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John Martinson
11-16-1992, 05:40 AM
Subject: Horizontal and Vertical components of knee extension

A fortuitous meeting with Prof. George Twardokens (Kinesiology specialist
here at Univ. of Nevada, Reno) a number of years ago eventually led to the
development of a lab bench device for human power output in an oscillating
linear motion in contrast to the crank arms of bicycles and some wheelchairs.
But a related question raised at that time remains unanswered in my mind
and I would welcome references or authors' names from BIOMCH folks. The
question has to do with the horizontal component of leg extension. We tried
a small research effort in a PE class once on this and mostly learned that
we needed more sophisticated research tools. But that was before the
widespread use of videography and computer graphics so by now someone else
may have attacked the problem in a better way. Since I can't draw pictures
here, please be patient with the following verbal description.

Many studies have been done on the vertical or lifting force of a standing
person at various angles at the knee between the femur and the tibia. But
in going from a flexed to a fully upright position imagine that the back
of the knee is contact with a dynamometer so that the (nearly) horizontal
movement of the knee exerts a force "backwards" or horizontally. Now
imagine that this force is precisely recorded at various angles of knee
extension simultaneously with the vertical or lifting component. Then we
would like to plot the relationship of these two forces during a full range
of movement from deep knee bend to fully extended leg. At the same time it
would be nice to do electro-myography on the quadriceps to correlate
muscle action through this range of movement.

I would delight in learning that this has been done, or being directed
toward investigators likely to have considered this question.

My expectation would be that beyond an angle of 150 degrees or so, very
small changes in the horizontal component force would be correlated with
increasingly large changes in the vertical component. But what kind of
increments and what kinds of forces? We found, for instance, that a
conventional goniometer was inadequate when trying to measure small
angular changes as the subjects got closer and closer to full extension.
Insights on this would be very useful in the design of linear power
devices.

I also suspect that precise measurements very close to full extension
might help resolve the seemingly interminable debates about the origins,
advantages, disadvantages of hominid bipedalism among physical anthropologists.
In general, the occasional bipedalism of the other primates does not involve
the full extension of big toe, ankle and knee of humans (consider the ballerina
up "on point"). But what kinds of mechanical advantages or energy efficiencies
might we humans enjoy because of this? Your suggestions are invited.

Incidentally, skiing biomechanicians might be interested to know that Prof.
Twardokens' magnum opus "Universal Ski Techniques" has been published. In
addition to its coverage of skiing History, Techniques and Teaching Methods,
its coverage of the biomechanics of downhill skiing is probably the most
comprehensive to be found in any single volume on skiing.

John Martinson
Facilities Services (114)
Univ. of Nevada, Reno
Reno NV 89557

>From marty Sun Nov 15 19:30:27 1992
From: marty
To: BIOMCH-L@HEARN.nic.SURFnet.ul
Subject: Horizontal and Vertical components of knee extension
Date: Sun, 15 Nov 1992 19:30:27 GMT

A fortuitous meeting with Prof. George Twardokens (Kinesiology specialist
here at Univ. of Nevada, Reno) a number of years ago eventually led to the
development of a lab bench device for human power output in an oscillating
linear motion in contrast to the crank arms of bicycles and some wheelchairs.
But a related question raised at that time remains unanswered in my mind
and I would welcome references or authors' names from BIOMCH folks. The
question has to do with the horizontal component of leg extension. We tried
a small research effort in a PE class once on this and mostly learned that
we needed more sophisticated research tools. But that was before the
widespread use of videography and computer graphics so by now someone else
may have attacked the problem in a better way. Since I can't draw pictures
here, please be patient with the following verbal description.

Many studies have been done on the vertical or lifting force of a standing
person at various angles at the knee between the femur and the tibia. But
in going from a flexed to a fully upright position imagine that the back
of the knee is contact with a dynamometer so that the (nearly) horizontal
movement of the knee exerts a force "backwards" or horizontally. Now
imagine that this force is precisely recorded at various angles of knee
extension simultaneously with the vertical or lifting component. Then we
would like to plot the relationship of these two forces during a full range
of movement from deep knee bend to fully extended leg. At the same time it
would be nice to do electro-myography on the quadriceps to correlate
muscle action through this range of movement.

I would delight in learning that this has been done, or being directed
toward investigators likely to have considered this question.

My expectation would be that beyond an angle of 150 degrees or so, very
small changes in the horizontal component force would be correlated with
increasingly large changes in the vertical component. But what kind of
increments and what kinds of forces? We found, for instance, that a
conventional goniometer was inadequate when trying to measure small
angular changes as the subjects got closer and closer to full extension.
Insights on this would be very useful in the design of linear power
devices.

I also suspect that precise measurements very close to full extension
might help resolve the seemingly interminable debates about the origins,
advantages, disadvantages of hominid bipedalism among physical anthropologists.
In general, the occasional bipedalism of the other primates does not involve
the full extension of big toe, ankle and knee of humans (consider the ballerina
up "on point"). But what kinds of mechanical advantages or energy efficiencies
might we humans enjoy because of this? Your suggestions are invited.

Incidentally, skiing biomechanicians might be interested to know that Prof.
Twardokens' magnum opus "Universal Ski Techniques" has been published. In
addition to its coverage of skiing History, Techniques and Teaching Methods,
its coverage of the biomechanics of downhill skiing is probably the most
comprehensive to be found in any single volume on skiing.

John Martinson
Facilities Services (114)
Univ. of Nevada, Reno
Reno NV 89557

>From marty Mon Nov 16 11:19:56 1992
From: marty
To: BIOMCH-L@HEARN.bitnet
Subject: Vertical & horizontal components of leg extension
Date: Mon, 16 Nov 1992 11:19:56 GMT

Subject: Horizontal and Vertical components of knee extension

A fortuitous meeting with Prof. George Twardokens (Kinesiology specialist
here at Univ. of Nevada, Reno) a number of years ago eventually led to the
development of a lab bench device for human power output in an oscillating
linear motion in contrast to the crank arms of bicycles and some wheelchairs.
But a related question raised at that time remains unanswered in my mind
and I would welcome references or authors' names from BIOMCH folks. The
question has to do with the horizontal component of leg extension. We tried
a small research effort in a PE class once on this and mostly learned that
we needed more sophisticated research tools. But that was before the
widespread use of videography and computer graphics so by now someone else
may have attacked the problem in a better way. Since I can't draw pictures
here, please be patient with the following verbal description.

Many studies have been done on the vertical or lifting force of a standing
person at various angles at the knee between the femur and the tibia. But
in going from a flexed to a fully upright position imagine that the back
of the knee is contact with a dynamometer so that the (nearly) horizontal
movement of the knee exerts a force "backwards" or horizontally. Now
imagine that this force is precisely recorded at various angles of knee
extension simultaneously with the vertical or lifting component. Then we
would like to plot the relationship of these two forces during a full range
of movement from deep knee bend to fully extended leg. At the same time it
would be nice to do electro-myography on the quadriceps to correlate
muscle action through this range of movement.

I would delight in learning that this has been done, or being directed
toward investigators likely to have considered this question.

My expectation would be that beyond an angle of 150 degrees or so, very
small changes in the horizontal component force would be correlated with
increasingly large changes in the vertical component. But what kind of
increments and what kinds of forces? We found, for instance, that a
conventional goniometer was inadequate when trying to measure small
angular changes as the subjects got closer and closer to full extension.
Insights on this would be very useful in the design of linear power
devices.

I also suspect that precise measurements very close to full extension
might help resolve the seemingly interminable debates about the origins,
advantages, disadvantages of hominid bipedalism among physical anthropologists.
In general, the occasional bipedalism of the other primates does not involve
the full extension of big toe, ankle and knee of humans (consider the ballerina
up "on point"). But what kinds of mechanical advantages or energy efficiencies
might we humans enjoy because of this? Your suggestions are invited.

Incidentally, skiing biomechanicians might be interested to know that Prof.
Twardokens' magnum opus "Universal Ski Techniques" has been published. In
addition to its coverage of skiing History, Techniques and Teaching Methods,
its coverage of the biomechanics of downhill skiing is probably the most
comprehensive to be found in any single volume on skiing.

John Martinson
Facilities Services (114)
Univ. of Nevada, Reno
Reno NV 89557

>From marty Sun Nov 15 19:30:27 1992
From: marty
To: BIOMCH-L@HEARN.nic.SURFnet.ul
Subject: Horizontal and Vertical components of knee extension
Date: Sun, 15 Nov 1992 19:30:27 GMT

A fortuitous meeting with Prof. George Twardokens (Kinesiology specialist
here at Univ. of Nevada, Reno) a number of years ago eventually led to the
development of a lab bench device for human power output in an oscillating
linear motion in contrast to the crank arms of bicycles and some wheelchairs.
But a related question raised at that time remains unanswered in my mind
and I would welcome references or authors' names from BIOMCH folks. The
question has to do with the horizontal component of leg extension. We tried
a small research effort in a PE class once on this and mostly learned that
we needed more sophisticated research tools. But that was before the
widespread use of videography and computer graphics so by now someone else
may have attacked the problem in a better way. Since I can't draw pictures
here, please be patient with the following verbal description.

Many studies have been done on the vertical or lifting force of a standing
person at various angles at the knee between the femur and the tibia. But
in going from a flexed to a fully upright position imagine that the back
of the knee is contact with a dynamometer so that the (nearly) horizontal
movement of the knee exerts a force "backwards" or horizontally. Now
imagine that this force is precisely recorded at various angles of knee
extension simultaneously with the vertical or lifting component. Then we
would like to plot the relationship of these two forces during a full range
of movement from deep knee bend to fully extended leg. At the same time it
would be nice to do electro-myography on the quadriceps to correlate
muscle action through this range of movement.

I would delight in learning that this has been done, or being directed
toward investigators likely to have considered this question.

My expectation would be that beyond an angle of 150 degrees or so, very
small changes in the horizontal component force would be correlated with
increasingly large changes in the vertical component. But what kind of
increments and what kinds of forces? We found, for instance, that a
conventional goniometer was inadequate when trying to measure small
angular changes as the subjects got closer and closer to full extension.
Insights on this would be very useful in the design of linear power
devices.

I also suspect that precise measurements very close to full extension
might help resolve the seemingly interminable debates about the origins,
advantages, disadvantages of hominid bipedalism among physical anthropologists.
In general, the occasional bipedalism of the other primates does not involve
the full extension of big toe, ankle and knee of humans (consider the ballerina
up "on point", but let's not get into discussion of "plantar flexion"
here). But what kinds of mechanical advantages or energy efficiencies
might we humans enjoy because of this? Your suggestions are invited.

Incidentally, skiing biomechanicians might be interested to know that Prof.
Twardokens' magnum opus "Universal Ski Techniques" has been published. In
addition to its coverage of skiing History, Techniques and Teaching Methods,
its coverage of the biomechanics of downhill skiing is probably the most
comprehensive to be found in any single volume on skiing.

John Martinson
Facilities Services (114)
Univ. of Nevada, Reno
Reno NV 89557