Kevin, Bruce, Howard,
I see what you are saying. I am not convinced if the change in stride
length is coming from a prolonged midstance or a prolonged propulsion. I
know Bruce or Howard know the answer. I hope one can answer this.
Sincerely,
Stanley
At 09:59 PM 12/5/04 -0800, you wrote:
>Stanley and Colleagues:
>
>Stanley wrote:
>
><<I understand the part about the forefoot valgus post preventing lateral
>instability and narrowing the base of gait.
>
>But I am confused regarding stride length. Does the forefoot valgus wedge
>pronate the subtalar joint so the stance phase muscles have to fire longer,
>and the midtarsal joint is unlocked to increase the range of motion and
>allow the leg to go further forward prior to heel off; or is it that the
>longer duration of the firing of the gastrocnemius allows for a greater
>propulsion so the body is airborne longer, and therefore longer stride
>length?>>
>
>I believe that the longer duration of firing of the gastrocnemius-soleus
>complex will allow for a longer stride length since the stance phase limb
>shows a longer propulsion period and therefore is able to push the body
>farther forward before the swing phase limb contacts the ground.
>
>To feel the opposite effect, of stride shortening, just place a piece of
>1/4" adhesive felt plantar to your first metatarsal head of both feet and
>measure your stride length (e.g. take length of ten consecutive
>strides). Then compare this to placing a 1/8" piece of adhesive felt
>plantar to your 4th and 5th metatarsal heads to see how it affects your
>stride length.
>
>Interesting phenomenon.
>
>Cheers,
>
>Kevin
>
>****************************************************************************
>Kevin A. Kirby, DPM
>Adjunct Associate Professor
>Department of Applied Biomechanics
>California School of Podiatric Medicine at Samuel Merritt College
>
>Private Practice:
>107 Scripps Drive, Suite 200
>Sacramento, CA 95825 USA
>
>Voice: (916) 925-8111 Fax: (916) 925-8136
>****************************************************************************
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