1. Humans: Walking and Running
Biology 201 Dr. Edwin DeMont
Humans: Walking and Running
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2. A variety of energy saving mechanisms have evolved.
Terrestrial movement
A variety of energy saving mechanisms have evolved.
Legged (2 or 4) terrestrial locomotion is metabolically expensive. (Why?)
Mechanisms are very different, depending on the gait of locomotion.
Human walking and running gaits are very different, and thus save energy in different ways.
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3. Demonstration of walking and running
Human Movement
Demonstration of walking and running
My computer apps on ‘caesar’ (S:) Biomechanics Programs
HBMA5.2 Press Run (Arrow under the Edit near top) Select Image Series Accept Settings Step >
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4. Walking Vertical (and horizontal) changes in center of mass.
Images from The Human Machine, McNeill Alexander.
Filmed live
Vertical (and horizontal) changes in center of mass.
Contact leg is straight.
Mechanical energy of the center of mass changes during cycle.
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5. Center of mass rotates around straight leg.
Walking
Filmed live
Center of mass rotates around straight leg.
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6. Walking
Center of mass and support leg look like an innervated pendulum.
Mechanical energy changes in a pendulum similar to a human walking.
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7. Pendulum Energy of motion is called kinetic energy
units are joules
where m is the mass of the object (kg) and V is the velocity of the object (m/s).
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8. Pendulum
Another type of energy we will examine is the energy of height (or position), and is called potential energy:
P.E. = mgh
units in Joules
where m is the mass of the object (kg), g is the acceleration of gravity, and h is the ‘height’ (m) of the object.
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9. Mechanical energy is conserved in a pendulum.
Online Example
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10. Walking
Total
K.E.
P.E.
Energy 2 3
Time
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11. Mechanical energy of the center of mass changes during cycle.
Running
Filmed live
Large vertical and horizontal oscillations
Knees bent
Aerial phase
Mechanical energy of the center of mass changes during cycle.
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12. Running ?
Energy d b
Time
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13. Running
External mechanical energy is transferred into internal ‘elastic’ energy.
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14. Similar to hopping on a pogo stick.
Running
Similar to hopping on a pogo stick.
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15. ‘Springs’ are achilles tendon and ligaments in the bottom of the foot.
Running
‘Springs’ are achilles tendon and ligaments in the bottom of the foot.
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16. Running
Energy transfer
Energy d b
Time
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