Shoe Modifications

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Clockwise from the top: Nike Free 3.0(early version) cut open more than most to form a 'running sandal', Saucony Hattori, NB Trail Minimus, Nike Free 3.0and the non-minimalist Hoka.

I cut open the toe box of nearly every shoe I run in to prevent blisters and to improve comfort. I started doing this to prevent blisters on ultramarathons, but over time I found that an open toe box allows my feet to move more naturally. When you run, your toes will tend to splay out at toe off, something that is inhibited by most running shoes. Of course, most people are reluctant to take a knife to their expensive running shoes, so I recommend trying get on an older pair of shoes that are close to the end of their life. This allows you to experiment with relatively little consequence. While cutting open the toe box can dramatically improve your comfort, there are limits to what it can do. If the toe box is too small, then your feet will hang over the edge of the midsole. A common concern with cutting open the toe box is getting debris into your shoe. My experience is that this is only a problem when walking, or running through undergrowth. It's extremely rare for me to get something in my shoes while running. Running through boggy ground is far more of an issue, but I have a fix for this below.

1 Why Cut Open the Toe Box?

There are several reasons for cutting open the toe box, from simple blisters, to the prevention of bunions and plantar fasciitis.

1.1 Blisters

I've worked on many runners' feet and found that the traditional shoe shape causes blisters between the toes. This is noticeable in Hoka shoes, but it occurs in others. Wearing toe socks like Injinji can help reduce the friction between the toes, as can taping the toes. Sadly, this also reduces the room in the toe box as it pushes the toes further apart, thus increasing the pressure. Cutting open the toe box relieves the pressure and I've not had a toe blister issue with an open toe box.

The Hoka Shoes seem to have a distinctive blister pattern, with the blisters forming between the big toe and the next toe, part way along the toe. Blisters also occur between the little toe and the next toe along.

1.2 Bunions

A bunion (hallux valgus) is a deformity of the joint between the foot and the big toe, where the toe is bent towards the other toes. Shoes that constrict the toes are believed to be a trigger for bunions, and the rise of pointed shoes in the late medieval period coincides with bunions in the skeletal remains from that time[1]. Though bunions occur only in shod populations, only a subset suffer from the problem, suggesting there may be other causal factors[2][3]. Cutting open the toe box relieves most of the pressure that constricts the toes.

1.3 Plantar Fasciitis

The plantar fascia are thick bands of connective tissue that support the arch of your foot. These bands can become painful, a condition called Plantar Fasciitis, or just PF. Plantar Fasciitis is common, with an estimate of 10% of the population suffering at some point[4]. The plantar fascia supports the foot, forming a link at the bottom of the triangle of bones that are the arch of the foot (see the image below.) The tension on your plantar fascia depends on the position of your toes. If your toes are raised up, this tensions the plantar fascia as shown below, something referred to as the windlass mechanism[5]. This windlass mechanism also shortens your foot, raising the height of your arch, and both mechanisms strengthen your foot. Wearing shoes can prevent you raising your toes. This inhibition of the windlass mechanism may be a cause of plantar fasciitis[6]. / [5] [4] [6] [[File:Plantar Bewegung.png|center|thumb|300px|

2 What About Morton's Toe?

Morton's toe is where the big toe appears shorter than normal, as shown below. While a traditional running shoe has more room for Morton's toe, it still lack the room for the toes to spread and flex, so modification is beneficial. File:Mortons Toe.jpg

3 What About Barefoot or Sandals?

It's often suggested to me that rather than cutting open my shoes, I should run barefoot or in sandals. This is a bit like suggesting that instead of opening the windows in your car, you should ride a motorbike. Cutting open a running shoe gives you the benefits of the cushioning, protection, and grip of a running shoe, without the problems. A correctly designed shoe wouldn't need cutting open. It would have a toe box wide enough for your toes to splay, which even Altra shoes lack. It would also have enough height for your toes to flex and strengthen the foot, which no shoe does. A properly designed shoe would look quite strange, and probably wouldn't sell, so it will be a long time coming.

4 How to Make the Cut

It's critical to know where to cut the toe box so I've used an x-ray image to give you a sense of where the cut lines are in relation to your joints. The most critical part of the cut is where it begins at the sides of the shoe. I've found the best cart starts just ahead of the metatarsal joint. This is just in front of the bulge that forms the ball of your foot on the inside edge. This ensures that the shoe is in contact with the main part of your foot, and only your toes are free. If you cut too far back, the shoe will be excessively loose, and likely to rub on the edge of the ball of your foot. If you cut too far forward then your toes will rub as they splay. The other end of the cuts, at the front of the shoe, is far less critical. I simply cut so that I remove the material that would touch my toes, while aiming to leave a bridge that is far enough away from my toes that it would cause a problem. Some runners don't bother leaving a narrow bridge to the front of the shoe, but I prefer to leave it in place as I find it a little more comfortable.
Mark the line you want to cut with a marker that will show up clearly. Err on the side of cutting too little as it's easy to remove a little more later. With practice you get to know where to cut on the first go, but beginners may need to cut conservatively then go for a short run to see how it feels. Typically just a few minutes will tell you all you need to know. You can then repeatedly cut a little more and try again until you happy.
Make the initial cuts with a sharp knife. Be cautious at this stage, as you may have to press quite hard to penetrate the tough fabric, and it's easy to then count rather more than you expected.
I use short, sharp sewing scissors for , as they have far more control than a knife. However, you may find some bits of reinforcement that need you to go back to the knife.
Here's the finished result.
A modification to the process is to leave the flap of material in place. With this approach you cut around the red line in the x-ray photo above, but you don't count along the upper away from the midsole.
Here you can see the results of this partial "shoe-ectomy". This approach doesn't give quite the same level of freedom as completely removing the flap, but it does have some other advantages. You're less likely to get debris in your shoe when walking, as the flap partly covers the opening (it doesn't help much when slogging your way through long grass or undergrowth.) The flap also tends to keep your toes a tiny bit warmer, which is good in winter, but bad in summer. The main benefit is that you're less likely to get rubbing from the edge of the midsole, which can occasionally be an issue.
Sometimes the edge of the shoe can have a lip that holds the insole in place. This can cause discomfort and blisters, so you may need to remove the lip. Be careful not to cut any of the stitching that holds the shoe together. You can see the stitching fairly clearly on this picture.

5 Modifying for Boggy Ground

Running through boggy ground isn't practical with cut open shoes. The mud gets into the shoe and is hard to remove. The alternative is to cut the shoe, leaving most of the upper in place, then tape over the gaps. I'll add more details and photos as I perfect this technique. I've found the best approach is to use KT Tape glued down with "fantastic elastic" glue. Pair Ups describes the use of KT Tape and glue nicely.

6 Downsides

There are some downsides to cutting open the toe box.

  • You can't return shoes you've cut open. In fact, you can't even give them away!
  • It's rather disconcerting to cut open shoes you've just paid a lot of money for.
  • The shoes can rip open because of the extra stress of the cuts. However, in the thousands of miles I've been running in shoes cut open, I've only had two pairs tear and then only after a lot of miles.
  • You can get debris into the shoe. I've only found this to be an issue when walking, not running unless I'm running through long grass.

7 The De-Snowshoe Modification

There is a tendency for Maximalist shoes to not only have a thicker sole, but to also extend the sole outwards. This means the contact patch of the shoe is much wider than your foot, almost like a snowshoe. This extension can create torsional (twisting) forces on your ankle if your foot lands on the edge first. I've found it's worth trimming away this excess, as shown in the image below. [[File:Clayton200 Snowshoe.jpg|none|thumb|400px|The Hoka Clayton with the sides of the sole trimmed to remove the "snowshoe".]]

8 References

  1. S.A. Mays, Paleopathological study of hallux valgus, American Journal of Physical Anthropology, volume 126, issue 2, 2005, pages 139–149, ISSN 0002-9483, doi 10.1002/ajpa.20114
  2. Michael J. Coughlin, Hallux valgus, Postgraduate Medicine, volume 75, issue 5, 2016, pages 174–187, ISSN 0032-5481, doi 10.1080/00325481.1984.11698000
  3. A M Perera, Lyndon Mason, M M Stephens, The Pathogenesis of Hallux Valgus, The Journal of Bone and Joint Surgery-American Volume, volume 93, issue 17, 2011, pages 1650–1661, ISSN 0021-9355, doi 10.2106/JBJS.H.01630
  4. 4.0 4.1 Fay Crawford, Colin E Thomson, Fay Crawford, Interventions for treating plantar heel pain, 2003, doi 10.1002/14651858.CD000416
  5. 5.0 5.1 P. Caravaggi, T. Pataky, J. Y. Goulermas, R. Savage, R. Crompton, A dynamic model of the windlass mechanism of the foot: evidence for early stance phase preloading of the plantar aponeurosis, Journal of Experimental Biology, volume 212, issue 15, 2009, pages 2491–2499, ISSN 0022-0949, doi 10.1242/jeb.025767
  6. 6.0 6.1 EA Fuller, The windlass mechanism of the foot. A mechanical model to explain pathology, Journal of the American Podiatric Medical Association, volume 90, issue 1, 2000, pages 35–46, ISSN 8750-7315, doi 10.7547/87507315-90-1-35