Sunday, June 28, 2015

Lessons learned on foot injury management and shoe design: Capping off a 100 mile training week in Hoka Challenger; Avoiding "Toe Spring" in running shoes

This weekend I capped off a 100 mile training week, peaking up for the 2015 Angeles Crest 100, with a 33 mile run yesterday and a 20 miler this morning up Mt. Wilson.

Yesterday's 33 mile run with my pal Alex started at the Lake Avenue trailhead and ascended the Sam Merrill Trail to the Mt Lowe railway, on to the summit of  San Gabriel peak at 6100 feet, and then down through Red Box to Switzer's, returning via Red Box to Eaton Saddle and  back down.  It was a fabulous, technical run with tons of climbing (7840ft!) in a run time of 6:09.  The 20 miler today was my traditional Sunday  fast hike-up/ run-down climb-fest on the Mt Wilson Toll road.  I felt solid and the running was fabulous!

But this weekend's training almost did not happen.

All through the last week I had been playing a game of tag with two increasingly painful foot problems:

  1. A problem in my left foot --symptoms being sharpish pain in the bottom of my foot mainly at the big toe joint--  which has been building over the last couple months.  This started, I believe,  with an unfortunate stone bruise while running technical trail in very lightly armored Merrell Trail Glove-1s.  (I believe this to be a case of case of sesamoiditis/metarsalgia --self-diagnosed!-- based on readings online, not a medical diagnosis). 
  2.  A two-week old case of severe pain in my right foot at the base of the second and third toes, that is particularly exacerbated when I put my weight on my feet with my toes dorsi-flexed (i.e. pulled up).  This is of course a problem  when running uphill!   Other positions that caused pain:  squatting on my heels  with my weight on the balls of my feet (think baseball catcher's position), or standing up weighting the ball of my foot with the toes flexed and my ankle pulled up off the ground.  The pain was mostly on the top of the toe joints (the dorsal side as opposed to the plantar side).  This new problem came on after  about one week of running in a new pair of Brooks Pure Grit 3 trail shoes.

What I had found was that the left foot pain would go away if I ran in the more heavily padded Brooks, but running in the Brooks was just killing my right foot!  Switching back to Merrell Ascend Gloves, the right foot pain was substantially palliated, but the left foot pain was exacerbated!  Also, walking barefoot, the pain in the right foot went away completely -  unless I weighted the foot as described above -  weighting the ball of my foot with my ankle lifted off the ground.

I pulled out a pair of Inov-8 Trailroc 255s from last year and by the end of the week these were the only shoe I could tolerate for running:  They alleviated the right foot pain quite a bit and the left foot big-toe pain was tolerable.  I took a rest day on Friday and walked in the Trailrocs, and was contemplating the prospect of scrubbing my planned heavy mileage  training weekend, just at the point where I need to be peaking up my mileage for the AC100 race coming up in 5 weeks.

What the hell?  What was it about the Inov-8s that seemed to be working and what was it about the Brook's that was so wrong?

Researching the problem I came across a thought-provoking article on shoe design mistakes, and in particular, an analysis of a shoe characteristic called "Toe spring":  Toe spring is the characteristic of most running shoes wherein the toe box curves up from the ground (think elf shoes!), so that one's toes while wearing a shoe with a lot of toe spring wind up in a very flexed position, pulled up off the ground:
Explanation of "Toe Spring" characteristic of running shoes

The problem with toe spring is that naturally, the toes are supposed to contact the ground!  Pulling the toes up exposes the metatarsal heads, the sesamoid bones, and the ligament capsules of the toe joints to quite unnatural stresses.

Here are photos of the Inov-8s, the Brook's and the Merrells that illustrate the differences:
Inov-8 Trailroc 255s:  Virtually NO "Toe Spring" (GOOD!) - rather stiff sole is absolutely flat, with moderate midsole cushioning.
Brooks Pure Grit 3:  Crazy amount of "Toe Spring"  (BAD!) with a very stiff sole. Lots of cushioning.
Merely Trail Glove 3:  Lots of "Toe Spring", but the sole is flexible and tends to straighten out when worn;  minimal cushioning
Merrill Ascend Gloves: Moderate "Toe Spring", minimal cushioning

Looking at these photos it seems clear why the Inov-8's were working for me and the other shoes were NOT:  The Inov-8 shoe design respects the anatomy of a normal human foot while the others simply do not!  I believe that the reason the Brook's were helping the left foot problem was simply due to their soft padding and relatively heavy armoring.   This was protecting the big toe metatarsal/sesamoids, but the stiff sole combined with the excessive toe spring was wrenching my right foot's toes up and creating the new problem on the dorsal side of the right foot toe joints.

In desperation, Friday after work  I drove over to the local Pasadena running store, Run With Us, to see if I could get a new pair of Inov-8s as the old pair I have is fairly worn.  It occurred to me that the midsole was fairly compressed--  I was thinking that in a  fresh pair, my left foot problem might be OK.  No luck:  The store was out of stock in my size.

Looking over my shoulder to make sure that I knew no one in the store,  I asked to try on a pair of Hoka One Ones, the Challenger ATR trail shoes.  After a few years of extolling the virtues of minimalist shoes and mocking my ultra friends who wore what I called "Hoka clown shoes", I was desperate enough to try them.  Given the irritated state of my feet it was clear that my weekend running plans would have to be cancelled unless I found a fix fairly radically different to what I have been trying.

Here is what the Hokas look like:
Hoka Challenger ATR
At first glance it would seem that the Hokas have a lot of toe spring-  but this is not correct.  Inside the shoe, the foot sits on a very flat, horizontal surface so that effectively there is very little toe spring.  What looks like toe spring is a design feature Hoka calls "meta-rocker" technology. The outsole curves up but the inside of the shoe where the toes contact, does not.  As a result, in these shoes, one can climb uphill with minimal toe dorsiflexion.  Just what I needed to deal with the right toe problem!

The Challengers have an extremely thick midsole (29mm at the heel) but a low heel-to-toe drop of 5mm.  The low heel-to-toe drop is a parameter that I have found important to preventing knee problems.  I was concerned about the massive midsole thickness,  however, while thick, the shoes are both feather light (as light as my Merrell Ascend Gloves) and the midsole in the Hokas is quite firm, not mushy at all, allowing for secure foot-plants.

I bought the Challenger ATRs and on Saturday morning I headed out wearing them, but with my old pair of Inov-8s stuffed in my backpack as a back-up plan in case the experiment proved disastrous.  I was fully prepared to scrub the run and turn around if the Hokas didn't work out.  To my great joy, I experienced no right foot pain at all, and the heavy midsole padding did a good job of protecting my left foot big toe joint.  I had a great 33 mile run.  This morning I ran 20 miles in the Hokas again, this time experimenting with a Pro-tec metatarsal pad in my left shoe to see about improving the protection of my big toe joint.  It felt great.  My running form is unaffected in these shoes-  forefoot strike with a high cadence and a short stride.

I will continue to be careful with this problem and continue icing the feet but it does seem at this point that I have a solution that will get me through my high mileage training phase while allowing the foot problems to settle down.   I am very relieved!

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