Thursday, May 19, 2011
Swinging your arm reduces foot impact'
Swinging your arm reduces foot impact
Some random thoughts.
Swinging the arms as you walk reduces the vertical movement of your centre of gravity. So there is less impact on the feet as your feet hit the ground. Just assuming that they swing freely.
But if you apply some force at the top of the swing, then you can add to this effect.
Using a trekking pole allows you to spread any impact, provided your timing and position is right.
As you walk, you have your arms outstretched for a slow beat, but running you bend them up and then out to increase frequency of the pendulum effect ( and resonance).
The arm forced swinging also controls torque and angular momentum, and explains why it is so difficult to have left arm and left leg, which would work just as well for vertical movements.
Though this depends on whether the left foot lands to the left of the right foot. You would expect a running gait to reduce this spread between where the feet land.
Bruce Tullow ( British athlete in the 1960s ?) used to minimise how high his returning foot was, which always seemed strange. But when you walk you don't lift your leg much at all. Again a frequency effect. To speed up the natural swing and reduce the angular inertia, lifting the leg must have benefits.
This all seems difficult to optimise, but evolution seems to have done a good job. The only aids used by man, until recently, are Lycra (potential energy store), soles (ditto), and zimmers/walking sticks (band aids). The newer improvements are wheels, ski sticks and leg breaks [ used for powering batteries, but can be seen as passive breaking, rather than active breaking. I suppose this is just a more active form of a potential energy store]. Four legged animals have known about ski sticks for years. Kangaroos must use potential energy systems surely.
But where are the equivalents of flying fish, gliding squirrels, spider lines, monkey arm swings?
MartinW
Some random thoughts.
Swinging the arms as you walk reduces the vertical movement of your centre of gravity. So there is less impact on the feet as your feet hit the ground. Just assuming that they swing freely.
But if you apply some force at the top of the swing, then you can add to this effect.
Using a trekking pole allows you to spread any impact, provided your timing and position is right.
As you walk, you have your arms outstretched for a slow beat, but running you bend them up and then out to increase frequency of the pendulum effect ( and resonance).
The arm forced swinging also controls torque and angular momentum, and explains why it is so difficult to have left arm and left leg, which would work just as well for vertical movements.
Though this depends on whether the left foot lands to the left of the right foot. You would expect a running gait to reduce this spread between where the feet land.
Bruce Tullow ( British athlete in the 1960s ?) used to minimise how high his returning foot was, which always seemed strange. But when you walk you don't lift your leg much at all. Again a frequency effect. To speed up the natural swing and reduce the angular inertia, lifting the leg must have benefits.
This all seems difficult to optimise, but evolution seems to have done a good job. The only aids used by man, until recently, are Lycra (potential energy store), soles (ditto), and zimmers/walking sticks (band aids). The newer improvements are wheels, ski sticks and leg breaks [ used for powering batteries, but can be seen as passive breaking, rather than active breaking. I suppose this is just a more active form of a potential energy store]. Four legged animals have known about ski sticks for years. Kangaroos must use potential energy systems surely.
But where are the equivalents of flying fish, gliding squirrels, spider lines, monkey arm swings?
MartinW
