How Should VO2 Max Feel?

Anyone have feedback on how VO2 max intervals should feel?
I finished the half distance low volume base plan last week and I’d been upping my FTP throughout base as I kept being able to complete the workouts fairly easily. The long SS intervals are normally medium hard, but doable, however I rarely feel like I am panting or breathing hard on the bike.

The last 4 weeks of base did have VO2 max Intervals, but I always feel like muscle fatigue knocks me out before any sort of breathing or HR limitation. Am I doing something wrong or is muscle fatigue limitations without feeling like I am dieing for air an indicator of hitting my V02 max?

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I always find it’s muscle fatigue that stop me. I just can’t hold the power and have to back off.


like death. it should feel like death


If I have to bail on VO2 workouts it is usually on account of muscle fatigue, and usually because I haven’t fully recovered from a previous workout.

One thing that helps is a high cadence- above 100rpm does the trick.



Next question :stuck_out_tongue_winking_eye:


Not sure where I read it or who said it, but it was a pro who claimed VO2max intervals felt like you are drowning. I agree…to a point.

If you’re slogging out 5-6 Classic style 3-5min 120% intervals…yeah, expect death-like symptoms. However, if you’re into doing these new fangled hard-start declining power intervals (Rattlesnake) or even longer & lower intervals (8min @110%), then you might get away with simply feeling really gross instead of almost dead. Each person has their own personal point of failure — legs, lungs, heart, head…

Happy pedalling! :grin:


And you should be able to smell the sulphur. “Abandon all hope, ye who enter here”.


If you look up and theres a tall black robed dude with a scythe…back off… :crazy_face:


if you’re fresh enough to do the workout, they really shouldn’t feel that bad. you should have the adrenal reserves to punch them out – I find that the worst sensations are right after you stop the interval and the endorphin+adrenaline flow cuts back.

That’s outdoors.

I don’t do any zone 5 interval over two minutes long indoors anymore – not after a full day at work. Indoors, they’re just awful.


I’m the exact opposite I love to torque it out around 85rpm when I start to fatigue.


on the flats, I try to do the VO2 intervals at 100rpm – I get too bogged down to get the power, otherwise

uphill is a different matter. Unless the grade is over 8%, I just keep it in the big ring and stand, grinding away at 60-70rpm. Strava says I’ve done my interval hill 1265 times over the years. I’ve tried all kinds of cadence and gear combinations, but the best way for me is to stand for 2:30 or more of the 4min climb and just muscle the gear. pretty hideous, really.

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For me VO2 intervals feel like I’m sprinting with my mouth taped shut.


It will feel different for everyone. It also can depend on the type or session. 30/30’s feel much different than 3-4 min intervals.

I find the longer intervals to be much more painful in terms of lactate build up, whereas short intervals give me rest sooner, but I am hitting higher ventilation because there almost is no rest.

They all suck in their own special way.

I know I’ve had a good VO2max workout if I can get to the last interval and then I just kinda blackout for however long it is and not even remember what song was blasting on my speakers. When that happens, I know it was dialed.

If that happens before the last interval, it was too hard. If that doesn’t happen, it wasn’t hard enough.


Similar for me, but a panic about my breathing upon completing a set… that I may not be able to breath enough to catch my breath. Mild scared feeling and almost immediate question of why the heck I do this to myself… on purpose :stuck_out_tongue:


When if you was doing it on the rollers you would fall off due to a near death experience.

Shorter ones (like 30s or 1min) : I’ve got this…!
Longer ones : They’ve got me!!

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VO2 max workouts are meant to make you work close to your maximum heart rate. Try to keep a high cadence(>100RPM) and it might help.

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I am midway through half distance low volume build phase and almost mirroring what you describe Owens nearly killed me this week!. I can manage just about everything apart from the 3 minute vo2 max/110-120% intervals. I usually manage the first 3, but struggle from then on. One of the TR podcasts mentioned back pedalling for 10-15 seconds (which shouldn’t impact interval quality or training gain) which I’ve tried but never seems long enough. I’ve dialled down intensity to 90% of the target for up to 1 minute and this seems to help and I can the finish the last couple at the prescribed target power. Hopefully I’m still getting the performance benefit. Or am I?

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I think so. Check out the post here:

and maybe more usefully, his second video:

If you look at the example graphs, some are solidly following a target, but most are starting way harder than target and dropping to sustainable power. I’m thinking personally never to do these in erg mode and just aim for the heart rate zone, as per his description there.