Optimum duration for VO2 intervals
I know the guidance for OS VO2 work is to use whatever intrvals you can to maintain power across the total duration of the set but wouldn't something in the 4-5min range be preferred to 1 or 2min intervals? With the shorter intervals a larger proportion of each may be accounted for by anaerobic work. If we assume the first 30sec has a large anaerobic component then we can minimize that total contribution by only doing 3-4 intervals of longer duration although that may require slightly lower targets within the VO2 range - typically considered to be 105-120% FTP.
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Well, the VO2 intervals are hard, and it takes time to build up from 30/30 to longer intervals. 4-5 min intervals are kind of extreme in my opinion, and I settle for around 2.5 min. I prefer longer intervals over 30/30s for two reasons:
I think the VO2 intervals on the bike are equivilent to 400-800s running or 1-200s swimming. It's hard to imagine doing 400s (swim) or miles (running) at that "VO2Max" effort level. The desired energy systems are not going to be worked using those longer (> 3 minutes) intervals, IMO. You'll be backing off (unconsciously) trying to make sure you can finish the whole set.
Hey Joel,
i digged around the same question.
Last year was my first season and outside of EN, I did the VO2 work is 3-5min intervals on the bike, the guidance was for power and HR, but I had only HR and I was training for Olympic/Sprint.
Inside EN i learned that the 120% take priority, and the lenght is flexible between 1'-2.5' (equal recovery time). This this thread.
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I did 4wk OS VO2 block as per plan first, did had good but not so great results.
And then ... i digged out a study how to optimize VO2 training. This thread.
I learned 3min sounds a good estimate, most study showed most hold their VO2 power for max 5-6min, hence 60% is 3-4 min.
I learned that I need to plan for more recovery, after every 2nd interval.
I am actually building up more VO2 work on the Sunday and go beyond the EN OS inter. plan,
1. 12' ON week 3(3'), 3(3'), 2'(3'), 2'(3'), 1'(3'), 1(3')
2. 13' ON week 3(3'), 3(3'), 3'(4'), 2'(4'), 2'(4')
3. 15' ON week 3(3'), 3(3'), 3'(4'), 3'(5'), 1'(3'), 1(3')
4. 17' ON week 3(3'), 3(3'), 3'(4'), 3'(5'), 3'(6'), 1.5(3'), 1.5'(3')
5. 18' ON week 3(3'), 3(3'), 3'(4'), 3'(5'), 3'(6'), 3'(6')
First I make sure that I am always hit the 120% - so far that worked for me fine (I am in Week 4 this week), than I build up one 3' intervals each week and I extend the recovery time. I do active recovery - means I control my efforts in the recovery interval but maintain 50% a FTP level and make sure if my HR goes back into Z1, if not drop to 40% FTP and recover longer.
Why i am doing this? well...
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1.) I do not have IM on my schedule, so I have not much volume to add into my training sofar, I have 1-2 road races and 1 short TRI and 1 (hilly) HIM. So VO2 works helps me getting stronger on both ends.
2.) Like to push myself(mind) beyond my (envisioned) limits (actually 50min Z3 after this feels like nothing
I do the same for the FTP work where I extend the 10-15' intervals to 20-25' intervals, but keep the overall time inline with OS plan.
3.) Even i am only in the middle of this plan, I feel that this is not bumping in my Tuesday bike, and I feel I make progress each week on my FTP work.
This reference from Peaks Coaching group suggests VO2 max intervals be between 3 and 10min depending on where within the range your are working. The article talks in terms of % VO2max power as opposed to % FTP but we can assume that 90-105% pVO2 is roughly equivalent to 106-120% FTP (although it isn't necessarily a direct relationship).
Using Intervals to Target VO2max Adaptations
The top end of the VO2 range is 120%FTP. I'm not suggesting trying to ride 5min intervals at 120% but 110-115% should be realistric for 4-5min intervals and that falls directly in the middle of the VO2 range based on Coggan's guidance. Coggan also suggests VO2 intervals should be in the 3-8min range.
So if you are strictly targeting 120% FTP then I guess 2-3min might be appropriate but I'd still think that we can reduce the contribution of AWC by doing fewer longer intervals even if that means coming down off the 120% top end and settling into the middle of the VO2 L5 training range. Granted, we're talking about a continium here but the closer you are to the break points between the zones the more likely you are to be splitting the focus of the effort, not that that is necessarily a bad thing all the time. But if you can only maintain 2-3min intervals max at a give power level chances are you are working more towards anaerobic capacity and you have a bit of a disconnect between FTP and pVO2max.
I guess this is another case of the EN approach being to work minimally for the desired intent. I had a similar thread about 1-1.5 mile running intervals @ Z4 when something closer to Z5 might actually be more appropriate from a strict physiological perspective. I'm more looking for discussion and debate than an answer here.
Bottom line - hard work is hard.
I did some of these longer VO2 intervals in a VO2 clinic a couple of years ago, and along with the high intensity running work, just absolutely fried myself. I watched my ability to hit VO2 and FTP benchmarks plummet over 6 weeks, and had to pull the plug and go through some extended down-time to get back on the horse.
For athletes who are good at monitoring their own recovery status (I'm not), longer VO2 intervals can certainly have a place in training. Interestingly, Skiba notes that many of his athletes recover better from VO2 work than from FTP work, while around here, the popular notion is the opposite. Not sure why that is.
In this case, I'm not aware of any particular benefit from doing, for example, 4min intervals at 95% VO2 versus 2.5min intervals at 100% VO2 (made up numbers, you get the idea). Either should elicit similar VO2-type adaptations. Now, if you're talking about going from 2.5min at 100% VO2 to 4 min at 100% VO2, then yes, the adaptations should increase, making you faster.
When I used to row, and our sprint races were about 6min in duration, we spent a lot of time working on 90s and 3min intervals, as well as on longer, steady-state work. Seldom did 4.5-6 minute intervals. I think it was related to recovery cost and the overall structure of the week, though it could have been just because that's the way it was always done...
Tonight I switched from 10X1' @ 120% to 6X'2 @ ~118%. Next week I plan to try 4 or 5 X3' @ ~115%.
I did this to confirm that 100%-120% rule applies to my current fitness. I came out with a 1.22 ratio.
I've concluded in my own simplistic way that we are what we train. And also that each of us has a tendency or a talent for fast twitchy sprinter kind of stuff or slow twitchy tempo you to death stuff. How much is nature and how much is nurture? Dunno. But if you believe that if it's hard it's probably good for you, then Joel's 3-5' intervals at 100+ are awesome. I like them and I think it is the hardest work to be found (maybe a tie with 2.5' at 120ish%). But you really have to focus on and set aside time for recovery, which I think the roadies do far better than most triathletes- mostly because they don't run.
Last year I did a lot of short supra max efforts bc I'm lazy and lo and behold, that's where I excelled riding- short punchy efforts. I did less sub max lfr (long fast riding, like abp) and suffered when in road races where I needed that. N=1.
I always think of Cav who gets towed over the mountains but then explodes and can't usually be touched in the field sprints.
Joel, there is one point in this context which got me thinking in here.
"If we assume the first 30sec has a large anaerobic component then we can minimize that total contribution by only doing 3-4 intervals of longer duration".
In my case my HR is about 30secs behind, it is also 30secs or more behind if i recover, hence the total HR effort is roughly similar to the interval ( if 1' and greater), It is just shifted by 30secs.
So the one key to this discussion to be clear what do we want to train primarily with the VO2 sessions.
-> to lift our FTP or -> to increase our cardilogical system.
What I understood in EN we do the VO2 stuff to have a healthy FTP/VO2 ratio, so we can train to raise our FTP and do not plateau.
We do this by holding VO2 wattages in intervals. (my visualization is "I am pressing 120% watts to make my legs to adopt")
Your questions (and the theme of McGregors articel is) about how to develop best VO2 capacity (like roadies do).
1.) I do not know much how is a roadie way of training is useful to non-drafting triathletes. But I know that we do not train like swimmers do for ROI reason.
2.) VO2 capacity is a model which is part of 6 capablities model. In our plans we do not have sessions to develop the other parts in. So we need to discuss those than as well.
That said, I am sure pressing 90-100% pVOMax for a longer periodes will also bring adaptations to the muscles, like riding on 120% FTP 1-3' intervals will increase VO2 capacity over time. At the end both intensities are very close and the uncertainties of both way to estimates the power levels overlap.
So each way will bring simlar benefits but good luck with your training.
I think an important point fromt he McGregor paper is that it can take anywhere from 60-180sec for oxygen uptake to actually reach VO2max. As a result a shorter interval, even though you might be working in the VO2 range, might not elicit VO2max and won't stimulate the adaptations we're trying to target. I'm planning to increase the length of my intervals to ~5min as well as the total volume over the next few weeks while dropping the intensity level down towards 112-15% FTP. Unless we go and get tested for our pVO2max we are really just estimating the appropriate intensity based on % FTP. If I knew my pVO2max I'd set my interval duration and whatever length I could sustain right at the power through the entire session - going over pVO2max doesn't stimulate greater oxygen consumption, the difference just gets accounted for by anaerobic pathways.
1) energy system development - training the systems that supply the energy to the working muscles to be able to supply more of it (making the mitochondria in the muscles better at synthesizing ATP)
2) oxygen/glycogen delivery development - training the systems in the body that supply the ingredients for ATP (mostly oxygen, glycogen) to deliver that more efficiently.
Now, reasonable people can disagree about this, but what I believe is that most of our training should focus on #1, because #2 is a passive by-product. IMO, the goal of training isn't to improve your efficiency of delivering oxygen, or to improve the stroke volume of your heart, or to decrease your heart rate at LT. Those are by-products, or side effects, of placing more demand on those systems to deliver oxygen and glycogen. That demand is placed by the muscles working harder. Therefore, the primary goal of endurance training is to continue to put yourself in situations where you are doing more work, requiring more ATP, and letting the rest take care of itself. The heart and lungs will adapt if the muscles put the load on the system.
So, what's the consequence of this philosophical rant? :-) It has to do with training type.
We can all agree that FTP-style intervals, in theory below LT, improve the muscle's ability to produce ATP without overly calling on anaerobic glycolysis (it's about a 50/50 split between aerobic and anaerobic at LT). This allows for recruitment of some of your fast-twitch muscles, accelerating the conversion of the convertible fibers to more slow-twitch type, and gives your mitochondria a heck of a workout (all good stuff.
Well, what's the goal of VO2 training? I often see comments like "the first 30 seconds, you're not even in VO2 HR, so you need to go longer". Conversely, some mis-interpret how the ATP-CP system works to think that anything in the first 15-30 seconds of exercise is relying on that system (only true if the effort is much closer to maximal). If the goal of VO2 training is to train the supply side (heart/lungs), then you're probably right. If the goal is in training the muscles, then total time in the level would make much more of a difference.
at this link
http://home.trainingpeaks.com/articles/cycling/power-training-levels,-by-andrew-coggan.aspx
There is a summary of the expected training responses to different power levels. Based on this, I'm of the belief that, as Chris said, everybody is right. Some elements of VO2 training seem to be focused on improving the supply side, in which case, longer intervals are probably better. But there are also demand side benefits, where the longer duration may not matter as much.
Long story short, for an athlete who isn't seeing gains with shorter VO2 intervals, longer ones are probably worth trying. Especially dudes like Joel, who are studs to begin with and are looking for any and all possible edges to sharpen.
-keep in ind that VO2max is not JUST the supply or use side, it's both. One or the other is likely the specific limiter of your VO2max at any given time but there isn't a way to determin that without some rather invasive testing - muscle biopsy anyone? So in my mind the delivery ansystem and energy system (actually utilizing the oxygen) need to adapt in tandem unless you have some sort of significant imbalance between your ability to supply oxygen and the muscle's ability to actual use it.
-it's probably best not to bring HR into this discussion because that is a response to the work and not really of interest. Although I realize some only have HR as a training guide. I don't care what my HR is as long as I know I'm working in the appropriate power output range. Again %FTP isn't quite as good as if you knew your pVO2max but it's pretty good and more accessible since you don't need a lab test to determine.
- I appreciate the compliment. I'm very analytic by nature so I'm always thinking in terms of how to get the most out of everything - ROI.
Gents ... thanks very much for sharing your thoughts here.
Joel, yep you are right HR should not be part of the discussion, i misread this.
All said i think to approaches to decide an optimal VO2 interval duration are
Approach 1: 60% of Tmax at 100% P@VO2peak (see ultimate-interval)
Approach 2: 3-10 min at 90-105% P@V02peak. (see McGregor)
Mike I am with you, if one approach does not work, than the other is an alternative.
Despite discussion on the differences, both approaches have on some points in common,
* the intervals are on the longer side than what the EN plan subscribes
* the overall ON time spent in those power zones are longer than in our EN plans
* they base on some testing of the VO2 level
* Recovery is a key element
I set-out 3 weeks ago to play with approach 1, I change the 2x20 FTP test to 5/10/20 test to get a FTP and VO2 Power levels (once I am in Race Prep i go back to 2x20 FTP test), work with 3min intervals (60% of 5min) as much as I can, use a HR recovery protocol between intervals and build up ON times up to 18-21min.
Would be interesting to compare experiences after a couple of weeks .... thanks again
what you're saying is right, but it does ignore the results seen by Billat's team using 30/30 intervals (30s @VO2peak, 30s easy). Also shown to have significant results.
Lots of different ways to skin a cat!
Mike, if you look at the study from Laursen, they had one group doing 12x30sec intervals, but with 4.5min recovery interval, not at 30sec which guess is a key in the intervals from Billot.
BTW: I dripped over this articel http://www.pponline.co.uk/encyc/interval-training-how-to-improve-your-fitness-and-increase-your-vo2max-471, not sure if it adds anything into the discussion, but shows how far back discussion on optimal interval length goes