Tuesday, March 9, 2010

Running in Minimal Shoes

A large following and interest in barefoot running has been developed lately, encouraged by Christopher McDougall's book "Born to Run" which describes the Tarahumara or RarĂ¡muri, an indigenous peoples from Northern Mexico, who have been known to run long distances in thin soled sandals. We recently assisted a runner with some video analysis as he trains to run a marathon wearing the Vibram FiveFingers minimal shoe.

Last year we discussed using video analysis to analyze rear foot pronation and attempted to see whether there was a difference in rear foot pronation between running in shoes and running barefoot. We described how a camera should be setup and the measurements that could be done. However, as we studied a runner who does not suffer from pronation we were only able to see a normal amount of pronation in the foot stance phase of his running.

Our runnerwanted to determine how much he was pronating when running in his FiveFingers minimal shoes. He also reported getting blisters under the pads of his feet and on his right big toe.

He used all the techniques for filming his motion that we have discussed on this website in the past and sent the videos on to us. He set up to run on a treadmill at a constant speed of 8.3 miles per hour and ran 12 miles in total capturing video at intervals along the way. Set his camera on a tripod at the level of the treadmill to capture the video and his foot placement. He captured video both from the side view and the rear view so that we could assist him in analyzing his foot strike. Take a look at the video below.

From the video we have taken a few snapshots to help us analyze his foot strike characteristics.

In the images above we can see a side view of the left and right foot strike. We can see that:
  • Both the left and right foot is inverted at foot strike. This means the feet are turned in and the athlete lands on the outside of his foot.
  • The main muscle used to invert the foot is the Tibialis Anterior (the muscle on the outside of the shin bone). These muscles are also used to dorsi-flex the foot (lift the foot up). This can be seen in the video as the foot and toes are flexed back just before foot strike.
  • Striking with an inverted foot can create a slapping of the foot onto the ground rather than a controlled foot placement.
  • Striking with an inverted foot can also exaggerate any rear foot pronation.
  • The foot strike is occurring toward the midfoot and not the heel. This is to be expected when running in minimal shoes. The runner in minimal shoes is trying to avoid heel impact and is taking greater care to control his foot strike.
Now we can look at his rear foot pronation. In this instance an estimate was made for rear foot pronation using a 4 point angle. Rearfoot pronation is measured as the amount of eversion (rotation inward) of the foot from heel strike through mid stance. The angle is measured by drawing a line along the center of the Tibia bone in the lower leg and another line describing the center line of the Calcaneus (heel bone).

As our runner was concerned that he was pronating more in his right foot, we have looked only at his right foot here:
  • The pronation angles displayed in the images above are estimates. As there are no markers identifying the necessary landmarks of the midline of the Tibia and the midline of the Calcaneus.
  • The athlete lands with an inverted foot position. The rear foot pronation angle of 171 degrees shows this. An angle of 180 degrees would be neutral while anything over 180 degrees is everted (pronated).
  • At mid stance the athlete has 13 degrees of pronation (193-180). The foot is expected to evert (pronate) by approximately 10 degrees through mid stance for normal pronation. Therefore this would be considered excessive pronation.
  • The eversion of the foot from foot strike to midstance is also rapid and large, pronating 22 degrees.
As can be seen from the video and the images our runner pronates while running at 8.3 miles per hour.

Our runner has been training in his Vibram FiveFingers shoes for less than 2 months. Prior to running in these minimal shoes he ran in a shoe offering maximum pronation support. It may therefore be too early to tell whether the minimal shoes are improving his pronation by encouraging him to control his foot placement.

Our runner has also been suffering from blisters, since wearing these shoes. Unfortunately a minimal shoe such as this will likely cause the foot to blister more readily. The shoes are worn without socks (as each toe is separated in the shoe)causing more friction between the shoe and the foot. Being that there is not much cushioning between the shoe and the road surface, any scraping on the hard road or treadmill surface will also cause friction and possible blisters.

It is possible that our runner is in fact suffering from the effects of his blisters and is running as seen in the video because of the blisters on his foot. The exaggerated inverted foot at foot strike may be a way of attempting to protect his foot from injury and further blisters.

We still believe that barefoot running or running in minimal shoes will help to improve a runners mechanics. Barefoot Ken Bob Saxton says, “Don’t strike the ground. If you do it’ll strike back!” The idea of running barefoot or running in a minimal shoe is to feel your feet and understand how much they can take and to learn how to control your running so that you can continue running faster and with less injury.

If you want to try running in minimal shoes, allow yourself sufficient time to get accustomed to running in them before trying to do to long a distance at too high a speed.

Also pull out your video camera and film yourself. This will help you to visualize what you are doing and possibly help you to achieve success in a minimal shoe. We are always ready to offer our services to help you analyze your motion.

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