Michael and others:
This is certainly an interesting topic where our language gets
confused with the functional anatomy. Muscles have a large
variety of functions in our everyday behaviours that are
difficult to describe in an anatomical sense. The anatomical term
"knee flexor" is a traditional term that describes the
orientation of the line of action of the muscle tendon. So I am
not sure how you can use the anatomical term "knee extensor" to
describe the orientation of the line of action of the hamstring
tendons?
Muscle function descriptions have been attempted with terms like
stabilizer, synergist, antagonist.... There are many potential functional
reasons why the hamstring muscles are active during knee motion
in the sagittal plane or when there is no motion. However, from a
simplistic point of view, the
hamstrings muscle forces act to accelerate the segment masses in an
angular or linear manner. People often focus on the angular
displacement or linear displacement of the tibia relative to the
femur which is NOT an indication of the direction of the force.
I guess the other manner that the
anatomical terms might be translated into some functional
relevance is to say that a knee flexor would tend to produce
angular acceleration of the tibia relative to the femur such that
the rate of knee extension would tend to decrease or the rate of
knee flexion would increase.
I look forward to hearing if the hamstrings can produce a torque
about the knee joint that would tend to increase the rate of knee
extension or decrease the rate of knee flexion.
Murray
>
>
>
> so, I will throw out a concept many will think is ludicrous, others
> thinking is obvious
>
>
> What is the second major extensor of the knee in a close chain reaction?
>
>
>
> Hamstrings. Why else do long distance runners develop short hams?
> Wolfe (sp?) said it all: form follows function
> It is an extensor, man!----both the hip and the knee, in a closed
> kinetic chain
>
>
> Comments, please
>
> maybe this will be the next "Pilates" discussion.
>
> Michael Ritchie
> Halifax, Nova Scotia, Canada
>
>
--
________________________________________________________________
Murray Maitland PhD PT
Associate Professor and Physical Therapist
Faculty of Kinesiology
Sport Medicine Centre
University of Calgary
2500 University Drive NW
Calgary, Alberta
T2N 1N4
(403) 220-8943 office
(403) 220-8232 clinic
(403) 282-6170 fax
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