3 minute FTP intervals with very short rests?

Any thoughts on this one? Whenever I’m doing FTP-type intervals (8 minutes to 1 hr.), it always seems like the first 3 minutes of the interval is the worst. More accurately, the first 45 seconds are almost easy (I assume because creatine phosphate is being used to fuel the effort), but from 45 seconds to 3 minutes the interval is always the hardest. After 3 minutes, though, I seem to get into a “groove” and I can usually keep going almost indefinitely (up to an hour) at that effort. In that context, I thought that it might make sense to do 3 minute ftp repeats, with a very short rest interval (probably @ 50% ftp to maximize lactate clearing) of around 30 sec. to 1 min. (to allow for rebuffering of creatine phosphate?) and then go again with the 3 minute ftp interval - essentially until exhaustion. The aim of the workout would be to train that first 3 minutes, because, I assume there is something important happening during that time based on my subjective feelings.

Any thoughts?

For reference, I’m 54 yrs. old. 1 hr. FTP is 256 watts. Weight is approx. 62kg. WKO5 says my VO2Max is 64 @ 324 watts (I’ve been as high as 73 @355watts).

  • Mike in Czech

Hi @MikeinCzech, welcome to the forum! So do you have any recent files or workout profiles that you can post to this thread? That might help to see how you’re approaching the workouts, etc.

Your approach of 3 min intervals with 30-60 seconds rest is approaching @trevor’s famous 5x5 intervals. Some of his workshops and past podcasts highlight the way to approach this session, so I think you can take that and apply it to your 3 min and longer efforts.

Coach Ryan

The 2 workouts above are from today (the top one) and yesterday (bottom one). Today’s workout was 5x9’@105%FTP with first 30"@VO2max, then 60’ @ endurance heartrate, followed by 20’@tempo HR, finishing with 2’@110%FTP. Yesterday I did 5x3’14" @FTP/FRC threshold with 3’14" RBI. I chose the power/FRC graph in WKO5 as I think that it gives a good sense of how taxing the intervals are via the slope of the falling FRC line. As you can see in yesterday’s ride, for the first 2 intervals I maxed out my FRC and had to lower the intensities for the last 3 intervals.

On today’s 5x9’ workout, I switched from my TT bike on a Feedback Omnium trainer after the FTP intervals to my CX bike on Elite Real E-Motion rollers for the endurance part of the workout. Yesterday’s 5x3’14" workout was on the TT bike on a TACX NEO in Erg mode.

Hi Mike,

Interesting thoughts and files! I just read this so giving you my immediate thoughts. First, to your question about what’s going on when you’re not feeling great in those first few minutes. I think you pretty much identified it. During the first 45 seconds to a minute you’re relying heavily on anaerobic sources such as PCr and glycolysis. It takes time for your aerobic system to fully ramp up. So you have that period of time from about 45 seconds to 3 minutes where you can’t rely as much on anaerobic metabolism, but the aerobic system isn’t firing on all cylinders yet.

I think that’s why I haven’t seen many coaches use three minute intervals. I certainly avoid them. As you know, I’m big on maximally targeting energy systems. So, from my perspective, a three minute interval in many ways targets the transition between energy systems and as a result, targets neither energy system well.

I personally prefer one or two minute intervals where you can go hard enough to really hit those anaerobic energy systems and drain the FRC, or something longer to focus on the aerobic pathways. For me, a 5-8 minute interval with short recoveries is about right for the latter. A three minute interval, because so much of the time is in the transition, isn’t hard enough to really hit the one energy system, but also not long enough to work the aerobic system.

That said, the question is whether there is a beneficial adaptation that occurs by targeting that transition between energy systems and I actually don’t have an answer for you on that. I haven’t seen a specific study addressing it.

One other thought to share… looking at your files, that’s A LOT of high intensity work to do over two days. And it does look like you were struggling a bit to maintain the quality. Whatever you choose to do, I’d recommend spreading it out more and making sure you do it with the highest quality that you can.

Hope that helps!