Educated Guesswork

Sean O'Brien 100K Race Report

Posted 2021-10-25

Last weekend I ran the Sean O'Brien (SOB) 100K in Southern California. This was a somewhat last minute backup race after Pine to Palm 100 miles was cancelled. There weren't too many 50M/100Ks in October[1] and my coach Emily Torrence won SOB back in 2017, so I was able to take advantage of her expert knowledge.

Overall this went well. I came in at 12:53, beating my 100K PR from from Ordnance 100K 2017 -- a much easier race -- by almost 9 minutes and my Tahoe 100K 2018 -- probably a more comparable event -- time by over 2.5 hrs. Generally, I stuck to my pre-race pace and fueling plan and hit my pre-race target of 12-13 hours. The basic plan was to run the first half at "long run" effort and then try to hold on the second half. I didn't quite succeed in this, but was reasonably close.

To orient yourself, here is the course and the hill profile. The circles on the course are mile markers, so you start at the far right, go all the way to the left, around the loop counter-clockwise, then backtrack. There's that out-and-back down to Bulldog and then you backtrack to the finish. The circles on the profile are "climb score", Runalyze's estimate of how hard the climb was.

Map Profile

[Screenshots from Runalyze]

Start to Corral Canyon [7.3 mi, +2270/-846 ft] #

Race start was at 5 AM and Sunrise is around 7:00, so we spent the first two hours or so in the dark. It was a bit warmer than expected, at mid-50s and rainy.

Pre-race I went back and forth on what to use for my headlamp: Most days I use a Petzl Actik Core [450 lm, 75g], which is good enough most of the time, but I also have a Lupine Piko [up to 1500lm, ~150g] which is substantially brighter and hence better if the footing is dodgy. A second consideration is that I wasn't sure whether I would need a headlamp at the end. Sunset is around 7:00 PM, so if I was on target, I wouldn't need one at all, but if I was way behind, then I might need it. My last drop bag was Bulldog at mile 50ish, and I didn't want to have to lug a heavy headlamp up a big hill, so I ended up using the Lupine from the start and then leaving the Actik Core in my drop bag.

This leg is a big climb, which went quite well. I ran nearly all of this, walking stuff that was technical or extremely steep. I deliberately let the lead pack go so I wasn't tempted to run with them, but felt like I was hitting my effort targets. At this point I mostly settled into the place I was going to be for the rest of the race, getting passed by maybe 3 people the rest of the day and passing one or two.

I hit the first aid station well ahead of schedule[2] at 1:23 (11:25/mi) and feeling strong. I mostly just ran through this, grabbing some fluid and moving on (0:24).

Kanan Road [6.3 mi, +1010/-1444 ft] #

This next section is mostly rolling single track and fire road. It was still dark at this point and I was definitely glad that I had brought the brighter lamp because footing was a bit dodgy in the low light. Other than that, this section was pretty straightforward and still quite runnable. I was still feeling good when I got to the aid station. I hit the bathroom, filled my bottles, and headed out quickly (3:57).

Zuma Edison Ridge 1 [5.4 mi, +1260/-997 ft] #

This next section is a rolling descent on single track followed by a moderate climb on fire road to the top of the ridge line ad. The fire road was pretty smooth and I was still keeping good pace here and ran pretty much this whole section. Unfortunately, it's about here that I started having pain in the inside of my left knee, especially on the climbs. This felt kind of familiar from a previous injury which turned out to be bursitus. Previously, it was bad enough that I couldn't run, so I was naturally kind of concerned about this, but it wasn't yet bad enough that I couldn't run.

There's a moderate descent followed by a short climb into the aid station, followed by a 3ish mile descent down into a lollipop with Bonsall at the bottom, so I just quickly grabbed some more fluid and headed out.

Bonsall [3.4 mi, +0/-1706 ft] #

As noted above, this next section is a 3.4 mile descent down to the Bonsall aid station. Pretty much this whole thing is on fire road so I was able to take it pretty fast (~8:35/mi). That part was good, but there were two problems:

  1. Every time it flattened out my knee started to hurt again.

  2. I started to feel pretty unstable in the shoes I was wearing (Salomon Pulsars). These are ultralight race shoes but they're designed more for speed and forefoot striking and the narrow heel is a bit unstable, at least for me.

I hit the bottom pretty worried about the knee and worried I might have to drop out. Fortunately, I was able to borrow a vibrating foam roller and work on the inside of the knee enough to be able to get moving again (4:26).

Zuma Edison Ridge 2 [7.76, +2910,-1184 ft] #

There's a long climb out of Bonsall back to Zuma Edison Ridge. This is actually two climbs, ~1600 ft, followed by a descent of around ~1000 ft and then another climb of ~1300 ft. It's not well shaded and generally quite sandy and rocky and I was regretting being in the pulsars, which have a pretty shallow tread and felt twitchy on the rock. I ran a fair bit of this but also power-hiked a lot as well. At this point I passed someone who had torn by me on a downhill at the beginning. Amazingly this was his first ultra and only his second race (the first was Pike's Peak Marathon), so I was fairly impressed that he was moving so well.

This whole section took almost two hours, but eventually I slogged my way to the aid station. This is the halfway point with more than half the climbing done, and I was at 6 hrs, so was feeling reasonably good about things and my knee wasn't much worse than before. At this point I figured it was time to start with Coke so I got some caffeine onboard as well as some electrolyte tablets. I drank some Coke at every aid station from here on in. This aid station was a bit long, in part because I had to fish some lube out of my bag to help a guy named Teague (sp?) who was getting some chafing (5:27).

Kanan Road [5.4 mi, +1037/-1283 ft] #

At this point we're just backtracking down the backbone trail to a previous aid station. This means a ~600ft climb followed by a step descend and some rolling terrain. At this point I noticed that Teague was more or less keeping pace with me even though I was running about half the climb and he was just hiking the whole thing. This made me think that I had slowed down enough (or the terrain was harder) so maybe I should be hiking more and I adjusted my strategy to hike more of the uphills.

Teague and another runner passed me on the downhill and I lost contact with them. At this point things were starting to heat up and I was definitely noticing some fatigue, which, combined with the shoes, was making me especially tentative on the descents. I had left a pair of Salomon S/LAB Ultra 3s (their long distance racing shoe) in the Kanan drop bag specifically against this eventuality, so I was able to change them out. Was still able to get out pretty fast (3:03).

Corral Canyon [6.4 mi, +1453/-974 ft] #

We're still retracing our steps back to the first aid station, so this is mostly on single track and generally uphill. It was still pretty warm at this point and I was doing a lot of hiking. The new shoes were a lot more stable which was a definite improvement, and my knee started to feel quite a bit better.

I made my way to the aid station, which was a slog, but I also knew that I had a long downhill ahead of me, so I mostly just needed to make it that far. I grabbed some more electrolytes, etc. and headed out (2:13).

Bulldog [5.9 mi, +486/-1946 ft] #

At this point I was really regretting not paying more attention to the course: I had remembered there being a long out-and-back with a descent to the Bulldog aid station, and then just turning around and coming back up. It's actually more complicated: first you go up a mile and ~400 ft, then down about 3 miles, and 2 miles flat, which is just psychologically harder than a long descent. The only good part here is that the aid station workers had told me it was 6.5 to Bulldog but actually it was less than 6, as I was informed by a runner coming up.

I was pretty tentative on the descent. It's quite steep (about the same as Kennedy Road in Sierra Azul) and a bit rocky and after breaking my rib a few weeks ago I really didn't want to fall again. I did in fact catch my toe a few times, but fortunately stayed upright, so at least that part was working. I definitely could have gone faster on the downhill if I hadn't been trying to be careful.

A nice part about an out and back is that you get to see everyone coming the opposite way. I counted 11 people in front of me, though based on talking to people at the finish, I may actually have ended up in 11th (still waiting for the results).

It's never a good idea to spend too much time in an aid station at the bottom of a hill, so I tried to make it quick. However, I did need a bunch of refills and I also took some time to work on my knee with their impact massager just in case [3:51]. Moved out with 2 bottles (1l) of sports drink and 1 bottle of water, figuring I would use the climb up to hydrate. I also grabbed my light though I didn't really need it, because I finished well before dark.

Corral Canyon [5.8, +1906/-495 ft] #

I ran the flat mile or two modestly hard and then just settled in for the long hike up to the top. Pace was actually pretty good here (14:00/mile for this leg) and this was just long. I did manage to get almost all the fluid in, which is good because I had been getting dehydrated (dark urine, etc.) Nothing much to report here other than finally made it to the top and took the mile long downhill back to the aid station.

I saw a lot of people coming the other direction as I was coming up and was able to tell them how far they had to go, which I had certainly appreciated coming down. The closest person behind me was about 2 miles back (and the person right in front of me was maybe .75 in front) so my position seemed pretty stable at this point. I saw the guy doing his first ultra at maybe 2 miles down the hill, so it looked like he had faded pretty badly, which wasn't too surprising as he had looked tired earlier.

Finally hit the aid station. Was definitely feeling a bit tired at this point and sat for a minute to grab some more electrolyte pills, adjust my shoes, fuel up, etc. (4:02).

Was feeling pretty good about my time at this point because I left the aid station at 11:26 and I figured 6ish miles would take 1:10-1:15.

Finish [7.3 mi, +833/-2277 ft] #

The way to the finish is some rolling single track followed by a really long descent, mostly on fire roads (remember, we're backtracking again, though I'd done this section entirely in the dark on the way out). Again, I was taking it really careful to avoid falling -- I did actually misstep once and have to put a hand down but it wasn't a real fall -- so I wasn't moving that fast in this section.

After the long downhill, there's a small rise (maybe a mile and 250 ft) followed by another descent into the finish. This is another case where I should have paid more attention to the actual GPS track instead of what the aid station workers or the course description said. My GPS was measuring 7.3 out and I thought it might have been error because they assured me it was only 6.5, but sure enough its actually 7.3. I had planned to push the last bit once I got off the steep downhill but I didn't really anticipate it being more like 1.5-2 miles, so that was kind of an unpleasant surprise. I was able to keep pushing right to the end, though, so I still had some gas. It's a good thing I decided to push, though, because with the extra distance if I hadn't I might have missed out in 13:00.

Retrospective #

Overall I think this went quite well. I was targeting 12-13 and got significantly under 13. My real stretch goal was a little closer to 12:30, but given that this is a big improvement on my previous PR and the uncertainties of the day plus my caution on the downhill this seems like a good result.

I might have started out a tiny bit hard, but given the cool temperatures at the start and how I was feeling I think it was generally reasonable. It's clear that the biggest place I lost time was on the downhills, where I was just really being super careful. If I hadn't been worried about my rib, I might have gone faster, but I also think I need to spend more time learning to descend fast. You're not just losing time; it's actually tiring to go slow. I also am not sure I made quite the right tradeoffs between running and hiking. I think I started hiking too late and then should have run some stuff I ended up hiking. Given how I felt at the end, I think I could have pushed some of the middle slightly harder, especially if I hadn't had to worry about being too fatigued to run downhill effectively.

I probably would have been better off going with the Ultra 3s from the beginning. The Pulsars are nice and light but I felt uncertain in them and I think it may have also contributed to my knee pain. I could also have worn the Sense Pro/4s that I used in Bigfoot and Yosemite. They are slightly lighter than the Ultra 3s. I decided not to put them in my bag because they don't have that much support I was worried about my ankles and so wanted to be sure that if I needed to change I had something supportive, but I could have just worn the Sense Pro/4s the whole way. It looks like Salomon will be bringing out a whole line of shoes with their new foam including a more stable Pulsar variant, so this may not be a compromise I have to make in the future.

My rib hurt for the whole second half of the race. I'm not sure if it's just not healing properly or if it's bruising from the way the pack was sitting. I'm leaning towards the second because it was also hurting this way about 6-9 months ago. Will need to debug this before my next event. Interestingly, it wasn't a problem in Yosemite, so perhaps something about the way I packed the front of the pack.

Nutrition generally went well. I was targeting 1l of sports drink/hr plus 100cal of gel or bar. Towards the end I was thirsty and not hungry so was probably closer to 300 liquid cal/hr in sports drink and coke. I was nauseated at the end but felt mostly OK during the event. Should have drank a little more because, as noted earlier, I was somewhat dehydrated. Did a pretty good job of keeping the aid stations short, but could stand to shrink it a little more still.

Summary #

Segment Distance Elevation Time Pace GAP
Corral 7.29 mi +2,270/-846 ft 1:23:08 11:25/mi 9:09/mi
Aid - - 0:24 - -
Kanan 6.34 mi +1,010/-1,444 ft 1:09:08 10:54/mi 10:05/mi
Aid - - 3:57 - -
Zuma 5.42 mi +1,260/-997 ft 1:01:10 11:17/mi 9:46/mi
Bonsall 3.43 mi +0/-1,706 ft 29:23 8:35/mi 9:31/mi
Aid - - 4:26 - -
Zuma 7.76 mi +2,910/-1,184 ft 1:51:34 14:22/mi 10:37/mi
Aid - - 5:27 - -
Kanan 5.40 mi +1,037/-1,283 ft 1:06:25 12:19/mi 10:58/mi
Aid - - 3:03 - -
Corral 6.37 mi +1,453/-974 ft 1:29:14 14:00/mi 11:56/mi
Aid - - 2:13 - -
Bulldog 5.91 mi +486/-1,946 ft 1:03:26 10:44/mi 10:21/mi
Aid - - 3:51 - -
Corral 5.84 mi +1,906/-495 ft 1:25:24 14:38/mi 11:11/mi
Aid - - 4:02 - -
Finish 7.32 mi +833/-2,277 ft 1:26:57 11:52/mi 11:16/mi

  1. Quicksilver 100K is actually the same weekend and is run on many of the trails I regularly run on in Sierra Azul but it just seems weird to pay to race on trails I usually train on for free. ↩︎

  2. I used Ultrapacer to estimate my times, but their algorithm seems to underestimate my speed on the climbs and overestimate on descents, as we'll see later. ↩︎


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