The bouncing of body mass during running

Bouncing Ball

MichaelMaggs Edit by Richard Bartz

While I was preparing for my next race, I was researching the theory I have about my stiffer shoes causing issues with my running style. I was finding the shoes meant to help with a flat foot were actually impacting the way I was able to run in a negative manner.

I became very used to the feeling of the arch as it helps to transfer energy in the process of running in my softer shoes and originally in shoes not designed for running. The irony of the situation is that the shoes designed for running for my foot type seem to be the wrong type of shoe to use.

During running the arch has been shown to store and release approximately 17% of the energy created during each impact of the foot (“The spring in the arch of the human foot.” by Ker Et. Al Nature 325: 147-149, 1987). The arch functions much like a spring. That is a very interesting analogy to consider as this could be one additional point of focus for increasing running efficiency.

I have come to conclude that due to the structure of the harder shoe, my arch was no longer able to create the same range of springing motion during running. So far I have had mostly positive experiences with my softer running shoes and my new Vibram fivefingers KSO. I am phasing in the new fivefingers shoe to strengthen my body and train my brain to better manage the flow of energy in a “barefoot” running shoe. For the moment I am using them as a good training tool. During my run yesterday, I ran along a soft beach and got sand in my shoes. This was quite uncomfortable with a sandpaper effect taking place with my feet so I decided to stop running to remove the sand from my shoes.

When a human runs the center of mass of the body has been shown to rise and fall like a bouncing ball. What an interesting way to think of running when it comes to the overall transfer of energy. Within elements like tendons and muscles the bouncing is driven on a system of springs. When the body runs it passively absorbs energy by muscles and tendons in a leg whenever a foot hits the ground and recoils much like a rubber band or a spring. There is some interesting research in this area which I plan to continue to follow but in the very least, I hope this knowledge helps with my further training to optimize the transfer of energy. Depending on how the mass of the body is bounced along must play a role in overall efficiency in running.

The use of this bouncing force for running efficiency seems to be best created with a  quick 180 steps per minute (high cadence turnover) with a very small “bounce” effect to take advantage of the body’s springing systems. Clearly, vertical bouncing is not a good idea here as it would increase unnecessary stress on the body’s joints and waste some energy moving the body’s mass upwards. The focus is in part to keep all energy and alignment in the direction of movement. It seems the ideal may be to be like a skipping rock in a still pool. In addition, finding the perfect alignment so the body’s muscles do not have to do extra work maintaining balance is really helpful in finding the illusive “sweet spot”.

Today, my 10 Mile Easter Road Race on April 2, 2010 went very well. I was able to finish strong, with good form and I did not feel the same issues with my breathing as I did in the Chilly. It felt really good to have a sufficient amount of energy despite having trouble falling asleep the night before.

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    1. [...] up a bit at the 3K mark, but loosened up as I continued along the race. I was able…

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