Hard Intervals @ Altitude
With IMs in Boulder and Tahoe, more people are starting to do some training at altitude in preparation. I spend 2-4 weeks twice a year @ altitude during the IM prep phase, basically from RR #1 to RR# 2. I'm constantly learning stuff about how best to train at altitude. I'd like to raise one specific issue: how to handle FTP and TP intervals. Research (and my experience) shows that athletes can maintain their sea level speed/power for short intervals, up to somewhere between 2 and 5 minutes, depending on how well trained they are. After five minutes, the power and pace one can hold for any given interval will start to deteriorate.
As I look to doing FTP bike intervals and TP run intervals, I know that I will go slower for the mile repeats in the plan, or do FTP intervals at a lower wattage (FTP drops about 7-10% when tested @ 2500 meters, about where I am now). So, I'm asking myself, particularly for run intervals: Should I accept the slower speeds and do the mile repeats, or should I try to do intervals of a length which allows me to run at the same pace as I would at speed level. For mile repeats, that would be in the range of 0.65-0.8 miles, I've found.
Which makes the most sense, at least in terms of prepping for an Ironman, run those intervals more slowly, or make them shorter while keeping the total work time the same, e.g., a TP of 7:17 for 2x1mi means a total work time of 14:30. My instinct tells me to run the shorter distance at the same speed, so I get the same stride length and neuromuscular effects as I would at sea level.
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Seriously, though ... my response doesn't reflect any learned scholarship of altitude training or race preparation as much as my own reasoning. In my simplified view, I see training (until there are the physiological adaptations) at altitude kind of like doing so with impaired or diminished capacity. So the original capacity - the sea-level fitness you have - is the game you brought. If you showed up at altitude with, say, fitness level 8, and then at altitude you're 8 minus 2, or whatever. What's key is making sure that you have the highest level of basic fitness. To maintain or improve that fitness, doing quality sessions to the highest level of quality (so, longer instead of shorter intervals, sorter recovery, or at the proper instead of a diminished pace) are going to contribute more to overall basic fitness and then you take that on up the mountain and use it at altitude for the type of racing you're doing. I see this is bringing the 9 back up the mountain, so you're up there now at a 9 minus 2. Instead of the lesser gains made doing slightly less hard work at altitude.
That's the other thing: specificity of effort. Again, were it me, I would be doing aerobic IM-paced efforts at altitude as if executing race day. Maybe not by pace/watts, but definitely by HR. And let the adaptations over the time I had.
Again, all this is my own reasoning (it's actually what I have been thinking about for heat acclimatization if I do Lou this year). Dunno if it would completely apply to altitude adaptations, but I suspect that it would.
I train @ altitude primarily because I have a home @ 8400', thanks to my parents, who retired here in 1969, in a very beautiful part of the country with extraordinary cultural and recreational offerings - Aspen/Snowmass. Even if there were no value to living @ altitude -there certainly is, but that's another topic - I would still be here, and have to deal with how to manage what in essence are two different FTPs and VDOTs.
So I spend a lot of time thinking about altitude and endurance training/racing. I have not found any research specific to this question, so I thought I'd see if anybody had some ideas about how to think about it. After two weeks here, with 2+ to go, trying to do standard EN IM prep phase workouts weeks 14-18, I've come to the following (current) conclusions:
In no way am I saying this is scientifically even logically justified. It's simply what I've landed on after doing this for 10 years now, 4 or more weeks a year.
Oh, an addendum, The reason the biking is different than the running. I think the concept of W', or "Work Above Threshold" applies here. Background article. VERY simply, the idea is any time a cyclist goes over FTP in a workout or race - IOW in a situation where he is never stopping completely to have coffee, sleep at the side of the road, whatever - he starts using up what can be thought of as a fixed supply or reserve of supra-threshold work available. "Matches", is the vernacular. And the amount, or time available for work above threshold is a hyperbolic curve - the higher you go go above FTP, the faster you use up that reserve. (Exponential equation?)
So … doing shorter bike intervals @ my sea level FTP would probably result in me not completing all of the total work time in the plan. The difference between biking and running? We are asked to do 40-55 minutes of work @ FTP in a session, while we only do 15-20 minutes @ TP in run workouts. 15 minutes @ a 5 K pace is doable; 45-55 minutes @ 110% of FTP is not.
Good discussion and I see valid arguments from both you and Dave. And this is totally intuitive, for sure. My notes:
As we all know, the rub about training and living at altitude is that decreased O2 = decreased watts and paces = your body becomes less able to hold sea level watts / pace (detraining) until your body adapt by growing more red blood cells, blah, blah. So shortening the work interval so you can (1) hold the prescribed watts and (2) get in the assigned cummulative work interval load should (intuitively) help retain your ability to hold those higher watts (?)
Good summary by Rich and Al mirrors my experience of training 365 @ 7000'. Its where I live, and I don't usually have time to drop down to sedona or phoenix to do interval workouts, which would be ideal. Live high, train low. So I build speed slowly, but I do build speed/power.
Bike: I find 2x20' FTP is hard to accomplish @ 100%, so I have to typical mods which either shorten the intervals and add rest or ease up on intensity:
shorter intervals for same total: 4x10' @ 100-105% or 20' @ 95-100% & 2x10' @ 100-105%
same intervals 2x20' at reduced rate: 90-95%.
Run: Check out Jack Daniels official VDOT calc: http://www.runsmartproject.com/calculator/ This has compensation for altitude, wind, temp. My 3+ years of EN training cross checks very well with his calc (which I know he has calibrated here in flagstaff with his local proteges) I've found that TP mile pace is 20" slower @ 7000' than low-alt (0-2500') and accordingly my VDOT is actually ~2 higher than my 5k tests @ 7000' would tell me. The calc says the same. I don't typically have problems running Z4 mile repeats at the higher VDOT pacing because its only 6ish minutes, I may need an additional 30"-60" rest. But I do have problems pacing 5k at the higher VDOT. Example: I'm training at 54 vdot now (last 5k time is equiv to 52 vdot), so @ home I do z4 @ 6:30ish. Last week I was down in Tucson and did 4x1mile @ 6:00 comfortably and my easy recovery pace/hr was ~30 sec faster than usual. I am however probably due for bump in VDOT. So I test @ 52, train @ 54, but @ sea-level may be @ ~55-56.
Swim: breathing is harder, and even breathing 3 strokes leads me to deficit pretty quickly. Other than that I still do all my threshold work as 'normal' breathing on 2. Swimming is just easier on the body than the same threshold work in running/cycling.
Rest: recovery and rest becomes much more critical at altitude when doing threshold work, I find I have to periodize my weeks, focusing on 1-2 hard work weeks, and then standing down (by eliminating low priority stuff, scaling back speed work, etc) for at least a week.