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    I am working on this Biomechanics assignment given to me from my
    biomechanics professor as part of my final project for the course. And I
    am having a little trouble with some of the calculations.

    Anyway, the assignment is this. We (the class) were each given the same
    standardized hypothetical lizard model. And my specific part of this
    model is to vary the rate of muscle contraction (muscle shortening) on
    this lizard to see how it would affect the following:

    (1) velocity of locomotion (speed),
    (2) stride length (length of a stride for one leg - foot down to foot
    down for same foot)
    (3) stride frequency (rate at which feet are moving - number of strides
    per second)
    (4) power.

    I have calculated the distance the muscle shortens (the muscle in
    question is the caudofemoralis muscle which connects to the femur), but
    now I am having trouble calculating the rate at which this muscle
    contracts. I was wondering if you could look at the model, which is
    typed down at the end of this e-mail and possibly give some ideas on how
    to calculate standard speed on muscle contraction. Thanks!

    * * * *

    Calculations that I made:

    I figured out that the length of muscle contraction for this muscle
    (caudofemoralis muscle) is 15.3 mm. I also figured
    out that the femoral contribution to a step (foot down to foot up), not
    a stride (which is foot down to foot down) is 6.93 cm. Does this make
    any sense?

    * * * *

    Standardized Lizard Model

    Mass = 700 grams
    SVL (snout vent length - measured from snout to anal pore) = 280 mm
    femur length = 45 mm
    tibia length = 45 mm
    limb mass = 1

    Vo (initial velocity) = 157cm/sec = 5.6SVL/sec
    SLo (initial stride length) = 27.5cm/stride
    SFo (initial stride frequency) = 5.7 stride/sec
    DFo (duft factor - amount of stride which foot is on ground) = 40% of

    Io (initial insertion site of caudofemoralis muscle) = 10 mm
    Lo (initial resting length of muscle fibres) = 5 mm
    Lmin (final contracted length of muscle fibres) = 0.5 of Lo
    Ao (initial muscle fiber pinnation angle) = 45 degrees
    N (initial number of muscle fibres) = 10,000
    Fmax (maximum force of caudofemoralis) = 100 newtons
    Fo (initial muscle force) = 0.4 of Fmax
    Vfmax = maximum contraction velocity of muscle fibres
    Vfi (initial contraction velocity of muscle fibres) = 0.5 of Vfmax

    * * * * *

    Thank you so much for atleast trying! I really appreciate it!

    -mary alice allen

    I used to be a SuperHero.....



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