The Effects of Altitude on Pace - Preparing for Jemez 50k

Jemez 50K is 10 days away. I've read a couple race reports from friends, and I'm not ashamed to clearly say it scares the dickens out of me. Michelle ran a 9:38 at the 50K there last year, and she's a FAST runner. Nick ran the 50M there and warned me it would be the hardest race I've ever done. I've never run at altitude, I've never even vacationed at altitude. I'm nervous.

Now I know so much of race day can skew finish times wildly. Things like:

• Weather conditions
• Altitude sickness - headache, nausea - aside from the general effects of difficulty breathing
• How technical the trail is
• Elevation grades

But I'm a planner, and I wanted to have a general idea of pace in my head before I get there. Can I expect to be running for 8 hours, or 11-12 hours??? That's a wide time range that I wanted to narrow down a little if possible. The biggest question to me is the effects of running at high altitude. Running 31.1 miles doesn't scare me anymore, running up a mountain and back down doesn't scare me, but starting a race 7000 feet above sea level and then climbing to 10,440 feet at the top of Pajarito Mountain - that scares me.

I found a cool running calculator online, but I'm not sure how real the results are. It's located here:
http://www.runworks.com/calculator.html

And they sum up the calculator this way:

"The running calculator uses the distance and finish time of your most recent race to approximate your current level of fitness. Your performance is the result of many factors, including the maximum rate at which your body can process oxygen, your lactate threshold, and the mechanical efficiency of your stride. The calculator lumps the effects of all these factors into a single variable called VDOT, using a method popularized by sports scientist Jack Daniels in his book Daniels' Running Formula. 

A given VDOT value corresponds to successively slower average paces for longer distance races. For example, a 24:00 5K race time (7:44/mile pace) represents the same VDOT value and overall level of fitness as a 49:47 10K race (8:01/mile pace). Once your current VDOT has been determined, it can be used to predict your race times at other distances. The closer the other distance is to the original race's distance, the more accurate the prediction will be. Due to differences in physiology and training, some people may be better at longer distance races than shorter ones or vice-versa, but the calculator should yield accurate results for most runners. 

The recommended training paces are also determined from your current VDOT value. They correspond to the five primary training types as defined by Daniels: everyday easy runs, marathon pace runs, tempo (lactate threshold) runs, intervals, and repetitions. These training types and the purposes served by each are explained fully in Daniels' book.

The data for pace/time adjustments related to elevation, temperature, and wind speed are adapted from Daniels' chapter Utilizing Your Training Environment, in the 1st edition of his book. See the text for more information."

Very, very cool. You can alter by elevation, by altitude, and like the McMillan calculator, gives you suggested finish times for other distances than the one you enter.

Jemez is 7000ft elevation gain. Gorge Waterfalls 50K back in March was 6500ft elevation gain with some similar grades, so I put that in because that race was at sea level. So it mostly varies the altitude without having to consider a difference in elevation changes.

So I entered the 8:30 finish time from Gorge Waterfalls and clicked the altitude adjustment, and here's what they came back with:

Elevation	Time	min/km	min/mile
sea level	8:30:00.0	10:11.4	16:23.9
1000 ft (305 m)	8:36:52.1	10:19.6	16:37.2
2000 ft (610 m)	8:43:44.2	10:27.8	16:50.4
3000 ft (914 m)	8:50:36.3	10:36.1	17:03.7
4000 ft (1219 m)	8:57:28.4	10:44.3	17:16.9
5000 ft (1524 m)	9:04:20.5	10:52.5	17:30.2
6000 ft (1829 m)	9:11:12.6	11:00.8	17:43.4
7000 ft (2134 m)	9:18:04.7	11:09.0	17:56.7
8000 ft (2438 m)	9:24:56.8	11:17.3	18:09.9
9000 ft (2743 m)	9:31:48.9	11:25.5	18:23.2
10000 ft (3048 m)	9:38:41.0	11:33.7	18:36.4

Since I'll be running at 7000 to 10000 feet the whole time, I'll assume a handicap of 45 minutes to 1 hr 15 minutes, and then probably handicap myself another 30 minutes for the mountain climb and my recent fatigue of running 3 marathons in 3 weeks. I'm therefore going in prepped for the idea of running 10 hours 15 minutes. Let's see how this goes.

Again, I know to take what the race day gives me. But having an educated guess of how the day will go is a lot more settling than having a complete question mark over the whole race day, at least for this analytical mind! I'll see you on the other side of Pajarito Mountain!

Oh, and who has data from their own running to support or debunk this calculator for altitude changes? I'm really curious!