Interval failures after FTP increase, how to manage?

I did a ramp test last Friday and saw a pretty decent FTP bump. I tried a V02 session last night (Mist +2) and made it through the first 2 sets (6 intervals). On each of the last 3 intervals, I failed about a minute or so into each interval. My HR wasn’t very high and I wasn’t breathing that hard, but just didn’t have the strength in the legs to hold the wattage. I ended up with each of the last 3 intervals with a ~30 second rest in the middle of them.

I think my FTP might be set a little high based on the ramp test, but I figured I’d leave it be for now and keep trying. What’s the best approach when you can’t complete the interval? Should I be adjusting the wattage down for the entire interval so I don’t need to stop or should I just keep the high target wattage and take mini breaks during the interval as needed?

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Can you be specific with what your ftp was before and after?

It may have been a bump from 286w (May 23) to 305w FTP (June 21), so 6% increase, assuming I am viewing the right profile.

Those are the right numbers. I didn’t execute the first test very well and I think it reflected a little low, but it couldn’t have been much over 290 based on some ftp intervals I did previously.

Legs feel particularly wrecked today, tried to do some SS work tonight and couldn’t even maintain it. Hopefully, just legs in shock from the hard effort last night. 100 mile gravel race on Saturday, so it’s rest until then and hopefully legs will be ready to go.

Could be a one off, we all have days when it’s just not happening for whatever reason. Would see how the next hard session goes, if you have a similar experience then drop your FTP by 10 watts and get a couple of good weeks training under your belt then review.

Re what to do mid-session when you’re struggling, for VO2 work I think you need to be aiming to complete each interval uninterrupted. If you’re struggling from the outset that means dropping the intensity by 5% (you can always put it back up later if things improve). If you get through the first few sets and then are struggling towards the end then another approach is just taking a little extra recovery between the last few sets.

For the longer intervals like Tempo and SS I think it’s fine to take a mini break by back pedalling during an interval, but not for the short high intensity work

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I think the key indicator here is that you weren’t breathing hard. That makes me think that either you were just having a bad day mentally/physically or maybe your cadence was too low and you just mashed your muscles into oblivion and couldn’t muscle through it any more.

VO2 work should be done with a relatively high cadence in order to put some of the burden on your lungs and make it more repeatable for your legs.

What was your cadence like during your intervals?

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Careful sticking to an FTP that is too high, it took me a while to climb back out of an overreaching hole. You may need to lower your FTP a bit.


Yeah, as mentioned above don’t change things on one session, try again and see how it is. Different days you can be on it or way off. Last Monday I felt tired and my legs just wouldn’t get above tempo, by Sunday I was flying and finished 3rd in a hill climb. This week I did 4x16 minutes above FTP on Tuesday then a super hard club ride last night where I did my best ever 10 minute power. Tomorrow might legs might not turn up!

Cadence was over 95 on all intervals, some into the low 100’s. I also did some weight work on Sunday and legs were still a bit sore, but that is my routine most weeks and I can usually get past it. I felt the same as I usually do starting the intervals, just much more fatigue as I got into the later ones. I felt totally rested and ready to start each of the intervals with a nice low HR, but fell apart quickly on the last 3. I think it’s just the stress of significantly higher targets and legs not used to it. If I struggle next week again, I’ll back FTP down a little.

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Yeah, that cadence seems fine. Chalk it up to a bad day, try to ensure you get some good recovery in when you’re off the bike and do your next hard workout as proscribed, it’s very possible this was just a one off.

I tried the same workout last tuesday with similar results. I even skipped my Sunday night weight-lifting session. I had to reduce the target on the last 3 intervals a few percent and was able to complete the intervals at the lower target. Just too much fatigue in the legs to push the watts at the end.

Despite the v02 interval failures, I can definitely feel that my FTP is up from a month ago, so something is working. 240 NP for 5 hours on Saturday was a personal best and I was still feeling strong at the end. I’ve got 2.5 more weeks before my “A” race (stage race) and plan to start cutting volume and doing some local group rides/races as I taper.

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