leg extension attachments and torque curves

Johan Larson johan0larson8comcast0net said:

I've been looking at the leg extension/curl attachments that come standard
with most weight benches. When in use, the weight is placed on the vertical
leg, and the assembly is rotated up approximately ninety degrees. Given
this design, there is very little resistance early in the movement, and
peak resistance is at full extension. In effect, the real range of motion
of the exercise, where you feel the real resistance, is not the full ninety
degrees but rather the final twenty or twenty-five degrees. Isn't that a
problem?

Yes, they suck. They are cheap gizmos that can be added to cheap
equipment to make it look substantially more useful. It is called
"perceived value," which is one of the major marketing ploys for pop
fitness exercise toys and dietary supplements.

Quoted message said:

Actually there are several other popular exercises, including DB Lateral
Raises and Chest Flys that have the same issue. Curiouser and curiouser...

Have you ever really looked to the people who use these exercises as a
significant part of their routine? Did that tell you anything?

"Johan Larson" <johan0larson8comcast0net> wrote in message
news:[email hidden]...

Quoted message said:

I've been looking at the leg extension/curl attachments that come standard
with most weight benches. When in use, the weight is placed on the
vertical
leg, and the assembly is rotated up approximately ninety degrees. Given
this design, there is very little resistance early in the movement, and
peak resistance is at full extension. In effect, the real range of motion
of the exercise, where you feel the real resistance, is not the full
ninety
degrees but rather the final twenty or twenty-five degrees. Isn't that a
problem?

If you geek out and do the math, you'll see that the torque curve is
sin(theta) where theta is the angle from vertical. Now, I'm not sure what
the optimal torque curve would be, but I'll guess that a constant one
would
be a lot better than sin().

Actually there are several other popular exercises, including DB Lateral
Raises and Chest Flys that have the same issue. Curiouser and curiouser...

This whole thing of attaching various pieces of junk to benches and
declaring them gym equipment is reaching epedemic proportions. I know I am
being sarcastic here, but it has always been my opinion that this [censored] was
designed by docs to drum up business.

The only reason that there are not huge numbers of injuries from these
atrocities is that people just don't use them that much. Or if they do,
they don't use much weight.

And don't think torque curves. Think sheer forces with the leg extension
movement. And think of human flesh being coerced into movement that do not
take plae in nature. And think of all the ways that these movements can
destroy joints.

JMW said:

Johan Larson johan0larson8comcast0net said:

I've been looking at the leg extension/curl attachments that come standard
with most weight benches. When in use, the weight is placed on the vertical
leg, and the assembly is rotated up approximately ninety degrees. Given
this design, there is very little resistance early in the movement, and
peak resistance is at full extension. In effect, the real range of motion
of the exercise, where you feel the real resistance, is not the full ninety
degrees but rather the final twenty or twenty-five degrees. Isn't that a
problem?

Yes, they suck. They are cheap gizmos that can be added to cheap
equipment to make it look substantially more useful. It is called
"perceived value," which is one of the major marketing ploys for pop
fitness exercise toys and dietary supplements.

Quoted message said:

Actually there are several other popular exercises, including DB Lateral
Raises and Chest Flys that have the same issue. Curiouser and curiouser...

Have you ever really looked to the people who use these exercises as a
significant part of their routine? Did that tell you anything?

Of course I do, but then look at me? Oh, maybe not, I'm uglier than a
gay mans [censored]-hole.

JMW

JMW <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

Johan Larson johan0larson8comcast0net said:

I've been looking at the leg extension/curl attachments that come
standard with most weight benches. When in use, the weight is placed
on the vertical leg, and the assembly is rotated up approximately
ninety degrees. Given this design, there is very little resistance
early in the movement, and peak resistance is at full extension. In
effect, the real range of motion of the exercise, where you feel the
real resistance, is not the full ninety degrees but rather the final
twenty or twenty-five degrees. Isn't that a problem?

Yes, they suck. They are cheap gizmos that can be added to cheap
equipment to make it look substantially more useful. It is called
"perceived value," which is one of the major marketing ploys for pop
fitness exercise toys and dietary supplements.

Quoted message said:

Actually there are several other popular exercises, including DB
Lateral Raises and Chest Flys that have the same issue. Curiouser and
curiouser...

Have you ever really looked to the people who use these exercises as a
significant part of their routine? Did that tell you anything?

You are saying that despite my geekly musings, DB lateral raises and
chest flys are very effective exercises?

As far as I can tell, for deltoid work, lateral raises are popular, but
popular mainly in group exercise classes, where they are done with those
cute brightly colored DBs. That makes sense, since lateral raises require
a less weight than the obvious alternatives. Over in the freeweights
room, I would expect to see more shoulder presses and vertical rows than
lateral raises.

As for chest flys, I think they rank in popularity behind benchpresses,
and perhaps even behind fairly oddball variations like decline
benchpresses.

If popularity and effectiveness are roughly matched (which I agree is a
big assumption), then lateral raises and chest flys are not the most
effective freeweight exercises for their target muscle groups.

--
Johan Larson Daly City, California

"Lee Michaels" <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

"Johan Larson" <johan0larson8comcast0net> wrote in message
news:[email hidden]...

Quoted message said:

I've been looking at the leg extension/curl attachments that come
standard with most weight benches. When in use, the weight is placed
on the vertical
leg, and the assembly is rotated up approximately ninety degrees.
Given this design, there is very little resistance early in the
movement, and peak resistance is at full extension.

This whole thing of attaching various pieces of junk to benches and
declaring them gym equipment is reaching epedemic proportions. I know
I am being sarcastic here, but it has always been my opinion that this
[censored] was designed by docs to drum up business.

You think leg extensions are dangerous when done with equipment like this
even if the axis of rotation of the machine is matched to the axis of
rotation of the knee?

--
Johan Larson Daly City, California

Johan Larson said:

JMW <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

Johan Larson johan0larson8comcast0net said:

I've been looking at the leg extension/curl attachments that come
standard with most weight benches. When in use, the weight is placed
on the vertical leg, and the assembly is rotated up approximately
ninety degrees. Given this design, there is very little resistance
early in the movement, and peak resistance is at full extension. In
effect, the real range of motion of the exercise, where you feel the
real resistance, is not the full ninety degrees but rather the final
twenty or twenty-five degrees. Isn't that a problem?

Yes, they suck. They are cheap gizmos that can be added to cheap
equipment to make it look substantially more useful. It is called
"perceived value," which is one of the major marketing ploys for pop
fitness exercise toys and dietary supplements.

Quoted message said:

Actually there are several other popular exercises, including DB
Lateral Raises and Chest Flys that have the same issue. Curiouser and
curiouser...

Have you ever really looked to the people who use these exercises as a
significant part of their routine? Did that tell you anything?

You are saying that despite my geekly musings, DB lateral raises and
chest flys are very effective exercises?

As far as I can tell, for deltoid work, lateral raises are popular, but
popular mainly in group exercise classes, where they are done with those
cute brightly colored DBs. That makes sense, since lateral raises require
a less weight than the obvious alternatives. Over in the freeweights
room, I would expect to see more shoulder presses and vertical rows than
lateral raises.

As for chest flys, I think they rank in popularity behind benchpresses,
and perhaps even behind fairly oddball variations like decline
benchpresses.

If popularity and effectiveness are roughly matched (which I agree is a
big assumption), then lateral raises and chest flys are not the most
effective freeweight exercises for their target muscle groups.

Just to prod you into completing your paragraph:

'...not the most effective freeweight exercises for their target muscle
groups. More effective exercises include...'

--
spammage trappage: remove the underscores to reply

I'm going to die rather sooner than I'd like. I tried to protect my
neighbours from crime, and became the victim of it. Complications in
hospital following this resulted in a serious illness. I now need a bone
marrow transplant. Many people around the world are waiting for a marrow
transplant, too. Please volunteer to be a marrow donor:
http://www.abmdr.org.au/
http://www.marrow.org/

Johan Larson johan0larson8comcast0net said:

JMW said:

Johan Larson johan0larson8comcast0net said:

I've been looking at the leg extension/curl attachments that come
standard with most weight benches. When in use, the weight is placed
on the vertical leg, and the assembly is rotated up approximately
ninety degrees. Given this design, there is very little resistance
early in the movement, and peak resistance is at full extension. In
effect, the real range of motion of the exercise, where you feel the
real resistance, is not the full ninety degrees but rather the final
twenty or twenty-five degrees. Isn't that a problem?

Yes, they suck. They are cheap gizmos that can be added to cheap
equipment to make it look substantially more useful. It is called
"perceived value," which is one of the major marketing ploys for pop
fitness exercise toys and dietary supplements.

Quoted message said:

Actually there are several other popular exercises, including DB
Lateral Raises and Chest Flys that have the same issue. Curiouser and
curiouser...

Have you ever really looked to the people who use these exercises as a
significant part of their routine? Did that tell you anything?

You are saying that despite my geekly musings, DB lateral raises and
chest flys are very effective exercises?

No.

Quoted message said:

As far as I can tell, for deltoid work, lateral raises are popular, but
popular mainly in group exercise classes, where they are done with those
cute brightly colored DBs.

You're starting to get the point. Tricep kickbacks are popular, too.

Quoted message said:

That makes sense, since lateral raises require
a less weight than the obvious alternatives. Over in the freeweights
room, I would expect to see more shoulder presses and vertical rows than
lateral raises.

See? You're getting smarter already. Just don't bring the bar above
your nipples for upright rows. Unnecessary and too much risk of
rotator cuff impingement.

Quoted message said:

As for chest flys, I think they rank in popularity behind benchpresses,
and perhaps even behind fairly oddball variations like decline
benchpresses.

If you want to do flyes, use a cable machine.

spodosaurus <spodosaurus@_yahoo_.com> wrote in
news:[email hidden]:

Quoted message said:

Johan Larson said:

JMW <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

Johan Larson <johan0larson8comcast0net> wrote:

>I've been looking at the leg extension/curl attachments that come
>standard with most weight benches. When in use, the weight is placed
>on the vertical leg, and the assembly is rotated up approximately
>ninety degrees. Given this design, there is very little resistance
>early in the movement, and peak resistance is at full extension. In
>effect, the real range of motion of the exercise, where you feel the
>real resistance, is not the full ninety degrees but rather the final
>twenty or twenty-five degrees. Isn't that a problem?

Yes, they suck. They are cheap gizmos that can be added to cheap
equipment to make it look substantially more useful. It is called
"perceived value," which is one of the major marketing ploys for pop
fitness exercise toys and dietary supplements.

>Actually there are several other popular exercises, including DB
>Lateral Raises and Chest Flys that have the same issue. Curiouser
>and curiouser...

Have you ever really looked to the people who use these exercises as
a significant part of their routine? Did that tell you anything?

You are saying that despite my geekly musings, DB lateral raises and
chest flys are very effective exercises?

As far as I can tell, for deltoid work, lateral raises are popular,
but popular mainly in group exercise classes, where they are done
with those cute brightly colored DBs. That makes sense, since lateral
raises require a less weight than the obvious alternatives. Over in
the freeweights room, I would expect to see more shoulder presses
and vertical rows than lateral raises.

As for chest flys, I think they rank in popularity behind
benchpresses, and perhaps even behind fairly oddball variations like
decline benchpresses.

If popularity and effectiveness are roughly matched (which I agree is
a big assumption), then lateral raises and chest flys are not the
most effective freeweight exercises for their target muscle groups.

Just to prod you into completing your paragraph:

'...not the most effective freeweight exercises for their target
muscle groups. More effective exercises include...'

... overhead presses and vertical rows for the deltoids and benchpresses
of various kinds for the pectorals.

--
Johan Larson Daly City, California

Johan Larson johan0larson8comcast0net said:

Lee Michaels said:

Johan Larson' johan0larson8comcast0net said:

I've been looking at the leg extension/curl attachments that come
standard with most weight benches. When in use, the weight is placed
on the vertical
leg, and the assembly is rotated up approximately ninety degrees.
Given this design, there is very little resistance early in the
movement, and peak resistance is at full extension.

This whole thing of attaching various pieces of junk to benches and
declaring them gym equipment is reaching epedemic proportions. I know
I am being sarcastic here, but it has always been my opinion that this
[censored] was designed by docs to drum up business.

You think leg extensions are dangerous when done with equipment like this
even if the axis of rotation of the machine is matched to the axis of
rotation of the knee?

Perhaps it has something to do with shearing forces on the connective
tissues in the knee at and near full extension, yes?

Your knees are not built the same as the hinge on the leg extension
bar.

Johan Larson said:

spodosaurus <spodosaurus@_yahoo_.com> wrote in
news:[email hidden]:

Quoted message said:

Johan Larson said:

JMW <[email hidden]> wrote in
news:[email hidden]:

>Johan Larson <johan0larson8comcast0net> wrote:
>
>
>
>>I've been looking at the leg extension/curl attachments that come
>>standard with most weight benches. When in use, the weight is placed
>>on the vertical leg, and the assembly is rotated up approximately
>>ninety degrees. Given this design, there is very little resistance
>>early in the movement, and peak resistance is at full extension. In
>>effect, the real range of motion of the exercise, where you feel the
>>real resistance, is not the full ninety degrees but rather the final
>>twenty or twenty-five degrees. Isn't that a problem?
>
>Yes, they suck. They are cheap gizmos that can be added to cheap
>equipment to make it look substantially more useful. It is called
>"perceived value," which is one of the major marketing ploys for pop
>fitness exercise toys and dietary supplements.
>
>
>
>>Actually there are several other popular exercises, including DB
>>Lateral Raises and Chest Flys that have the same issue. Curiouser
>>and curiouser...
>
>Have you ever really looked to the people who use these exercises as
>a significant part of their routine? Did that tell you anything?

You are saying that despite my geekly musings, DB lateral raises and
chest flys are very effective exercises?

As far as I can tell, for deltoid work, lateral raises are popular,
but popular mainly in group exercise classes, where they are done
with those cute brightly colored DBs. That makes sense, since lateral
raises require a less weight than the obvious alternatives. Over in
the freeweights room, I would expect to see more shoulder presses
and vertical rows than lateral raises.

As for chest flys, I think they rank in popularity behind
benchpresses, and perhaps even behind fairly oddball variations like
decline benchpresses.

If popularity and effectiveness are roughly matched (which I agree is
a big assumption), then lateral raises and chest flys are not the
most effective freeweight exercises for their target muscle groups.

Just to prod you into completing your paragraph:

'...not the most effective freeweight exercises for their target
muscle groups. More effective exercises include...'

.. overhead presses and vertical rows for the deltoids and benchpresses
of various kinds for the pectorals.

Just for the sake of argument (as I want there to be something to read
in this thread other than social banter when I get back to it tomorrow)
consider these questions:

1. Putting aside the inherent injury potential of upright rows, how do
you see them offering different loading on the deltoids when all you're
changing (for the most part) is the length of the lever arm?

2. When performing a bench press, how do you see the loading being
different to that of a flye movement when, as with upright rows and
lateral raises, the loading on the pectorals is the same and you're just
changing the lever arm? Use shoulder width grip bench presses as the
movement for this thought exercise.

Cheers,

Ari

--
spammage trappage: remove the underscores to reply

I'm going to die rather sooner than I'd like. I tried to protect my
neighbours from crime, and became the victim of it. Complications in
hospital following this resulted in a serious illness. I now need a bone
marrow transplant. Many people around the world are waiting for a marrow
transplant, too. Please volunteer to be a marrow donor:
http://www.abmdr.org.au/
http://www.marrow.org/

Lee Michaels said:

"Johan Larson" <johan0larson8comcast0net> wrote in message
news:[email hidden]...

Quoted message said:

"Lee Michaels" <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

"Johan Larson" <johan0larson8comcast0net> wrote in message
news:[email hidden]...

>I've been looking at the leg extension/curl attachments that come
>standard with most weight benches. When in use, the weight is placed
>on the vertical
>leg, and the assembly is rotated up approximately ninety degrees.
>Given this design, there is very little resistance early in the
>movement, and peak resistance is at full extension.

This whole thing of attaching various pieces of junk to benches and
declaring them gym equipment is reaching epedemic proportions. I know
I am being sarcastic here, but it has always been my opinion that this
[censored] was designed by docs to drum up business.

You think leg extensions are dangerous when done with equipment like this
even if the axis of rotation of the machine is matched to the axis of
rotation of the knee?

It is not what I think.

Leg extensions are only valid as a rehab movement and only a very short
range mavement would be safe.

This has been beat to death here and elsewhere. I think that Krista has an
explanation on her site.

People who are knowledgable don't do this movement.

Unless they have no alternative. I do not trust hip replacements to
heavy leg presses (squats are impractical for this same reason among
several others).

--
spammage trappage: remove the underscores to reply

I'm going to die rather sooner than I'd like. I tried to protect my
neighbours from crime, and became the victim of it. Complications in
hospital following this resulted in a serious illness. I now need a bone
marrow transplant. Many people around the world are waiting for a marrow
transplant, too. Please volunteer to be a marrow donor:
http://www.abmdr.org.au/
http://www.marrow.org/

"Johan Larson" <johan0larson8comcast0net> wrote in message
news:[email hidden]...

Quoted message said:

"Lee Michaels" <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

"Johan Larson" <johan0larson8comcast0net> wrote in message
news:[email hidden]...

Quoted message said:

I've been looking at the leg extension/curl attachments that come
standard with most weight benches. When in use, the weight is placed
on the vertical
leg, and the assembly is rotated up approximately ninety degrees.
Given this design, there is very little resistance early in the
movement, and peak resistance is at full extension.

This whole thing of attaching various pieces of junk to benches and
declaring them gym equipment is reaching epedemic proportions. I know
I am being sarcastic here, but it has always been my opinion that this
[censored] was designed by docs to drum up business.

You think leg extensions are dangerous when done with equipment like this
even if the axis of rotation of the machine is matched to the axis of
rotation of the knee?

It is not what I think.

Leg extensions are only valid as a rehab movement and only a very short
range mavement would be safe.

This has been beat to death here and elsewhere. I think that Krista has an
explanation on her site.

People who are knowledgable don't do this movement.

Lee Michaels said:

Johan Larson' johan0larson8comcast0net said:

Lee Michaels said:

"Johan Larson" <johan0larson8comcast0net> wrote:
>
> I've been looking at the leg extension/curl attachments that come
> standard with most weight benches. When in use, the weight is placed
> on the vertical
> leg, and the assembly is rotated up approximately ninety degrees.
> Given this design, there is very little resistance early in the
> movement, and peak resistance is at full extension.

This whole thing of attaching various pieces of junk to benches and
declaring them gym equipment is reaching epedemic proportions. I know
I am being sarcastic here, but it has always been my opinion that this
[censored] was designed by docs to drum up business.

You think leg extensions are dangerous when done with equipment like this
even if the axis of rotation of the machine is matched to the axis of
rotation of the knee?

It is not what I think.

Leg extensions are only valid as a rehab movement and only a very short
range mavement would be safe.

This has been beat to death here and elsewhere. I think that Krista has an
explanation on her site.

Krista isn't always right. She will "beat to death" the subject of
upright rows, too. Leg extensions are OK if you stop short of lockout
on the concentric stroke. Upright rows are OK if you don't raise the
bar above your nipples. The issue in both is shearing force at full
extension; a general hysteria about the whole movement is unwarranted.

That said, a cable-weighted leg extension machine with more constant
force is preferable.

Quoted message said:

People who are knowledgable don't do this movement.

It has it's place. I don't recommend using it as one's only lower
body exercise.