Interval Training At Altitude

I train at altitude primarily because I have a home at 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 performance value to living at 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 standards for how to judge my swim, bike, and run performance.

So I spend a lot of time thinking about altitude and endurance training and racing. I have not found any research specific to this question, so I thought I’d brainstorm some ideas about how to think about it. After two weeks here, with 2+ to go, trying to do standard Endurance Nation Ironman prep phase workouts for weeks 14-18, I’ve come to the following (current) conclusions:

1. Runs. I do long runs “low”, at an altitude of 6500′, where there is a good high school soft surface track. I do the same total work time prescribed in the plan, and shorten the intervals, doing them at the same pace I would at at sea level. My thinking is, at this stage I’m not really training to get faster, but to maintain things like cadence, stride length, general efficiency of neuromuscular firing and form which come with faster paces. Going for 3-4 minutes instead of 7 minutes at a stretch allows me to do that. If I went a full mile instead of the halts I’m doing, I’d go slower, shorter strides, probably slower cadence, etc.
2. Bike. A different story, in my opinion. There is no place truly flat to ride; there is an endless variety of hills to go up and down. All different gradients, lengths and elevations and all of them spectacularly beautiful. So what I have done is “altitude adjust” my functional threshold (FTP), dropping it by 7-10%, depending on the elevation I’m at between 6000 and 10000′. Above 10,000, it’s simply survival, no opportunity for doing hard work. Today, for example, I did my FTP intervals on a 7.5 mile route rising 1300′, between 3-7%. mostly in the aerobars. They were at 85% of my sea level FTP, about 94% of my altitude adjusted. FTP. So my basic strategy is to get in a similar feeding of work effort (RPE), of similar time, for any cycling intervals I do, but at a lower power output.
3. Swim. I do the workouts as written. It’s all by RPE. Short efforts, 50 yards, I do at the same speed as sea level, and it drops off from there. For 400s, say, I would go 6:40-50 at sea level, while I do 7-7:15 here.

Why is the biking is different than the running? I think the concept of W’ (“W Prime”), 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 – in other words, 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”, I think, 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.

So … doing shorter bike intervals at 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 at FTP in a session, while we only do 15-20 minutes at TP in run workouts. 15 minutes at a 5K pace is doable; 45-55 minutes at 110% of FTP is not.

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.