Re: Hamstrings

[Guest guest]

Hey , how are you?

I must beg to differ. I did not look up your reference to the Biomechanics

material. I am, therefore, not aware of whether they used experienced or

inexperienced individuals in the study. This would have an impact on the

outcome. The times that I do recommend or utilize myself, a prone leg curl. I

coach hip extension or raising the leg off of the pad as the person flexes the

knee joint. This can easily be learned to do and increases the " feel " of the

contraction. People who raise the hips are contracting the psoas muscles to

produce flexion of the hip joint to lengthen the hamstring group over the hip

joint as this increases the leverage of the muscle. Muscles are stronger in a

position of length and this action produces that outcome.

I must still disagree with your statement. I would suggest that you try the

prone leg curl exercise and see if you can produce the action that I am talking

about. I obviously am not aware of the type of training that you do. The

majority of my training involves hip extension, hip extension and knee flexion

(GHR) and knee flexion as a tertiary limited use movement. I tried your example

movement and can do the motion without any movement or extension at my knee

joint while extending the hip. This may be a learned action however it can be

done as I and many of my clientele can do it.

Have a great one!

Damien Chiappini

SPFS

Pittsburgh, Pa.

==============

samuel9888 wrote:

Hi Damien,

I'm afraid you are incorrect about being able to maintain the same

degree of knee flexion as you extend at the hip. In " Biomechanics: A

Qualitative Approach for Studying Human Movement "

(Kreighbaum/Barthels), the authors describe the phenomenon as " active

insufficiency " in two-joint muscles. Such biarticulate muscle

fibers " cannot exert enough tension to shorten sufficiently to cause

full ROM in both joints at the same time. "

You can see some acknowledgement of that arrangement in looking at

more current designs of prone leg curl machines, with an angle at the

hip to allow for greater knee flexion. You can also see active

insufficiency at work when people's hips rise upward as they attempt

prone knee flexion: if they try to keep their butt down, they can't

flex through the knee as far.

Merrick, M.A.

ACSM HFI, NSCA-CPT/CSCS, NASM CPT

Bellevue, NE USA

>

> ,

>

> You stated:

> <<<As a biarticulate muscle group, the

> hamstrings don't contract (or relax) very well at both ends at the

> same time. That's why the stiff-legged DL does more for the upper

> hamstrings as they are extending the hip while the distal (bottom)

> end is relaxed. Conversely, when performing seated leg curls, where

> the proximal end is relaxed, the distal end engages more. A way to

> demonstrate this is to stand on one leg and flex the free leg hard

> while flexing forward at the hip: as you straighten up by extending

> the hip, your calf will start to drop. You can't maintain the same

> degree of knee flexion while extending the hip.>>>

>

> ***

> This is an untrue statement. When you extend your hip or flex your

knee the hamstring group is contracting over the length of the muscle

not just at one end, it is not relaxed at the opposite end. The

example you provide is also false. You most certainly can maintain

the same degree of knee flexion as you extend at the hip.

>

> Damien Chiappini

> SPFS

> Pittsburgh,PA.

[Guest guest]

Hello Damien,

Sorry for the delay in responding.

We may be talking about the same thing from different perspectives.

The reason the person " feels " the contraction more when trying to

extend the hip while flexing the knee in the the prone leg curl is

that he/she is trying to exert tension on the muscle at both joints

concurrently. That doesn't mean the person is still getting full ROM

at both joints. Same with GHR: a person doesn't end up in full

active knee flexion simultaneously with full active hip extension.

Active (and passive) insufficiency exists, so I urge you to check out

the terms in the reference I cited or other biomechanical texts. Try

measuring ROM with a goniometer at both joints if you are having

trouble seeing it otherwise. The reason you may be having trouble

seeing it on yourself when doing the movement I described may be due

to extraneous other movement.

Thanks for the dialog.

Merrick, M.A.

ACSM HFI, NSCA-CPT/CSCS, NASM CPT

Bellevue, NE USA

> >

> > ,

> >

> > You stated:

> > <<<As a biarticulate muscle group, the

> > hamstrings don't contract (or relax) very well at both ends at the

> > same time. That's why the stiff-legged DL does more for the upper

> > hamstrings as they are extending the hip while the distal (bottom)

> > end is relaxed. Conversely, when performing seated leg curls,

where the proximal end is relaxed, the distal end engages more. A way

to demonstrate this is to stand on one leg and flex the free leg hard

> > while flexing forward at the hip: as you straighten up by

extending the hip, your calf will start to drop. You can't maintain

the same degree of knee flexion while extending the hip.>>>

> >

> > ***

> > This is an untrue statement. When you extend your hip or flex

your knee the hamstring group is contracting over the length of the

muscle not just at one end, it is not relaxed at the opposite end.

The example you provide is also false. You most certainly can

maintain the same degree of knee flexion as you extend at the hip.

> >

> > Damien Chiappini

> > SPFS

> > Pittsburgh,PA.

>