Wednesday, August 8, 2012

High-altitude running

Working out in Carbondale, Colorado was one thing: I was at about 6,000 feet elevation, and I found that after a week or so I could comfortably run 8-minute miles, or even a bit faster. But for the past week, We've been staying near Telluride, Colorado, at closer to 9,000 feet!

At this elevation, the air contains about 73 percent of the oxygen found at sea level. Contrast that to 81 percent at 6,000 feet. So I had a third again less oxygen than I had in Carbondale, and I could definitely tell the difference during my runs. An 8-minute mile on level ground was a real struggle, and even a 9-minute pace wasn't easy.

Part of this may be due to the fact that there really wasn't any "level" ground around the cabin where we were staying, and I was running on gravel roads, not pavement. Still, there's no question that running at this elevation was contributing to the difficulties.

The real question I was trying to answer as I ran in Telluride was how the elevation would affect my marathon at Crater Lake, which ranges between 6,000 and 7,800 feet.

I'd like to be able to complete that race in under 4 hours. If it was close to sea level, I think I wouldn't have much trouble doing that: There is less elevation gain and a similar loss to Blue Ridge, which I finished in just over 4 hours.

I've created a tentative plan for running Crater Lake: 9:00 miles on the flats, 10:30 on the uphills, and 8:00 on the downhills. That doesn't seem very fast, but considering that for most of the race I'll have less than 80 percent of the oxygen I have a sea level, I think it's pretty reasonable.

The last four miles of the race involves an even steeper hill, a 2-mile climb and descent on a gravel road, so I planned for 11:00 and 13:00 on the uphills and 8:30 on the downhills. 

When I arrived in Telluride I had less than two weeks left before the race, so technically I should have been in taper mode, decreasing mileage while maintaining training intensity. Maintaining intensity was no problem at all: the altitude and the hills took care of that. But I also wanted to do as much as I could to simulate the conditions of the race.

On Thursday my plan was to run a hard run -- normally during sea-level training I'd be doing tempo runs but there's not much point to that at elevation because you can't run very fast, so I wanted to replace it with some hills. As it turned out I didn't know the area very well and ended up with just one large hill. The half-mile hill gained 160 feet, and I had to stop for two walk-breaks. It wasn't ideal, but I still managed a 9:18 pace for the mile, so considerably faster than my planned marathon pace. I also kept it easily below 8:00 pace on the downhill mile, so overall it felt okay. However I was very tired after just 8 miles. My average pace for the run was 8:30, so next I wanted to see how I felt after running a 9:00 pace for a similar distance.

On Sunday was my last long run, a planned 90 minutes at an "easy" pace, so that seemed like a good time to try for a 9:00 pace. I slowed things down on a similar route to what I had done on Thursday, and felt pretty good. I arrived at the final hill, this time in Mile 9 instead of Mile 7, and decided to simulate one other plan I had for the race. For that last, steep hill, I had figured out that a 1-minute run, 1-minute walk should work out to a 12:30 pace. I wanted to see how that played out in reality, so I tried following the plan during the run. It was tough, but I could do it, recovering enough during the hard walking phase to run solidly later. The result was indeed a sub-12:30 pace.

I did feel a little better after my 10-miler than I had after my 8-miler at a slower pace earlier in the week, but still not great. That might have been more due to the fact that I had spent the entire previous day at an outdoor jazz festival than anything in my run preparation, but still....

It does seem that my plan for Crater Lake is at least plausible. What remains is to actually do it. I'll have a little more about my strategy for Crater Lake later in the week.

I'm making my way towards Crater Lake over the course of the week, and I'll be doing some easy runs in the morning just to stay loose.

Details of my last two more-difficult workouts are below.

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