For short repeated efforts you will probably need to go harder than 5 min max to get your hr up to the target being discussed.
You should try following session: 4 blocks of each 12 minutes with 2 minutes rest. Each block consists of 40sec on and 20 sec off (50% FTP).
I did them on with 370 watt give or take, with an FTP of 310 and 5’ max of 400. I can assure they were at VO2max 
Well if there are any absolutes for this kind of training, there are no absolutes…
Although 4 x 12 minute blocks is 48 repeats with scant 2 minute recoveries between blocks, which is what was mentioned by @Captain_Doughnutman as a requisite due to the HR lag. ~32 minutes at target power is almost double what is done in something like Kaiser
Hard, really hard.
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Or either of these two workouts (which are the same, just arranged differently):
Come on, what are you scared of? They have a 1:5 work:rest ratio…it’ll be easy! 
This didn’t come from my mouth. 
Even 30-second efforts get really, really uncomfortable, eventually outright brutal, especially with short, short, shorter recoveries between repeats. But with equal rest, you can do a relatively enormous amount of them when compared to recovery-matched 3-minute efforts.
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@chad I find the newer 30/30 style VO2 work to be brutal compared to the older 1.5 min or 3 min intervals. Is there a limiter that would be contributing to that?
Funny thing, @ErickVH, is that I mentioned VO2 kinetics on our most recent podcast and it got me thinking about this very thing.
My thought process so far is something along the lines that if your kinetics are slow, you could get farther into the longer intervals on anaerobic reserves and then eventually fire on the aerobic cylinders, but could this result in a heavily anaerobic set of 30/30’s if a slower VO2 response means you’re never really revving the aerobic system due to the short intervals.
I’ve read often that it takes about 90 second before the aerobic system is fully contributing, but I’m still working through this and coming up with as many questions as answers.
Perhaps @gdumanoir with his background in “microvascular PO2’s” could shed some light on the matter…?
This really describes Bluebell vs. Kaiser for me and touches on the root of my question: does a proper/optimal Vo2 effort require heavy or very heavy breathing?
Thanks @chad and @ErickVH for pulling me in.
There are a couple of things to think about here. I’ll start with some of the kinetics ideas first and then I’ll move into some of the microvascular/cellular mechanisms.
When there is a transition to a new workload (rest to exercise, recovery interval to work interval, work interval to higher work interval), aerobic energy production (measured at the mouth as oxygen uptake, measured at the muscle as oxygen consumption) increases in an exponential manner. I won’t put the equation here, but the key variable is something called the tau. Tau is the time that it takes to achieve 63% of the steady state response (steady state is important here). Therefore to reach a complete steady state it takes approximately 4 tau’s. In a healthy, young individual tau is around 20-30 seconds, so to achieve a steady state requires approximately 2 minutes. The fastest tau I’ve heard of is Paula Radcliffe’s (women’s marathon world record holder) 9 s tau! The kinetic response is determined by an integration of O2 delivery mechanisms (think cardiac output, hemoglobin content/concentration, partial pressure of O2, etc.) and oxygen utilization (think enzyme activation within the mitochondria) and more specifically, how fast they respond to the new ATP demand of an increased exercise intensity.
So, when we transition to a new work rate/exercise intensity we have this “delay” in aerobic energy production. However, we still need the ATP to meet the demands of contraction, so we must supply this via anaerobic means (phosphagen system and anaerobic glycolysis). The drawback to this is that we have a limited supply of high-energy phosphates (think PCr) and anaerobic glycolysis results in fatiguing by-products (exact mechanisms of fatigue is still debated, but I think we can say changes in pH play a role). So, individuals with slow kinetics would rely on ‘more’ anaerobic energy production and the experience the resulting fatiguing mechanisms. If you make multiple transitions during a training session or throughout the day, slow kinetics results in “accumulated fatigue”.
The issue here, with VO2max intervals, is that the intensity is in the very heavy and/or severe domains. If you do exercise in the moderate or heavy domains, you will achieve a VO2 steady state and energy can be supplied by aerobic means and the kinetic response is a key determinant of that steady state performance or transitions within that performance. When we work in the very heavy or severe domains, we don’t achieve a steady state. This isn’t to say that kinetics are no longer important, but we must be aware that a significant component of energy supply is now anaerobic in nature. We are now also dealing with your W’ or anaerobic work capacity… will leave this alone for now.
So, to answer the question about 30/30 vs. 3 min/3min we have to think about both the aerobic contributions and the anaerobic contributions. In both cases the exercise intensity is such that aerobic energy supply cannot meet the energy demands (both from a kinetics response and an absolute energy demand). Remember, above threshold (CP, LT, FTP whatever term we’re using today) work requires anaerobic supply and I won’t reach a steady state oxygen uptake/consumption. So, in a 30 s interval, there is insufficient time to achieve the aerobic steady state and the intensity is too high for aerobic energy supply only. In the 3 min interval, I can achieve an aerobic steady state, but the intensity is too high for aerobic energy supply only, so not really a steady state.
The key to interval work is that VO2 kinetics follow the same response and tau during recovery phases as well. So if you have fast on-kinetics you have fast off-kinetics (essentially you recover faster in between efforts). However, the oxygen uptake stays elevated during recovery and maintains a high energy flux and is the stimulus for adaptation.
There are a few things at the microvascular level that might contribute: we don’t store oxygen very well, so we rely on its transport from mouth to muscle to mitochondria to fuel metabolism. If there is a bottleneck in any of the O2 delivery processes this will impact one’s kinetics. However, during interval work there is a ‘priming’ effect from the previous interval such that blood flow and O2 is present. We also do a really good job of extracting O2 from the blood. Indeed, any kinetic response of deoxygenated hemoglobin (HHb) is very fast (much faster than the oxygen uptake response). So, it looks like O2 delivery does not ‘limit’ in healthy individuals (but does in older and clinical populations and maybe unfit individuals). Thus it appears that there might be an enzyme activation issue, but again, ‘priming’ exercise elevates enzyme activity.
So, why do 30/30 feel harder? I think it’s due to lack of time for off-kinetics rather than the on-kinetics. The idea behind intervals is to keep the aerobic system elevated for the entire session (Chad did a great job of describing this on the podcast) with periods of recovery. I think this recovery is key for the sensation of fatigue (along with fatigue processes) and 30 s doesn’t allow for you to ‘feel’ rested/recovered whereas 3 min allows for more recovery (whether physiological or psychological).
Ok, probably leads to more questions than answers, but my goal is to press Chad, @Jonathan and @Nate_Pearson to hold a ‘physiology of cycling’ in-person event at TR headquarters over a weekend. Physiology talk, riding, beer drinking… what could be better! It’ll definitely “make you faster” (key phrase to encourage Nate)
Happy to chime in a bit more if there are more questions
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So I may just have a long ‘tau’ and the longer sets in the 30/30 model is just hammering my anaerobic system while it ramps up to steady state? Will this improve with conditioning? Is there any benefit to having a longer tau?
You may have a long tau, but in either case there is such a big contribution from anaerobic energy supply that it will ‘always’ contribute to this type of training. You’ll get used to it and, to be honest, I prefer the 30/30 now. I find it quite sustainable. I know the 3 min at maximal aerobic power is going to hurt for longer - I like the short, intense efforts now that I’m used to them.
Yes, this will improve physiologically with training - improved O2 delivery (increased cardiac output, better matching of blood flow to working muscles, increased capillarization) and improved O2 utilization (increased enzymes, glycogen storage, fat metabolism) all help to improve VO2max and performance.
However, “it never gets easier, it only gets faster” applies as every time you reassess, the intensities bump up a bit and the sensations are similar! (Un)fortunately, @chad is good at this part of the training process. [a little shout out to Chad for doing such a good job adhering to the principles of training throughout the plans]
There is no benefit to having a longer tau. Where kinetics really come into play is during aerobic steady state transitions - think gran fondo, road race, crit (to a degree), TT (to a degree) where you are working below threshold, but have to make transitions to higher PO’s (an attack, a hill, etc.). If you have a fast tau, you get to the new sub maximal steady state faster and supply energy via aerobic means (theoretically infinite and non-fatigueing) vs. relying on more anaerobic energy supply (and potential fatigue) while the slow aerobic system meets the demand. If you have fast kinetics you achieve the steady state faster and don’t rely on anaerobic metabolism.
Remember too, that during a race, you have limited anaerobic energy supply (this is the W’ or AWC). Once you use it up, you have no more to draw upon and have to work below threshold (go slow when others attack). If you have slow kinetics you use the W’ faster and won’t be there when the important attacks occur.
This paper might help a bit with some of the physiology, rationale and modelling of performance. David and Phil do a great job explaining things and Phil was a member of the Nike Breaking2 Performance team:
Cheers
Greg
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No comments (cuz now I have a lot of new reading to do!), just gonna put up some more weeds…
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Oxygen delivery lags behind the oxygen consumption and this creates an oxygen debt…oxygen debt does not cause a drop in the oxygen saturation of our blood (hypoxia), but rather forces our body to produce energy anaerobically (literally without oxygen). The imbalance caused by the oxygen debt and the anaerobic energy production can actually last for protracted time and results in excessive glycogen consumption causing problems, even on longer races such as marathons if you go out too fast. Improved fitness from training will reduce the time it takes for the body to ramp up O2 delivery.
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Performance of prior moderate exercise resulted in faster VO2 pulmonary kinetics and also improved exercise time at 100% of VO2max. Prior heavy exercise, although effective in accelerating VO2 kinetics in a subsequent exhaustive exercise, it resulted in a shorter exercise time at VO2max compared to no prior exercise and prior moderate exercise. These results may have important implications for the preparation of athletes in training and competition suggesting the use of an optimal warm-up exercise intensity (and duration) with optimal recovery combination to improve performance.
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So tau is highly trainable. Good to know.
Yes, but it’s not something to ‘target’. Just do good training and it will take care of itself.
The reason I say this is that modelling your kinetics is time intensive (multiple exercise transitions with gas exchange data and specific software to analyze)
Just “enjoy” the efforts!
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I nominate @gdumanoir as Grand Poobah of the VO2max High Council.
Anyone who can anticipate my questions and answer before I ask deserves to be my leader!
(Full Disclosure: G is a fellow Canuck – country and province! – so I’m a bit biased in my nomination.)
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Except my VO2max is famously low!
When I was in grad school, my supervisor told all the students in his exercise physiology lecture to ask me about my ‘impressive’ VO2max. I had to tell them it was ‘impressively’ low. To be fair I was an Olympic weightlifter at the time and was able to produce about 1200W on a 30s Wingate test (5s peak power), so my specific training saved me later in the year…
I’ll take the hat though!
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I may have this completely wrong, but would a lot of long, slow hours (e.g. Tradition Base) induce the mitochondria adaptations which would effect those enzyme activations? In other words, will having a strong, deep base ultimately effect the speed of your kinetic response?
(as a side note, I’ve read (only in a single source) that VO2max could be trained via only time in Z1/2 to the same level as training via time in Z5, but it would take literally years upon years, and physiologically you’d start to lose VO2 capacity (from age) before “full” training effects ever got a chance to take place.)
Quick response - New Year’s Festivities are about to commence…
Long hours of Z1 are very good for improving efficiency (a key performance determinant) and also have some cardiac and vascular adaptive inputs. But, you are correct that they take a significantly larger amount of time investment. Not sure about the aging piece ‘over-riding’ the fitness piece - if it did I’d say you had a poor training plan.
HIIT training has a profound adaptive response, but is unsustainable if over utilized… fatigue is too great.
Both high-intensity and long-duration training activate PGC-1alpha, but through different mechanisms (AMPK for HIIT, CaMK for long duration) with similar outcomes physiologically. This is why mixed, appropriately prescribed (intensity and duration) is key for positive adaptations.
I’ll plug Paul Laursen and Martin Buchheit’s new book and course www.hiitscience.com as a great resource for all of this. I haven’t received a copy of the book yet, but have seen Paul (another Canadian, now living in Revelstoke) present on a bunch of these concepts and base a lot of my teaching on their HIIT papers. Paul has another review article on high-intensity vs. high-volume training that is excellent as well.
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I can’t thank Prof. Dumanoir enough for his elaborate and thorough response on a topic that I love to grapple with endlessly. This only reminds me to pick his brain more often. Thanks so much Greg!
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