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As I wrote earlier, many oversubscribed races use a performance-based qualification process as a way of selecting participants. What I mostly passed over, however, is whether different people should have to meet different qualifying standards. If your goal is to get the best people, you could simply just pick the top X%. However, if you were to do that, what you would get would be primarily men in the 20-40 age range. To give you an idea of this, consider Ironman Canada 2011, which had 65 Hawaii Qualifiers. If you just take the first 65 non-Pro finishers, the slowest qualifier would be around 10:17. This standard would have two amateur women, Gillian Clayton (W30-34) at 10:01.58 (a pretty amazing performance, since she's 18 minutes ahead of the next woman) and Rachel Ross (W35-39) at 10:12.17, and no man 55 or above.

If you're going to have a diversified field, then, you need to somehow adjust the qualifying standard for age and gender. The standard practice is to have separate categories for men and women and five year age brackets within each gender. (Some races also have "athena" and "clydesdale" divisions for women and men respectively who are over a certain weight, but at least in triathlon, these are used only for awards and not for Hawaii qualifying purposes.) However, it's also well-known that these categories do a fairly imperfect job of capturing age-related variation: it's widely recognized that "aging up" from the oldest part of your age group to the youngest part of the next age group represents a signficant improvement in your expected results.

UPDATE: I forgot to mention. Western States 100 has a completely gender neutral qualifying standard, but it's comparatively very soft.

One of the common patterns in endurance and ultra-endurance sports is to have one or two races that everyone wants to do (the Hawaii Ironman, the Boston Marathon, Western States 100, etc.) Naturally, as soon as the sport gets popular you have more people who want to do race X than the race organizers can accomodate. [Interestingly, this seems to be true no matter the size of the event: Hawaii typically has around 1800 participants, Boston over 20,000.] As a race organizer, then, you are faced with the problem of deciding how to pick the actual participants from those who have the desire to participate.

The first problem seems to be deciding what to optimize for, with the two most common objectives being:

• Choose fairly among everyone who wants to do the race.
• Choose the best athletes.

Fair Selection
The easiest way to choose fairly is generally to run a lottery. You take applications for a race up until date X and then just draw however many entrants you want out of that list. [Note that there is always a yield issue, since some people register who never show because of injuries or whatever, so the number of actual participants is never totally predictable.] For races which are only mildly oversubscribed, what's more common is take entries up until you're full and then close entry under the "you snooze, you lose" principle. Ironman Canada does this, but now it basically fills up right away every year so you more or less have to be there the day after the race when registration for the next year opens up.

Merit-Based Selection
Choosing the best athletes is a more difficult proposition, since you first need to identify them. You might think that you could just have a big qualifying race with everyone who wants to race and just pick the top X participants, but this clearly isn't going to work. Since the size of the target event is generally (though not always) set to be about the maximum practical size of a race, if you're going to pick out the top people to race in your target event, the qualifying event would have to be much much larger, well beyond the practical size. Instead, you somehow have to have a set of qualifying races and draw the best candidates from each race. In some cases this is easy: If you are drawing national teams for the world championship, you can just have each nation run its own qualifying race and since each such race only needs to draw from a smaller pool, it's still manageable. However, many events (e.g., Ironman) aren't laid out among national lines so this doesn't work.

There are two basic strategies for drawing your qualifying candidates from a number of races. First, you can have a qualifying time. For instance, if I wanted to run the Boston Marathon, I would need to run some marathon under 3:10. Obviously, there is a lot of variation in how difficult any given race is, and so this leads to people forum shopping for the fastest race. It's extremely common to see marathons advertised as good Boston qualifiers. The key words here are "flat and fast" (A qualifying race can only have a very small amount of net downhill, so non-flat means uphill,which slows you down.). Obviously, a qualifying time doesn't give you very tight control over how many people you actually admit, so you still have an admissions problem. As I understand it, Boston used to just use a first-come-first-served policy for qualifiers but in 2012 they're moving towards a rolling admissions policy designed to favor the fastest entrants. That said, At the other end of the spectrum, the Western States has their qualifying time set so that there are vastly more qualifiers than eventual participants (it looks to me like it's set so that practically anyone who can finish can qualify [observation due to Cullen Jennings]) and they use a lottery to choose among the qualifiers.

The other major predictable approach is that used for the Hawaii Ironman. The World Triathlon Corporation (who runs Hawaii) has made certain races "Hawaii qualifiers" (my understanding is that a race pays for this privilege) and each race gets a specific number of slots for each gender/age combination. The way that this works is that if there are 5 slots in your age group, then the top 5 finishers get them. If any of those people don't want the slot (for instance they may have already qualified) then the slots roll down to the 6th person, and so on. all of this happens the day of or the day after the race and in person. This method gives the race organizer a very predictable race size but poses some interesting strategic issues for participants: because participants compete directly against each other for slots, what you want is to pick a qualifying race that looks like it is going to have a weak field this year. Unfortunately, just because a race had a weak field last year doesn't mean that that will be true again, since everyone else is making the same calculation!

Arbitrary Selection
One thing that I've only seen in ultrarunning is invitational events with arbitrary (or at least unpublished) selection criteria. For instance, here's the situation with Badwater:

The application submission period begins on February 1, 2012 and ends on February 15, 2012. A committee of five race staff members, one of whom is the race director, will then review and rank each application on a scale of 0 to 10. The ranks will be tallied on February 18 and the top 45 rookie applicants with the highest scores, and the top 45 veterans with the highest scores, will be invited (rookies and veterans compete separately for 45 slots for each category). At that time, or later, up to ten more applicants (rookie and/or veteran) may be invited at the race director's discretion, for a total of approximately 100 entrants, and 90 actual competitors on race day.

I guess that's one way to do it.

I've now completed two different flavors of ultradistance event, Ironman-distance triathlon and a 50 mile trail race. In terms of time these events are fairly comparable—my Ironman personal record (at Ironman Canada) was 10:13 and my time at the Firetrails 50 was 10:10—so I feel like I have some basis for comparison.

Intensity
For my money, the biggest difference is that—at least for age groupers—Ironman seems to be raced at a much higher level of intensity than trail running. I think this can be attributed to a number of factors, some inherent and some cultural.

First, running 26 miles on road is really different than running 50 miles on dirt trails. Just covering that much distance on your feet, and having to constantly adapt to changing footing is really hard on your legs. Remember that even though the time in the Ironman is longer, a lot of that is on the bike, which isn't anywhere near as hard on your legs. Then there's the elevation change: the Ironman Hawaii run course has 400 or so feet of elevation gain; the Firetrails 50 run course has 7800 feet. When you put these two factors together, my experience is that you end up feeling a lot more beat up at the same intensity level; I was about as sore the day after Firetrails 50 as I've been after any Ironman, even though I went a lot easier. I don't think there's any way I could have raced a 50 mile trail event at the same level of perceived effort (e.g., heart rate) as I would an Ironman.

Conversely, you don't need to race a trail event the same way. Every halfway decent long course age group triathlete's goal is to qualify for Ironman Hawaii. The comparable objective in trail running is the Western States 100 (There are other big ultradistance running races, but they tend to be invitational only, rather than having clear qualifying criteria.) However, the qualifying procedures are radically different: Hawaii qualification is by place; each race gets some number of slots for each age group and the top N finishers who want to go to Hawaii get those slots. This means that if the person in front of you is in your age group, you have a very direct incentive to finish ahead of them, even if you're nowhere near actually winning your age group. By contrast, Western States qualification is by time: Every athlete who meets the time cutoff can apply and a lottery is used to decide who actually gets to race. This means you have no direct incentive—other than pride—to beat anyone in particular, since you can't stop them from qualifying (unless you trip them or something). Moreover, the Western States qualifying times are comparatively soft; out of 193 finishers at Firetrails 50, 140 qualified. Hawaii qualification rates are more like 10%. This means that you don't need to kill yourself, you just need to have an OK day. That's why you see people walking the aid stations in trail runs; good age groupers don't walk triathlon aid stations unless they're basically melting down.

Social Structure
Compared to the trail running, triathlon is intensely competitive. Obviously, trail running is competitive at the upper levels, but even mid-pack triathletes can be super-aggressive. I've been kicked, shoved, and swum over plenty of times, even in local races where I'm not in contention for anything. The bike and run tend to be less bad because people are more spread out, but there's still plenty of jockeying for position. This happens in road racing, too; people generally don't push too much, but I've definitely had to fight my way through a crowd plenty of times and there's a lot of bumping at the start. By contrast, trail running just seems a lot more mellow, even in situations that are inherently just as crowded.

I don't have a complete explanation for this. I'm sure it's partly just cultural, but I suspect it's also the setting you're in. Even nice road races and triathlons aren't typically in places that are that interesting. If you want to run on the Boston marathon course, nobody's stopping you, and to be honest, I'd describe the Ironman Hawaii course as more grim (20+ miles of asphalt and lava fields) than scenic. The only real reason to do the race, then, is to compete. By contrast, trail runs tend to be in nice places, often ones where it would be inconvenient to do a long run because you couldn't resupply yourself easily. This means you get a different, less competitive, class of people. Moreover, because the terrain is challenging and you're in the middle of nowhere, I think that people feel more like they're in it together.

Price
One more thing: trail racing is super-cheap. Even a cheap Ironman, like Vineman, costs $350 in advance and $450 on short notice. Ironman Canada is $675. Plus, if it's out of town you end up paying $200-300 to get your bike there. I paid $120 at the last minute for Firetrails 50, and you can put your shoes in your carry-on. I'm not blaming the people who run triathlons: it's an expensive sport to put together. But that doesn't mean it's not nice to race on the cheap.

Back in 2008 I was forced to DNF at mile 18 of the Dick Collins Firetrails 50 due to an ITB issue. 2011 has been a pretty good year in terms of training, so I thought maybe it was a good time to give it another shot. I knew going in that I wasn't really ready: I've been increasing my training load but prior to September 2, my longest training day of the year had been 17 miles with about 2000 ft of climbing, which I'd normally consider barely adequate for a 50K, but not for 50M, but after the PCTR Santa Cruz 50K was cancelled, I went looking for another event and there Firetrails 50 was on the schedule.

Still, I was pretty iffy, and my original plan was to see how I felt on my long run September 2 (19 miles, ~2500 ft of climb) but then when I went to see about registering on Saturday, I noticed that the race was already full. I emailed the RD to see about a cancellation, and (unsurprisingly) the scarcity effect kicked in and I went from being ambivalent to actually wanting to race, so when I heard there was now a slot, I signed up. However, after Sunday, my hamstrings, which had been gradually tightening up, got super tight and no amount of stretching seemed to help. Luckily, I was able to get a last minute appointment with Joy at SMI; she didn't fix me completely, but did manage to get my legs loose enough that I figured I had a reasonable shot, especially if I kept up with yoga and stretching.

The race itself went fairly smoothly. I went out very conservatively, at around 10 minutes a mile. [This pace is a little misleading; you run the flats and downhills and walk the uphills, so you're actually not running 10 minute miles; you run like 8:30 or so, but with the walking it averages out.] Of course, over an event this long there are always a few snags:

• There was a bee hive somewhere around mile 10 and I and pretty much everyone else got stung.
• Around mile 15 the tape on my nipples started to come off and I ended up with quite a bit of chafing. Luckily, I was able to score some band-aids and duct tape at an aid station (the duct tape because practically nothing sticks to wet skin) and this mostly solved the problem though I felt some discomfort the rest of the way.
• Around mile 27 or so, something went wrong with my left heel and I spent the next mile or so wincing every time I landed wrong. Eventually it resolved itself, though, and I ran the rest of the way without incident.

Around mile 40 or so, I started to get pretty confident I would finish, but I stick with a conservative game plan until mile 45, at which point I started to press the pace a bit. Obviously, I was pretty tired, but with only 5 miles to go and feeling like I was at maybe mile 10 of an ordinary day, I figured I could afford to push it. I blew through the 45.5 aid station without stopping and decided I'd just run the rest of it. I didn't have a GPS and there aren't really mile markers, but I suspect I was running about 8:30 pace continuously, and I passed maybe 10 people over the next 5 miles, and did the last mile or so pretty hard (maybe 8:00 or 7:30 pace). My eventual finishing time was 10:10 and change. (I don't know exactly because the results are screwed up and have me inacurrately at 10:34, which is definitely wrong.) This is easily good enough to qualify me for Western States (the cutoff is 11 hours for a 50) so I'm pretty satisfied with this time. I'm not sure if I really feel like doing Western States, but it's nice to know I could sign up if I wanted to (there's a lottery to determine who actually gets in).

Last week, Brian Korver and I spent a couple of nights backpacking in Sequoia National Park, starting from the Mineral King trailhead, and doing the Little and Big 5 Lakes loop (pics).

Just getting to Mineral King was actually somewhat challenging. I didn't realize that the ranger station closed at 4 and there's no after-hours way to get a wilderness permit. Since it's s 5+ hours from Palo Alto and we left at 10:20, this didn't leave us a lot of slack, especially with the last 23 miles being on a winding, blind, one-lane road where I wasn't able to go faster than about 16 mph. We finally got to the ranger station about 3:30, got our trail passes, and were on the trail around 4:40. Our first day we climbed out of the valley, over Timber Gap, and got as far as the Cliff Creek campground/trails junction. This is about 5-6 miles and about 1500ft of ascent (not much net elevation change, though), so a good start.

The second day was the big one: we had to go over Black Rock pass (11670ft) the first of the two major passes on this route. The ascent here was a real slog, largely because it's something like 5-6 miles of climbing from the campsite, getting progressively steeper and ending in some really steep switchbacks in the last mile or two, so you just feel like you've been climing forever. All-in-all I prefer things to be flat and then steep rather than sort of gradually ramping up like this. Anyway, we got to the top around 2:30 (after leaving camp at 8:45), so not exactly a record. We hung out for a while and then started the fast downhill to the Little Five Lakes and managed to haul ourselves as far as the Sawtooth Pass trail junction (estimated mileage for the day 12-14). The campsite at the junction is nice, but what wasn't nice was that we were attacked by mosquitos as soon as we stopped. A coating of DEET and a fire quickly solved this problem, though.

On the third and last day, we had to ascend Sawtooth Pass. Since we were already at 9580 ft, and Sawtooth is at 11630, this wasn't that big a deal in terms of elevation gain, but the challenge is that the trail over Sawtooth Pass is unmaintained. Our guidebook claims that there are a lot of trails, but the situation on the ground seemed a bit different. The terrain is basically a huge boulder field on top of rock with a few patches of gravel and sand. There's no obvious trail but instead some kind soul (or souls) has laid something like 50-100 cairns indicating the general direction of the trail. At the beginning it wasn't even that clear which notch we were going through and we'd thought we might have to eventually navigate with compass and topo, but the cairns led us right up to a series of switchbacks over sandy trails going right to the pass. The way down, also unmaintained, was totally different and rather more brutal, consisting primarily of loose sand and gravel, with the result that we spent almost as much time sliding and arresting our slides as walking. Eventually, we got to Monarch Lake and the regular trail and then there was just the long descent back to the car.

I love the High Sierra, but I think I would hesitate about doing Mineral King again. The drive to the ranger station is really unpleasant and worth about another hour of freeway driving, so that's a real negative. Also, I prefer a bit more privacy and we saw a lot of people, to the point where there was some contention for campsites the first night— and this wasn't even on the weekend. Also, apparently if you go at the wrong time of year, marmots eat your car.

I recently started biking again and in the interest of being able to more accurately measure my workouts, I moved my SigmaSport BC1100 bike computer from my race bike onto my training bike. Like basically all bicycle computers from the pre-GPS era, the BC1100 is of the wheel magnet/sensor loop variety: you mount a magnet to one of the spokes and and a sensor to the fork. Every time the magnet passes by it induces a current which is transmitted to the computer.¹ Of course, this mechanism just measures rotational velocity (rotations per second). In order to measure road speed you need to know the circumference of the wheel and as, the battery had run out so whatever calibration I used to have was long gone.

If you read the manual for a typical bike computer you'll discover not just one but many calibration techniques arranged in a hierarchy of both accuracy in inconvenience that goes something like this:

• Look up your wheel size in a table.
• Measure the diameter and multiply by 3.14.
• Roll the bike one wheel rotation and measure the distance traveled.
• Roll the bike one wheel while sitting on it (to compress the front tire the way it would be if you were riding it) and measure the distance.
• Roll the bike N rotations (plus sitting in it, etc.), measure the distance and divide by N.

Regardless of the technique, the basic principle is that perform the above procedure, get the circumference, and enter it into the computer. In the specific case of the SigmaSport, you want the circumference in millimeters, so for a typical 700C-sized road wheel, you want something around 2100mm. Anyway, I dutifully performed the procedure as specified (see instructions here) and entered the desired number (2037) into the computer. So far so good, except that once I actually got on the bike, it reported that I was going about 25 miles an hour on average and 30 mph on the flat. Seeing as typical time trial pace for amateur athletes is around 25 mph and I wasn't even breathing hard, either I was ready to sign up for the Tour de France or something was screwed up with the calibration. The second of these seemed more likely.

A little searching around the InterWebs quickly revealed the problem: this model doesn't have an internal adjustment for English versus Metric, so you need to divide by 1.6ish to convert to miles/hour. I guess it was cheaper to just have the units setting change the labels than to actually include a circuit that divided by 1.6. Turns out that this actually is on the SigmaSport web site, though not in the owner's manual. Unfortunately, it's labelled "Attention BASELINE 400, BASELINE 700, BASELINE 1200 & BASELINE 1200+ owners!". which doesn't really help, since I have a BC1100. Outstanding!

^1. The really cool Jobst Brandt-designed Avocet cyclometers instead used a ring of alternating polarity magnets mounted around the hub, allegedly for better precision. They don't seem to be available any more.

Last time I reported on my experience running with VFFs things were going pretty well. I wrote:

Bottom Line

I suspect I'd be able to run much longer in VFFs (and I'll try a 10 this weekend), but given how much trouble I had when I ran on grave [gravel --EKR] of the wrong size, I'm not sure I would want to do something like an ultra, where I couldn't turn around and didn't know that the surface would be good. In view of that, I'll probably start mixing it up more to make sure I still can run in shoes if I want to.

Since then, things have taken a turn for the worse. About 10 weeks ago I felt like my overall fitness was good enough to start introducing intervals back into my training plan. I started out relatively easy with 1/2 mile repeats and thing were going well. In keeping with my "mixed footwear" strategy I was trying to run something like:

Day	Workout	Surface	Footwear
Tuesday	Intervals	Asphalt	Inov-8 295s
Wednesday	Easy 3-5	Asphalt	VFFs
Friday	Moderate 5-7	Trails	VFFs
Sunday	Easy (8+)	Trails	Inov-8 295s

This was going OK and then after one interval workout (note: regular shoes) I noticed pain in my right foot at the first metatarsal-phalanges joint (where the big toe intersects the foot) and spreading across the metatarsals towards the little toe. wearing regular shoes. I'd noticed some pain like this before right when I first started running in VFFS, but it went away. Figuring it would go away again and not wanting to interrupt my workout plan I tried my Wednesday run as planned, but only got about 1/2 mile before I had to turn around and walk back; every impact hurt.

At this point I knew I had an injury but not how bad it was. I limped around for a day or two but then it seemed to get better so I waited a week and then tried a two mile run which had a little bit of discomfort but was mostly OK. I decided to try my ordinary Friday run (you've probably heard endurance athletes are stupid) but with Inov-8s instead of VFFs so I got some shock absorption. Bad idea. About 2 miles in I was in bad enough pain that I couldn't run at all (thanks to Kyle Welch for convincing me that running in intense pain was bad) and had to walk the two miles back. I spent the next 3-4 days barely able to run at all. Since then, I haven't been brave enough to run more than 2-3 miles at a stretch and even after doing that, I have discomfort or not pain. Visits to doctors produced some nonspecific diagnoses—possibly sesamoiditis, possibly tendonitis—and the all-purpose referral to PT, the go-to-plan for hard-to-diagnose joint-related injuries. We'll see if that helps.

It's obviously tempting to attribute this to the VFFs. The evidence for that view is that you tend to push off a lot harder with your toes, that it's a new injury occurring after a change in training regime, that I was experiencing pain there even before the acute injury, and that walking around the house barefoot seems to hurt more than wearing shoes.. The evidence against that view is that the actual acute injury happened after running in regular shoes and that it happened after a substantial change/ramp-up in training load, which is often a cause of injuries. I don't have an answer here and it's clear that—since we don't even really know what the problem is—the doctors don't know either. Once I'm able to run again in regular shoes I'll reassess whether I want to try minimal footwear again. For now, I'm supposed to stop running and wearing stiff-soled shoes all the time, so the question is kind of moot.

Ever since I got my VFFs, people have been asking me whether I ran in them and I'd always give the same answer: I haven't been brave enough. After I ran into Phil Stark, though, who does ultras in his huaraches, I figured I'd give it a try.

Rather than slowly transition, I decided to just switch over to Vibrams completely (this was Phil's advice and I had injured my shoulder, so couldn't do too much mileage anyway). That was about 6 weeks ago and I'm now at the point where I can comfortably go up to 7-8 miles, either on trails or road, and I feel like I have a long enough baseline to report back.

The Transition
It wasn't that hard for me to transition. I started with really short, with a mile or so, and then worked my way up over the course of a month or so. If you're a foot striker you need to completely alter your stride so you land either mid or forefoot (this is pretty much the point of going barefoot). I started out mostly on asphalt, which you would think would be pretty hard without any cushioning, but it really forces you to concentrate on your stride: one or two (incredibly unpleasant) heel landings on asphalt with no cushioning teaches you real fast to adjust your stride. Anyway, once your stride adjusts and you learn to land softly, I at least didn't find that there was much trauma to my foot. At around week 3 or 4, I started to get some pain in the metatarsals of my right foot, but that mostly went away after a few more weeks.

Instead of the foot, the primary adjustment was in the calf. Because you land on the forefoot, and seem to push off more by extending your foot, it seems like you put a lot more stress on your gastrocnemius. For the first month or so my calf and achilles tendon would be sore after each run, and at least once I had my right calf completely lock up and I was limping for a few days. This has mostly gone away by now, however, and I feel pretty comfortable up to reasonable distances.

Surface and Terrain
I've now run in VFFs on a whole bunch of different surfaces. Dirt trails are the best, then grass, then asphalt, and then gravel. Basically this is an issue of cushioning: with VFFs you're much more sensitive to how hard the surface is and grass and dirt are just nicely comfortable and springy. (Note: I prefer dirt even with a real shoe). Asphalt gives you a harder landing and so is less comfortable, but basically fine as long as you are actually landing OK. The problem with gravel is that as the size of the rocks starts to get bigger you start to have to really watch your landing: coming down hard on a sharp rock the size of a golf ball can be quite painful.

Climbing hills is good: you would naturally tend to land on the ball of your foot anyway, so it doesn't require much of an adjustment in your stride. By contrast, going down is bad because you would naturally tend to heel strike so you need to really overcompensate to avoid that. And of course since you tend to strike relatively hard going downhill anyway, this is doubly bad. Even now I tend to come down harder than I would like.

Road Hazards
The biggest problem with running in VFFs as opposed to shoes isn't the routine pounding but rather pebbles, rocks, acorns, etc. The soles are just too thin and flexible to protect you from this kind of impact. You can't always avoid stepping on rocks, but when you're running on a basically flat surface you can mostly see them in advance and when you do accidentally step on one, you usually notice before you've put your full weight on it and can just pull your foot back before you've done any real damage. I've only really managed to hurt myself twice: a week ago when I stepped on a small pinecone but landed on the side of my foot rather than the ball and wasn't able to correct. Then yesterday I want running on the baylands trail and there were just so many rocks that I couldn't avoid all of them and so landed pretty hard on a few.

Even in those two cases, I didn't do any permanent damage, just hurt a lot immediately and then ached for the next 5-10 minutes. It feels fine now, though and I don't see any bruising.

Other Issues
People often ask me about running with shoes with so little support: I have incredibly flat feet and I've never really found that having a lot of support did much for me; I find it more comfortable to just let my feet pronate completely the way they want to, even in normal running shoes. I don't know what VFFs would be like for someone with normal arches.

While I wear socks with regular shoes, I don't wear them with VFFs (you can wear Injinjis), and this hasn't been a problem for me. I have one friend who tends to get a lot of blisters with VFFs, but this hasn't been a problem for me at all (and I have gotten blisters with other shoes, so it's not like my feet are especially tough). I suspect this is primarily an issue of fit. For longer runs, it seems like I might be getting a few hotspots and I've been trying to slather on some Hydropel as a precaution.

You need to be a bit careful about stubbing your toe. There's not much protection and if you scrape the top of your toe, you can tear through the thin nylon at the top or peel the rubber sole away. I've got a small tear above my big toe. So far it's not expanding but I've ordered a new pair just in case.

Bottom Line
I suspect I'd be able to run much longer in VFFs (and I'll try a 10 this weekend), but given how much trouble I had when I ran on grave of the wrong size, I'm not sure I would want to do something like an ultra, where I couldn't turn around and didn't know that the surface would be good. In view of that, I'll probably start mixing it up more to make sure I still can run in shoes if I want to.

A persistent problem at races is long lines for the portapotties. I've actually missed the start of races because I was waiting in line. I've often wished that races would sell some sort of premier access where you would pay a little extra on your race fee and get to use special portapotties. (This is effectively Odzlyko's Paris Metro Pricing idea applied to a different kind of uh, resource.) Actually, what I would probably prefer would be a guarantee that the race would have an extra premier toilet for each X racers that paid for premier access.

Anyway, the New Orleans Rock and Roll Marathon seems to have implemented a more elaborate version of this:

To get your race off to the best possible start, we'll have comfortable, climate-controlled restroom trailers set up at the starting line. Running water, flushing toilets, and some Run Happy® surprises await.

To access this pre-race luxury, you'll need to snag a Brooks VIP Porta Potty pass in one of two easy ways:

1. Head to Varsity Sports between 2/1 and 2/27 and purchase $50 in Brooks or Moving Comfort apparel or Brooks shoes. Offer valid at both Varsity Sports locations.

OR

2. Come to the Rock 'n' Roll Mardi Gras Marathon™ & 1/2 Marathon Health and Fitness Expo on Friday 2/26, or Saturday 2/27, and purchase $150 in official Rock 'n' Roll Marathon merchandise, Brooks apparel or shoes, or Moving Comfort apparel.

Either way, you'll receive a sticker for your race bib. The sticker is your race-day pass to Brooks' VIP Porta Potty, to be expertly staffed by Varsity Sports volunteers and Brooks employees,

It's hard to figure out how much this really costs: I don't wear Brooks shoes, but presumably I could find some Brooks gear that would be comfortable, so figure like 20% of the amount you're expected to spend, which isn't so bad. Anyway, I've got no objection to emptying my bladder in comfort, of course—and the portapotties at races can get pretty bad—but really my priority is being able to go without having to wait. I'd be interested to hear from anyone who was at this event and used this service how long the line was.

Jennifer Leigh sent me a pointer to this article suggesting that running shoes put more stress on your legs.

Sixty-eight healthy young adult runners (37 women), who run in typical, currently available running shoes, were selected from the general population. None had any history of musculoskeletal injury and each ran at least 15 miles per week. A running shoe, selected for its neutral classification and design characteristics typical of most running footwear, was provided to all runners. Using a treadmill and a motion analysis system, each subject was observed running barefoot and with shoes. Data were collected at each runner's comfortable running pace after a warm-up period.

The researchers observed increased joint torques at the hip, knee and ankle with running shoes compared with running barefoot. Disproportionately large increases were observed in the hip internal rotation torque and in the knee flexion and knee varus torques. An average 54% increase in the hip internal rotation torque, a 36% increase in knee flexion torque, and a 38% increase in knee varus torque were measured when running in running shoes compared with barefoot.

Seeing as hip, knee, and ankle are major running injury sites— in fact, practically every major running injury I've ever had has been either at the knee or the ankle—this seems like it's something to pay attention to. The authors recommend that "Reducing joint torques with footwear completely to that of barefoot running, while providing meaningful footwear functions, especially compliance, should be the goal of new footwear designs." I already wear a relatively compliant shoe, the Inov-8 295, and while I don't have any data, it seems to have had a positive impact on a persistent ankle injury that has plagued me for years. I'd be interested to see this study repeated with a shoe deliberately designed to be as barefoot-like as possible like the Inov-8.

I do have a pair of the Vibram FiveFingers shoes, and while the advertising literature clearly suggests that you can run in them, I haven't really been brave enough to try it. There seem to me to be two issues here: First, the soles provide some protection but they're pretty flexible; I'm not sure that if you stepped directly on a rock it wouldn't be unpleasant. So, it seems like you would have to be a bit careful on trails. By contrast, asphalt is so unforgiving you would really need to have ideal form in order to avoid having some pretty serious impact forces. I'm still planning to go for a short run on a trail at some point, but I figure on taking it slow.