20th Jan2012

The Case For Minimalist Shoes in Fitness Training

by Tom

“The human foot is a masterpiece of engineering and a work of art.” – Leonardo DaVinci

As is evident from his sketches of vitruvian man, Leonardo DaVinci had a strong affinity for the measurements and function of the human body. He was also a very accomplished mechanical engineer and architect, among other things. Given his genius and his legacy of great works, his quotation about the human foot should be taken into deep consideration.

The Power of the Arch

The key to quality architecture and engineering is a design that will bear load and distribute force in the best way possible. One of the simplest and widely used structures is the arch. The arch, notably used in bridge design, is able to reduce shear, tension, and torsional stress by taking advantage of the compressive force on the arch and making the whole structure more stable horizontally. Though the first arch bridge dates back to 1300 B.C., they weren’t used extensively until the Romans utilized them in structures such as the Segovia Aqueduct (A.D. 100). Below is a basic illustration of an arch bridge:

 

In an arch bridge, the keystone bears the brunt of the force from the mass above it. Force is transferred horizontally along the components of the arch all the way to the supporting abutments, which are positioned securely on the ground. As long as the abutments are securely positioned, the whole structure will be rock solid. The more compressive force that’s placed on the keystone, the stronger the arch becomes. Many arch bridges are constructed using a heavy fill material to increase the weight on top of the keystone in order to make the arch more stable and resistant to shear and torsion.

The Rainbow Bridge near Niagara Falls is a more modern steel version of the arch bridges originally popularized by the Romans. Unlike Roman concrete architecture that utilized many rows and sometimes multiple columns of arches for a single bridge, steel architecture allows for a long single span to be covered with one arch.

Arches of the Foot

By now, almost everyone has heard about arches in relation to the foot. Whether you’re talking about arch support or flat feet, the concept of the arch is widely known. What you may not know is that the foot has three distinct arches, which are shown below.

One of the reasons Da Vinci was so mesmerized by the human foot is because our foot arches work much the same magic as arches do in bridge construction. While it’s phenomenal that we can exert hundreds (or even thousands) of pounds of compressive force on a foot that has a relatively small surface area, it becomes more understandable after learning about arches. Similar to a Roman concrete bridge, our arches also have keystones, only instead they are made up of bone.

 

Refer to the picture above to locate the keystones for each arch. In the anterior transverse arch, the keystone is the intermediate cuneiform. In the lateral longitudinal and medial longitudinal arches, the keystones are the cuboid and talus, respectively. As these keystone bones are compressed during everyday activity and exercise, the vertical compressive force is transferred horizontally along the arches and is distributed to the ground. Just like a bridge arch, compressive force on the keystone bones will help to reduce shear and torsion forces on the whole structure (the foot and ankle).

Cushioned Soles

Knowing what you now know about arches, go back up to the diagram of the arch at the top of the post and imagine each abutment is resting on top of a Godzilla sized air mattress. That is a surefire way to take an ingeniously designed support structure and render it immediately unstable. The second you place an arch on a giant marshmallow (running shoes), the stability and strength is severely compromised.

Your response might be that cushioned heels allow us to run on pavement without as much jarring force as we would experience barefoot or in flats. Actually, the opposite is true. When you run in cushioned running shoes, heel striking becomes the norm since there is no pain associated with it due to the shoes. However, this is not the natural way we were designed to run and use our foot arches. The results of this Harvard study show a significantly steeper acceleration of impact force from heel striking than from striking with the mid or forefoot. There’s no question that heel striking is the wrong way to run and puts a great deal of stress on ankles, shins, and knees. If you have any doubts, do a little experiment. Take your shoes off and gently run in place on a hardwood floor. Without thinking, you’ll immediately start landing softly on the mid and forefoot, taking advantage of your arches. You’ll have to force yourself to land on your heels, which will be a much more uncomfortable experience.

Arch Support

Now let’s consider arch supports. First off, realize that there isn’t a single arch structure in the world that requires support. The arch derives its strength from the fact that it is unsupported by scaffolding and can compress and become more stable. Now also consider that we are not made of lifeless stone, but of living tissue that must grow and be used constantly in order to remain strong. If you or anyone you know has ever broken a bone, you probably have some experience with joint or limb support, also known as a cast or a brace. What happens after wearing one of these for a while? Muscle, soft tissue, and bone atrophies to the point that it is noticeably weaker and smaller than the unbraced limb. If you have fancy shoes with arch support or custom orthotics, you’re effectively casting your feet every single day. It’s no surprise that there is such an abundance of foot problems in our society today. Our species has thrived for millions of years without the need for constant artificial support in any part of our body.

Performance and Health = Uninhibited Ground Contact

You might be wearing cushioned shoes because ‘that’s what everyone does’ and ‘you’ve done it forever’. You may also think (thanks in no small part to the brilliance of marketing) that all of the professional and elite runners wear cushioned shoes. Would it surprise to you to find out that hardly a single thing has changed in performance shoe design over the past 75 years? Below is the Adidas shoe that Emil Zatopek used to win the 5,000 and 10,000 meter races in the 1952 Olympics. The second picture is the most recent performance track flat designed by Nike for professional track athletes.

Other than the price, the marketing, and the color scheme, nothing has changed. The reason for this is the simple fact that effective and high performance running is done best when there is as little material between foot and ground as possible. Going back to the arch, this makes complete sense. If you consider that the bones and muscle fascia at the ends of the foot act similar to abutments in an arch, the most strength, power, and stability will be derived from having those abutments connected to the ground with as little interference as possible. This is why powerlifters typically deadlift in ballet slippers and gymnasts perform barefoot.

While cushioned shoes will certainly inhibit running performance and expression of strength in the gym, the main problems with them is that they promote poor running mechanics and don’t allow the feet to strengthen in a natural way. First off, the vast majority of people run incorrectly already due to these shoes. And even for those that do run with a correct midfoot strike, it’s very easy to get lazy with cushioned soles and fall into heel striking. It’s like using the bumper lanes at the bowling alley. You may be knocking pins down and having fun, but you’re still doing things the wrong way and using an artificial crutch.

Transitioning to Minimalist Shoes

In order to learn how to run correctly and get the most out of lifting in the gym, you’ll be best served by finding a pair of minimalist shoes and getting used to them. While Vibram Five Fingers are all the rage right now, I found them difficult to get in and out of as well as impractical and smelly since you can’t wear regular socks with them. My number 1 recommendation would be the New Balance Minimus trail shoe. They have a nice wide forefoot to allow you to spread the toes, can be worn with our without socks, are incredibly sturdy, and have just enough cushion in the small heel nubs to make the transition from cushioned shoes fairly painless. I’m going to do a full review of them soon on the blog.

Beyond the Minimus, the Merrell Trail Glove, Vivobarefoot Evo, and Innov8 Bare-XF are really good options.¬†When switching, take it slow and let your ankles, feet, and Achilles and other soft tissue adapt. Try running on grass or a track for a while and really be conscious of midfoot striking. You’ll probably notice that your strides will get shorter and you’ll feel like you’re gliding in a straight line like on a conveyor belt rather than in a jerky up and down sort of way. Eventually, it’s even fun to experiment running on grass barefoot. Not only will this improve your stride, but tactile contact between your feet and the ground will enhance your stability and coordination.

18th Jan2012

DIY Tire Sled

by Tom

If you have some space in or around your gym like we do here at Fort Mason, a sled can be a very valuable conditioning tool as part of circuits or as a nice finisher to a weight training session. If you have some cash lying around, I’d recommend the versatile¬†prowler from Elite FTS or the affordable power sled from Muscle Driver. Since I eventually want two (or even three) sleds in order to accommodate larger groups and keep rest time shorter, I decided to make one on my own to keep the cost down. Here is the material list and how I went about building it.

Materials

I picked up a couple of tires at the local Pick N Pull. For a used tire with a 13-14 inch hole sold as a single, you shouldn’t have to pay more than $16 for each one. Regardless of how big the tire itself is, I’d recommend sticking with one that has less than a 15 inch hole. In order to add weight to the tire later, we’re going to drop standard 45lb or bumper plates into the tire and you want them to rest securely in there. Plates are about 17 inches wide, so if you buy a large tire with a 17 inch hole, the plate will just fall through and drag on the ground. Not good.

When looking through the tires, try to find one with very hard, sturdy tread. If the tread is bald or thin, it will provide a less stable base to secure the handle and tow rope. The sturdier the tread, the longer the rubber will hold out after being pulled on hundreds of times. I bought Michelin X Radials, which have a long tread life compared to most other tires.

These are all the necessary materials and cost of each

  • 14 inch used Michelin X Radial Tire – Pick N Pull $16.00
  • Power drill with a phillips head bit
  • Door pull handle with 4 screw anchor points – Home Depot $3.70
  • Length of 2×4 just long enough to accommodate pull handle
  • 4 count of 1.5 inch wood screws
  • 15 foot emergency car tow strap – Home Depot $16.50
  • Total Cost = $36.20

I could have cut down on the cost quite a bit by trying to find a cheap or even free strap, but the car tow strap was too cool to pass up. The locking hooks are heavily stitched into either side of the strap, the material is wide and comfortable for pulling, and the strap and hooks are rated for up to 5000 pounds.

Attaching the Pull Handle

I first considered attaching the pull handle directly to the tire using bolts, nuts, and washers. After thinking about the force that would be generated and the possibility of ripping the rubber, I settled on anchoring it to a 2×4 backing using wood screws. Since the 4 anchor screws are all essentially connected via the 2×4, there is a whole lot more stability. The hardest part is getting in the first screw. Place the handle lengthwise in the center of the tire like the picture above and get the first screw through the tire rubber. Then reach in with the 2×4 and go by feel where the screw should connect to the wood. Then drill in while pressing hard on the wood. Once the first screw is securely in, the other three are pretty easy.

Adding Weight

In order to add weight to the sled, you need to increase the diameter of the top of the tire to accommodate bumper plates. First, start by centering a bumper plate on top of the tire as shown below.

Make small pencil or chalk marks around the plate so you know how wide of a space you need to cut in order to make the plate fit. Stay about a quarter to a half inch outside these marks while you cut. To do the cutting, the best method is probably to use a drill to make a small hole then use a handheld jigsaw to make the cut all the way around the tire. I didn’t have a jigsaw, so I just used the blade on my leatherman skeletool, which did the job very quickly. Any serrated hunting knife will work just fine. After you’re done, there will be enough space to drop in plates.

My cut was by no means perfect, but going a little wider than necessary certainly won’t hurt you. It will give you a little more margin to set plates in there on top of each other. In hindsight, I’m going to do the cutting before attaching the pull handle the next time I make one of these. You can see in the picture above that the 2×4 anchor is much more visible and accessible after making the cut. Getting the first screw attached to the 2×4 would be much easier at this point than prior to the cut.

The Finishing Touches

Next, just attach the two tow rope hooks to the pull handle and you’re good to go. Here is the final product. It’s definitely a versatile and quality piece considering it only cost $35 to make. After a first test of a total of 50 sprints on blacktop, there is no visible wear on the bottom tread and the pull handle is just as secure as when it was built.

 

Use

The tire itself weighs a little over 20 pounds, so using it with a 25 pound plate turns it into a 50 pound sled. This was more than enough weight to gas us on repeats of 40yd sprints followed by a 40yd backwards pull to the starting line. If you wanted to load it up, the tire could probably hold about 4 45lb plates, making it a 200lb sled. Since the friction of the tire on asphalt is pretty substantial, there would probably never be a need for more than that. While the loop works well as a harness, you could easily detach one of the rope hooks and clip it to a standalone shoulder harness, which would allow the arms more freedom during sprinting. Another really cool use would be to take a cable rope or lat pulldown bar and clip it to one of the rope hooks to do straight arm overhead pulls of the sled. There would be less speed to it, but it would tax the entire body similar to a car push.

There are also other potential great uses like using it for hand over hand pulls if I attach it to a long manila rope. It could also easily be converted for farmer’s walks by detaching the tow rope and carrying it by the handle. Regardless of how you use it, it’s definitely a great addition to any gym with outdoor space.