Spencer +2 Blowup

I did spencer +2 this morning first thing. 1/2 banana and some water. Not a great night sleep, but this is the only time I had today.

Warm up and first interval went fine. Under coach Chad advice, I upped the intensity +3%. Blew up 1:30 into the next interval and got off the bike ready to call it a day. 10 seconds off and decided to jump back on and backed off to original 120%. After that interval I backed off to 115% and finished last 3 intervals.

-Are VO2max workouts best left for afternoon (better fueled and ready to “work”)?
-Should I have just bailed and done the work later?
-Is there still a decent benefit to this workout @115%
-Does VO2max raise at the same rate (parallel with) as FTP?

Thanks. I’m in the last week of SSB2 Mid before taper week, and I would like to be able to start build plan strong.

  1. Depends, if you can fuel well and get your head in the game in morning then it should be fine. Personally i always perform better in the afternoon/evening when it comes to over threshold work, but plenty of people make morning intervals work well.

  2. No by the sounds of it you did fine.

  3. Yes absolutely, VO2 power as a percentage of threshold is very personal and working at 115% of threshold for 3 minutes x 6 times will be super beneficial. Remember that these sessions are meant to be really hard, 115% isn’t a walk in the park even though the intensity is a bit reduced. Maybe hold back on upping the percentage next time, doing 3 minutes at 123% is super taxing, might be able to get through more intervals at 120% if you don’t do this.

  4. I don’t believe it does, I believe I am correct in saying that your VO2 max power is your aerobic ceiling so to speak, and it will peak out a lot sooner than your FTP (someone correct this if I am mistaken) and as your aerobic system becomes more efficient your V02 max power and threshold power will converge on each other. Tony martin’s threshold is 95% of his VO2 max power (pretty insane), this also highlights how personal VO2 max intervals are.

Working capacity is as important as absolute power so you can extend the amount of time that you can work at these higher powers,which is what you are doing when you do the intervals at a reduced intensity such as 115% and why it is still really useful. In a road race the guy who has a lower 5 minute power but can do it 6 times will almost always beat the guy who has a higher 5 minute power and can only do it once.

Try some sessions with more rest and absolute power targets to build power (matthes+3 or something like that), and do sessions with reduced rest periods and longer intervals at lower percentages of threshold (Baird or Ainsle type of sessions springs to mind) to build capacity.


On your first question, many of us have no choice but to train early in the morning (there’s a few threads on the topic around here) - so yes, you can do them in the morning. Are they easy? That really depends on the individual. I find VO2max sessions easier than threshold, but some find quite the opposite.

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Yes these intervals are about working at aerobic capacity, and different people like myself can benefit even when dialing down to 108-110%.

VO2MAX intervals only require the minimum amount of power to quickly bring your body to a state of max oxygen demand (“peak aerobic uptake”). The only way to know for sure that you’ve reached peak aerobic uptake is to wear a mask that measures oxygen consumption.

There are different types of vo2max intervals and some are easier for me than others. There have been studies where a state of max aerobic uptake is reached using say a minute or two of high power, and then reducing power to stay in that state for 15-25 minutes. One participant was able to drop below ftp power and still get all the benefits! Highly individual.

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janerney pretty much hit the nail on the head with his reply. The only thing I can add—because all of my workouts are done early—is that you should have enough glycogen on board from the previous day’s meals to complete most, if not all, 60 min workouts. I like to have a higher carb snack before bedtime (1/2c oatmeal with some berries or a slice of toast with nut butter)

A little pre-workout snack that is easily digestible and contains simple carbs won’t hurt, but I find that sometimes doing work at such a high intensity doesn’t work well with a stomach containing food. Keep the intake simple, banana is great.

I think people on this forum really overthink VO2 work and get psyched out. It’s really hard work, there’s no getting around it, popping a bunch of gels pre-ride probably isn’t a formula that’s going to make the efforts easier, coming into them well-rested with fresh legs will though. It’s ok to drop the percentage, 120% is not the be all end all in terms of getting a benefit. I find 115% over periods longer than 2 min very demanding.


Indeed - but I still find them not quite as bad as 200 or 400m running repeats on the road or track. Maybe the intensity was higher (although I don’t see that reflected in HR tracks), but I don’t get the fish-out-of-the-water feeling on the trainer that I got running.

Blimey, if that is ‘blowing up’ then you’ve never really blown up :joy: Sounds like you did a v tough workout really well. I do nearly all vo2 work with intervals at 2 mins or longer at 115% rather than 120%. You did great, don’t sweat it

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So I programmed Spencer +2 for myself this week after most of a week off due to illness and travel, and basically skipping a week of Sustained Power Build LV. I made it through the first two intervals, blew up on the third and bailed, doing Volunteer for the last 30 minutes.

Spencer +2 is no joke, man. I nailed it the first time during SSB2, but that was after six full weeks of complete compliance without a newborn interrupting my sleep. Based on my limited experience with that workout specifically, but over time with VO2 work, answering your questions:

  • I do VO2 workouts in the morning without much issue, but that’s when I can get them in. I just do my best to make sure they’re properly fueled the day before, and err on the side of carb overload during (gel and sports drink if required). Caffiene helps too.

  • Your call. Don’t get hung up on it.

  • You would still get most of the same benefit at 115%.

  • Nope. Chad’s analogy of filling up a cup is a good description. FTP is how much the cup is filled, VO2max is the capacity of the cup. They’ll grow together, but not at nearly the same rate. For me, my FTP has gone up quite a bit this season, but my perception of my pVO2max hasn’t changed all that much.


This could be the only consumable that could actually make the workout feel “easier”.

Problem is, the espresso machine makes a racket to wake the dead, and everyone is sleeping when I go train… so unless I want to lose some serious wife-miles, no cafeine before training (maybe I could chew some coffee beans?)

SiS caffeine+ gels (Berry flavor) work well for me if I need a pre-workout jolt. 75mg caffeine and quickly absorbed. Nate likes caffeine pills too.

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Ouch - talking caffeine gels and pills to a coffee lover. You could get stopped at Italian borders for that.

Yes, I really didn’t “blow up”; I’ve done that before…

I did however hop off the bike mid second interval and almost quit. I knew I wouldn’t re visit the ride later today, so I jumped back on with a 3% drop and finished. It is amazing what 10 seconds off the bike can do for the legs.

Thanks for the response and encouragement! Days like these it really helps.


So many excellent responses here, the TR guys are teaching us well. My penny’s worth is that firstly you showed real mental strength to get back on and made a sensible call to back it down to 115%. As mentioned, 120% is probably at the upper spectrum for VO2 efforts particularly if you haven’t prepared in advance in terms of rest and the right food - 115% is very respectable and still moving the game forward. So much of this is in the mind and you have shown that have the right tools there to work through the plans to suit your curcumstances, adjust to those and keep moving forward. Guess it’s a great learning for us all!! T


I love coffee, but I don’t want to drink a cup on the bike. YMMV!

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