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sigward21
06-08-2004, 05:31 AM
This is in response to Dr. Hinrichs question about gastrocnemius muscle
discomfort during the "Sit & Reach" movement.

I would suggest that as the length of your gastroc does not change with hip
flexion and you are keeping your ankle fixed in neutral (or greater
dorsiflexion than the other position) the structure that you are stretching
(or feeling discomfort in) has to be one that crosses all three joints.

Perhaps it can be attributed to neural tension of the sciatic nerve. It
originates in the lumbosacral spine, so hip flexion would pull it taught at
its proximal end, knee extension would keep it in tension across the back of
your knee and dorsiflexion would pull the terminal branches of its tibial
division (medial and lateral plantar nerves) around the ankle.

To test this hypothesis, assume the position of knee extension, and hip
relatively extended, let your foot hang slightly plantarflexed and then
maximally invert it. You should feel little to no stretch on the lateral
side of your lower leg. Now maintain that inverted position and flex your
hip (as if you were to do a sit and reach test). If you feel a stretch on
the lateral side of your leg and top of your foot then you are likely
putting tension on the fibular (peroneal) branch of your sciatic nerve
resulting in a stretching sensation.

Susan

Susan Sigward PhD PT ATC
University of Southern California
Department of Biokinesiology and Physical Therapy Musculoskeletal
Biomechanics Research Laboratory 1540 East Alcazar st, G-9 Los Angeles, CA
90089-9006
Lab: 323-442-2948
Fax: 323-442-1515
sigward@usc.edu
www.usc.edu/go/mbrl


-----Original Message-----
From: Biomechanics and Movement Science listserver
[mailto:BIOMCH-L@NIC.SURFNET.NL] On Behalf Of Richard Hinrichs
Sent: Sunday, June 06, 2004 4:27 PM
To: BIOMCH-L@NIC.SURFNET.NL
Subject: [BIOMCH-L] Hamstrings and Gastrocs link

Dear fellow biomechanists,

It has been sometime since I have posted a question or comment on this forum
although I still read what the rest of you are writing each day. The
following question comes from observation of my own muscles during
stretching exercises and my own knowledge of anatomy (or perhaps lack
thereof):

Why do I feel discomfort in my gastrocnemius muscles when I attempt a "sit
and reach" (hamstrings) stretch with my ankles in a neutral position vs.
when I do the same stretch with my ankles slightly planter flexed (no
gastrocs discomfort)? This implies that my gastrocs are being stretched
differently between the two versions of this exercise. The only joints
changing their position during the actual stretching exercises are my hips
(flexing). I keep my knees fully extended either way and my ankles fixed in
one of two positions. As far as I know the gastrocs are not supposed to
change their length at all by changes in hip position, only knee and ankle.
Is there some connective tissue link between the stretch of the hamstrings
and the stretch in the gastrocs not predicted by the simple 2 joint models
of these muscles?

Thanks in advance for your thoughts on this matter.

Regards,

--Rick

Richard N. Hinrichs, Ph.D.
Dept. of Kinesiology
Arizona State University
P.O. Box 870404
Tempe, AZ 85287-0404
(1) 480-965-1624 (phone)
(1) 480-965-8108 (fax)
hinrichs@asu.edu (email)
www.public.asu.edu/~hinrichs/ (personal web page)
www.asu.edu/clas/kines/ (Dept. web page)

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