The air density goes down, so it is 'easier' to go fast. Even if your power is down because of the difference in altitude, you end up going faster.

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Brandon Marsh - Website | @BrandonMarshTX | RokaSports | 1stEndurance | ATC Bikeshop |

I'm just wondering if I'm going to be gasping for air during the run???

Did you put in your sea level power and did BBS reduce it for the higher altitude?

You'll probably be ~8% lower in power. You may be faster on the bike because of lower air resistance, but that won't help you on the run.

Not so much on the run, where you'll feel the worse is on the swim.

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How much time should I add into the swim and run from the altitude?

There's no real formula. Some athletes get up to altitude and see no real effects the first few days. Our experience is at 7,000 feet which is 'worse' that Boulder.

Breathe more often on the swim, start out more conservative. The run, we're all running pretty 'slow' anyway, so you might not have to adjust your pacing that much.

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Brandon Marsh - Website | @BrandonMarshTX | RokaSports | 1stEndurance | ATC Bikeshop |

I'm not doing that race, but if you've been training in high humidity (dewpoint over 70F), you it be comparable to altitude? Just curious.

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No. I live in Denver and regularly train the IM course and up in the hills. People who come from any place lower than say, 3000 feet are at a distinct disadvantage unless they acclimate for about a week. The acclimation period for a trained triathlete is a lot shorter than Joe Blow because his/her cardiovascular system is already oxygen efficient. The altitude likely won't be the top challenge for a low altitude rider. The problem (IMHO) is the oppressive heat (heat without humidity but the sun is more intense) and the eastern winds that happen on the plains. There is the very real possibility of a consistent 5-10 knot headwind on the eastern side (east side of i-25) of the course which will be hot and energy draining. If it is cool, cloudy, and still, you will fly.

Altitude vs. heat/humidity?

I think that there was a study that showed some similar performance 'gains' when racing in more ideal conditions. In other words, when altitude trained athletes went to ideal conditions they performed better. And, when heat/humidity trained athletes went to ideal conditions they performed better.

For me, I'm training in oppressive Austin, TX right now. My paces on the run are similar to those when we were at 7,000ft altitude. Both of those paces are slower than when we were dealing with weather that was 'nicer'. 70 degrees with lower humidity.

But, everyone is different. A lot of studies, etc. are based on averages especially for altitude info. Some people's physiology responds well to altitude, others simply don't. Unless you track blood markers, it is difficult to say whether or not you do. Placebo may actually have an effect as well.

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Brandon Marsh - Website | @BrandonMarshTX | RokaSports | 1stEndurance | ATC Bikeshop |

If you are coming from lower elevations take heed of both the altitude and the low humidity. When I first moved here (Denver) from the east coast I could not believe how breathless I was when swimming and how much higher my HR was at any given pace on the run. I don't remember noticing it quite as much on the bike but I wasn't training for IM distances back then.

The low humidity is the real kicker though. I was used to relying on my sweating to gauge how much fluid to take in. when I first got here it seemed as though I was hardly sweating but in reality it was just all evaporating so quickly that I never got wet. As a result I would rapidly fall behind and get very dehydrated very early.

The good part about the low humidity is that of course it doesn't feel as hot at the same temperature, the bad part is that you dry out so much more quickly.

Lastly, don't forget the SPF 1,000,000 sun screen. The altitude makes you burn much faster.

Have fun, it's a great and fast course.

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Jeffrey Sankoff, MD
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It is a sample size of n=1, but my FTP is about 8% higher at sea-level compared to 5,000 ft. I also notice that you can recover from anaerobic efforts much easier. We used to have a crit series in Copper Mountain at ~8,500 ft. You really paid for attacking too hard!

My plan is to rip a PR on the bike leg and call that my adjustment.

I raced IM Tahoe last yr, which is ~6,200 feet. I got there about a week before the race, i live at 500'. I felt out of breath ALL week while running or even climbing stairs.

I had also raced IMMT 5-weeks prior.

Swim: 1:05 at IMMT vs 1:09 at Tahoe

I didnt feel much difference swimming at that altitude while going easy-tempo, i attribute most of the ~+4 min to just starting out way easier at Tahoe and it being very cold.

Start easy!

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Do you train with heart rate at all? If I was coaching an athlete preparing to race at altitude, I'd have them dust the HRM off.

Rather than trying to figure out some formula for racing at altitude, I'd use HR along with your power meter and gps. As an example, 150 bpm is 150 bpm of stress on the body. Don't expect to be able to sit on 160 bpm just because you're at altitude...you'll need to back off.

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Mat Steinmetz

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http://www.ddst.org/...e/Times/altitude.pdf

FWIW I did two 40 minute runs last August running as far as I could in that time. One in Houston the day before heading to Boulder, the second the day after arriving in Boulder. The two runs were within 10 meters of each other on a Garmin 310XT. Different mechanisms. but both limit O2 delivery to working muscles. Obviously, my n=1 may only apply to some. A month later I had my best IM run in Tahoe. Boulder won't be as cool as Tahoe though.

I live at sea level and raced at Tahoe last year.

I noticed about a 15% reduction in the power I could generate on the bike (IE I was aiming for X, but only generated .85X even though my perceived effort was about X). It was hard to gauge the actual reduction in time that cause though since the bike course itself was ridiculously difficult and in no way resembles the Boulder course.

I had no trouble swimming, though, and my time was right where I would have expected a sea level race.

My run sucked, but I didn't notice any particular altitude-related reduction. I am sure it was there, but I was so beat up from the bike course that I don't think I could pinpoint any particular symptom of my bad run and say "yes this is altitude-related"

One caveat though is that despite living at sea level, I regularly travel to Colorado to ski so I am at least mentally used to being at 10kft. I know your body doesn't adapt that fast, and any adaptation you do get you will lose pretty fast, but mentally I was prepared for the difference so maybe that helped at least when running.

This man speaks the truth.

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All of the athletes coming from lower elevations are hosed, and might as well not come so the rest of us can grab some Kona slots....

The bike course has about 4,000 feet of gain. Doesn't seem like much, but portions of that gain are on the Eastern side of the course, where there are some long-ish hills. The wind, if it's up, could be a factor out there. Then, coming back west towards Boulder again you get some false flats and more long-ish hills, punctuated by the "Three Bitches" (Three Marias) very late in the course. You can also get westerly headwinds, which could make the return stretch back to Boulder draining. And then, if it's in the mid to upper 90's like it has been recently, it will be like a blast furnace out there.

Many people comment that one place they feel the altitude on the run is going up any sort of hill. The run course does have some elevation gain if you look at the profile. If you're talking mid to upper 90's and going up a hill, you're going to feel it coming from a significantly lower altitude, I would bet.

I'm going to throw this out there because I need to make a decision soon (I have a chance to race via foundation spot but my link expires in a few days).
Wt: 180lbs
Ht: 6'2"
FTP: 290
Open Marathon Time: 2:57
TT 400 yard swim: 00:05:45
Averages (last 12 weeks):
Swim: 11000yards/wk (3.25hrs)
Bike: 289 miles/wk (14.5hrs) with 12000 ft elevation gain/wk
Run: 50 miles/wk (6.75 hrs)
CTL: 130

What kind of time am I looking at IM Boulder?

Different adaptation at work - just come from sea level to moderate altitude (5000ft) and run up a flight of stairs, and you'll quickly feel the difference. Humidity doesn't increase your hemacrit.

I train at 30ft above sea level and did Mt Mitchell that is at 6683ft, 100mi ride that includes climbing for about 3+ hours straight.

I felt no different.

It seems like what you are asking and what you are really asking are two different things.

You are asking if the altitude will be a problem for you. The answer is maybe.

What you seem to be really asking is will you qualify for kona. The answer is maybe.

We had this debate pretty consistently for a year prior to Tahoe and at the predicted altitude induced apocalypse ended up being overstated. It had an effect but magically the fit people were still fit and the prepared people still prepared.

The real question is what do you want out of this race? Do you want to race to the best of your abilities? Sweet, go do that.

Are you looking for ST to validate that this race will be a guaranteed KQ? Your odds might be better served by not picking a race in the backyard of a city known for producing some of the best endurance athletes in the country. Most races will have plenty of out of towners who are all in the same boat as far as unfamiliar environmental factors are concerned, but I'm going to go out on a limb and guess a few locals are going to show up to this one, and the altitude isn't going to be a surprise to them.