Saturday, September 20, 2014

9/21/14: 1792.1 to 1802.9 miles: How fast are your feet?

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Virtual Hike
Animated Street View - leg 1
Animated Street View - leg 2
(Entering Washington State)
The second leg today entered the state of Washington. Leaving one state and entering another always gives me a sense of accomplishment tinged with regret for leaving the previous state behind. 

The left coast of the country is filled in. Soon, I'll start the race across the top of the country. For now, I need to focus one day at a time in Washington

I took my long walk before sunrise. Today is the first day of fall and it seemed fitting to take a picture of a tree whose leaves have completely changed. True, it's hard to see in the dark, but that's reality.

It rained lightly about an hour before my walk which accentuated all the fragrances. When will they have scratch and sniff for blogs?

Foot Speed

Have you ever stubbed a toe? Did you ever stop to consider why it hurt so much? 

The topic of today's post is foot speed which turns out to be a word problem for those few who like word problems.

The foot is faster than the mind can consciously think, To walk efficiently, the road walker must turn the walking over to the subconscious mind.
If I told you one of my feet was ticketed in a school zone, would you believe me?

I wouldn't believe me either, but if a person is walking at four miles per hour, the maximum speed of their feet is about 25 mph. 

Maybe I should have kept the suspense going, but the calculations that follow are for the math and physics minded. 

Time in Air
The foot is only moving forward when it is in the air.

While walking, there is a point when both feet are on the ground. This means the feet must be on the ground more than 50% of the time.

I read an old study that shows the foot is on the ground 62% of the time and airborne 38% of the time. 

"This is why I rode a bicycle."

For physics majors 
(Note: The foot only moves forward while airborne.)
Average Velocity = distance/time
Average Velocity = 4 miles/0.32 hours
Average Velocity = 12.5 mph

If we think of the leg as a pendulum, it decelerates to a stop at both ends of the swing and is at maximum velocity at the bottom.

As an estimate, the speed at the bottom is twice the average speed.

Therefore, the maximum velocity of the foot while walking 4 mph is approximately 25 mph.

Now you know why it hurts so much to stub your toe. Ouch!

I made a video that shows how quickly everything happens. It's not scientifically accurate, but it's good enough. This is for those who prefer visual presentations without all the physics.

Walking is a precision sport

People don't think of walking as taking skill because they walk all the time. As the walking speed increases, the tolerances become tighter. When I learn more about these, I'll post what I learn.

For now, I'll say that increasing walking speed takes many miles of practice and if it's done too quickly, there are dangers of injuries. The mind as well as the muscles need to change.

In the next post, I'll reveal my lunar training plan that will speed training while walking fewer miles.

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