1st Vo2 max intervals

During the 20secs intervals I was always short by 4 or 5 watts. It was that I couldn’t physically reach it there was just a slight delay but even when I had it perfect it was still a few watts short. Found my 1st Vo2 max workout pretty tough but could probably have tackled another set of intervals, is this normal?

Yes and no, in other words…it depends.

The reason you felt like you could do another set of intervals is because you didn’t ride the previous intervals at target power. Even 5w makes a difference.

As an example, I just did 3 sets of VO2 intervals, the 2nd set I did at +5% higher target power. I bombed the first interval in the 3rd set & had to go back to normal target power.

The VO2max power range is a fairly large range, ~110-130%. As above, my ceiling might be 125% but yours might only 118%. If this is the case and you’re doing 120% intervals, that power will be very difficult to hit.

That said, Vmax intervals are hard and you have to go hard & dig deep, especially mentally. At the end, you shouldn’t feel like you could do more sets. Kind of the “gold standard” is 5x4min; if you can only do 4 yiu went too hard, if you can do 6 you didn’t go hard enough.

Lower the intensity by a few % and give them another go. You can train your power levels to become higher; it’s really hard work but it’s worth it.


I just posted this on another thread. Might be helpful?

Regarding VO2max efforts or anything above FTP…

In Training Peaks software they have something called FRC/FTP or Functional Reserve Capacity FTP. This is expressed in Kj and is the amount of continuous work you can do above FTP before fatiguing. Mine is very small IMO. Like 14Kj small. Not a lot of work there before fatiguing. MY FRC matches up pretty well with my power profile which shows (to the second) where a rider might be above average (W/Kg) average and below average. In my case I’m below average from like 13 seconds to 1 minute 54 seconds.

Long way of saying I suck at VO2. It’s a limiter. I know it and while I dread the workouts I look forward to them as well and am finding (in mid general build week 5) that my fatigue resistance is getting much better!

When anyone gets to FTP the tipping point is a very fine line that sways back and forth depending on cumulative stress how you rest, nutrition etc…some days we can tolerate more time over some days less. For better or worse I’ve learned that if a workout prescribes 120% FTP I start out targeting 115%. This seems to work well for me. If I feel ok I can sustain 115% for most intervals. If good I try for 120%, and if bad I just try and keep it in VO2 range. Not recommending it but, I’ve had a good response. Besides that I’ve found (for me) a little longer warm up helps. And a second fan from the side hitting my torso and legs keeps me much cooler which may be the game changer.

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Can you be more specific about both the % of FTP and the overall power target for these intervals? 4-5 watts is much more significant at lower power numbers than it is at higher power numbers

Also, to be sure I’m clear - are you using a smart trainer in erg mode? It sounds like you are based on the delay you reference, but want to make sure I understand

Intervals were 20secs on at 120%ftp which was 255watts and 30 secs off in erg mode. Captaindoughnutman = No matter what I done I was always short a few watts but it wasn’t that I couldn’t hit it physically, tried high cadence a few seconds before interval but still was short.

Just to be clear, once I get to 255watts I can keep it no problem but it’s just the start and end of the 20sec interval that I’m losing a few watts.

I find ERG mode isn’t the best for VO2max intervals for me. There’s the lag issue for sure, and also when I start getting fatigued my power gets erratic (my cadence must be erratic) and going above/below my target. I need singleminded focus to complete VO2max anyway, so resistance works well for me since I am already so focused on the task that manually dialing in my resistance works well with no extra effort.

I tend to do the first few in erg mode to get through on target. Then the last couple I do in resistance mode so that I can push a bit higher if I have anything left (unlikely) or lower it a bit so that I can complete.

Yeah the difference at 255 watts is not insignificant…that said, personally I don’t stress about this as for me being within +/- 5 watts is pretty immaterial. Everyone has different levels of OCD on this though. As you can see in the screenshot below from my last short duration interval workout I’m rarely at an exact match


Those were 15 seconds in duration - for me being that far off target is fine, all part of the process. Even with manual mode, no power match, etc…it is really hard to exactly hit a target for that short of a duration. The meaningful piece (in my opinion) is getting close

I’ve done several years of TR plans and it is always hard when you are transitioning into the VO2max stuff You’ve just spent 12 weeks doing mostly sweet spot without any high power stuff. I think this is just inherent in any structured base, build plan so it is not a bad thing, just something you need to be aware of. This is made even more pronounced by the fact that most of us are doing this base work in the winter with little or no outdoor riding so we are not even getting those short random 120%+ spurts that come on even the easiest outdoor rides much less what you’d get in terms of higher power bursts on even the easiest group ride.

On top of the fact that it is just plain hard to have to crank out %120-140% of FTP, you have the added challenge that the snap you need to go from the recovery power to the VO2max target power quickly is hard and you are probably not quite up to snuff on that aspect of your riding at this point in the season. it will come as it always does.

I don’t know if this helps, but on my Magnus in ERG mode, I build up my cadence a couple of seconds before the intervals start so that I’m at my target wattage and then hold on for the interval.

I assume that you mean that your reported power vs target at the end of the interval always falls short which in that case it could be the lag of your trainer to apply and report braking power. My trainer can take up to 5-6s to catch up. The bigger the jump i.e recovery level to 120% FTP the worse the “miss” as is the shorter the interval. I have “missed” targets by 30,40,50W on short <20s) intervals because my trainer simply can’t get there fast enough to average the transition out even though I can hit the actual power output. There are ways to minimize it but I am too lazy to get out of Erg mode and have simply decided to accept it.

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Try experimenting with your Power Smoothing settings too, just an idea

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