My A race this year is an iron distance event at 5,000 ft - max elevation around 6,000.
I haven't done too much work at altitude. Should I expect a significant loss in performance due to poor acclimatization?
Anything I can do in my training to alleviate issues that might come up with the altitude?
The answer to your main question, loss in performance, is yes.
I did three halves and a full in 2013. My second half was in Boulder, CO, at 6,000 plus feet. Took me 24 minutes longer than my other halves at lower altitudes, or 8% slower. I primarily felt it in the swim, (took longer to get second wind and settle down), and the run. To be honest I really did not notice it in the bike.
A full is an entirely different animal. So for me, would expect even greater loss in performance percent wise. I am a religious zone trainer, using a heart rate monitor in all training and races. What I noticed in analyzing the data after my races is my pace and heart rate did not suffer too much generally (I spend my races in zone 2 - 3) but the altitude seemed to effect me most in places like transitions, hills and longer times getting my heart rate down when I bumped up in to zone 4. Those points cost me time, primarily in the run. My age grouper feeling is that if your cardio is strong, demanded by a full, but you race at 60 to 80% of max, your cardio can handle it. So much so that I may be returning in August for Ironman's first full in Boulder.
I did not do anything special to train other than turn my Boulder trip into a holiday with the wife and go out five days early to try to acclimate. But I have read that is about the worst amount of time to spend at altitude before a race. Consensus seems to be go to altitude the day before the race, or two plus weeks before. There are products on the market like altitude tents you can sleep in, simulating being at altitude. That idea did not excite me for several reasons.
Thanks for the thoughtful response. You raise some great points and solid advice.
I've been thinking of using a heart rate monitor for some time now. Perhaps this is a good time get serious and implement the HR monitor into my training.
The Ironman Boulder is actually the race I'm training for.
Hope to see you out there!
Heyo. I did IM Lake Tahoe in 2013, which is another thousand feet higher in altitude that Boulder. It was challenging for a number of reasons, but to be honest I wouldn't even put the altitude in the top three.* I had no previous performance to compare it to, but I didn't feel like the altitude affected me much at all. (Some of us are lucky that way!) As far as advice: I spent a couple of weekends training at or near altitde in the months leading up to the race and I tried to be conscientious about not overexerting myself. Those worked for me, and I walked away afterward feeling pretty great.
*Those would be (1) the amount of steep climbing (on a bike course we weren't fully allowed to preview until the day before race day), (2) the unexpectedly cold temperatures (which persisted all day), and (3) the lake mist which made sighting nearly impossible for a while.