limit in the first interval. Generally I look to hit it in the second or third and then the rest of the workout heart rate should sit right at that limit without going over. The other thing I have athletes focus on is consistency. This is the only place I focus on power - the power should be the same across all four intervals. The exact power depends on how the athlete feels that day and what it takes to achieve the right heart rate curve.

  4. In terms of feel, these are not all-out intervals. The first one should feel a little too easy. By the last one, it should be a bit of a struggle to maintain the same power. But the intervals should never be exhausting. I tested how tiring they are and after a good execution, I was still able to hop into a race on Zwift and put in a solid race.

So notice, the focus is on heart rate (physiological response,) feel, and consistency. Power is the final factor and I tell my athletes that the right power is whatever allows you to accomplish the the first three.

The one last thing that I’ll add is approaching these intervals the way I’m recommending - “finding” the right power instead of pre-determining it - teaches critical skills. In races, you have to have the self awareness to know exactly how hard you can go that day. Especially if you are in a breakaway or time trial. My experience is that athletes who target a somewhat arbitrary power number fail more often than they succeed.

Hope that helps!

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