Seated Chest Press vs Smith Machine Bench Press

On Mon, 11 Feb 2008, latina_liebhaber@yahoo.com wrote:

> Nope, I'm asking why you think weight pushed vertically in a flat bench
> machine isn't harder than *the same weight* pushing horizontally in a
> *mechanically-equivalent* seated chest press machine.

As we've both said, over and over again, THE WEIGHT IS NOT BEING PUSHED
HORIZONTALLY! With both machines, you're moving a weight vertically. In
both cases, it's via a system of levers or pulleys which, as you've said
yourself, are equivalent. The only difference is in the direction in which
the force is applied to the machine. Thus, it's no harder.

Can i ask you a question? Okay, say you have a little weight on the floor,
with a long piece of string tied to the top. You have a pulley wheel fixed
to a table; it's an ideal pulley, so no friction, no inertia of its own,
etc. You decide to lift the weight off the ground. You have two options:
you can either ignore the pulley and just pull vertically on the string,
or thread it round the pulley, so that the string turns the corner, then
pull horizontally on the string. Does that make sense? Now, the question
is: do you think the force you'll need to apply to the string is the same
in both cases, or different?

Bonus question: you have a third option, where the string goes right over
the pulley and then dangles down, and you pull down on the string to lift
the weight, like a cable pulldown. Do you think this is the same or
different to either of the above cases?

tom

--
quick good

<latina_liebhaber@yahoo.com> wrote in message
news:7aec01d1-df19-480c-912c-a2a53c80ff19@v46g2000hsv.googlegroups.com...
> On Feb 11, 11:38 pm, "ATP*" <waxwingsl...@azurepane.com> wrote:
>> We're all laughing at you. Do you want to remain ignorant or do you want
>> to
>> learn something? You can start here:
>>
>> http://en.wikipedia.org/wiki/Pulleys
>
> I already said you can equalize the machines such that pulleys and
> levers are not a factor.
>
Look at the way the forces are translated. I was not referring to mechanical
advantage.

On Feb 12, 8:52 am, "ATP*" <waxwingsl...@azurepane.com> wrote:
>
>
> Look at the way the forces are translated. I was not referring to mechanical
> advantage.

And I keep saying to you, one and all, that you can equalize whatever
forces and factors are involved except the direction of the push and
the gravitational consequences thereof. In any experiment -- even
physicists' thought-experiments -- you try to equalize the variables
which you aren't investigating in order to arrive at the true factors.

I've been saying that the true factor is the direction of the push,
WRT gravity. You guys keep bringing in pulleys and levers and even
the weight of the arms themselves. Those are all variables that can
be equalized between the two machines, conceivably. The very last
thing you absolutely cannot equalize is the direction of the push.
Hence, that is what is *truly* different about a flat bench press
machine and a seated chest press machine.

The direction of the push -- WRT gravity. That's the one final thing,
after all the superficial differences are boiled away.

"Prisoner at War" <prisoner_at_war@yahoo.com> wrote in message
news:d2e5cee3-dbb3-4db9-8006-b814cd3b1205@e6g2000prf.googlegroups.com...
> On Feb 12, 8:52 am, "ATP*" <waxwingsl...@azurepane.com> wrote:
>>
>>
>> Look at the way the forces are translated. I was not referring to
>> mechanical
>> advantage.
>
> And I keep saying to you, one and all, that you can equalize whatever
> forces and factors are involved except the direction of the push and
> the gravitational consequences thereof. In any experiment -- even
> physicists' thought-experiments -- you try to equalize the variables
> which you aren't investigating in order to arrive at the true factors.
>
> I've been saying that the true factor is the direction of the push,
> WRT gravity. You guys keep bringing in pulleys and levers and even
> the weight of the arms themselves. Those are all variables that can
> be equalized between the two machines, conceivably. The very last
> thing you absolutely cannot equalize is the direction of the push.
> Hence, that is what is *truly* different about a flat bench press
> machine and a seated chest press machine.
>
> The direction of the push -- WRT gravity. That's the one final thing,
> after all the superficial differences are boiled away.

This is not an experiment and the principles in question are not open to
debate. What we are telling you comes from solving problems in physics,
statics and dynamics. Your feelings or intuition are wrong, the standard
science is right and easily demonstrated.

On Feb 12, 11:59 pm, Prisoner at War <prisoner_at_...@yahoo.com>
wrote:
> On Feb 12, 8:52 am, "ATP*" <waxwingsl...@azurepane.com> wrote:
>
>
>
> > Look at the way the forces are translated. I was not referring to mechanical
> > advantage.
>
> And I keep saying to you, one and all, that you can equalize whatever
> forces and factors are involved except the direction of the push and
> the gravitational consequences thereof. In any experiment -- even
> physicists' thought-experiments -- you try to equalize the variables
> which you aren't investigating in order to arrive at the true factors.
>
> I've been saying that the true factor is the direction of the push,
> WRT gravity. You guys keep bringing in pulleys and levers and even
> the weight of the arms themselves. Those are all variables that can
> be equalized between the two machines, conceivably. The very last
> thing you absolutely cannot equalize is the direction of the push.
> Hence, that is what is *truly* different about a flat bench press
> machine and a seated chest press machine.
>
> The direction of the push -- WRT gravity. That's the one final thing,
> after all the superficial differences are boiled away.

I don't understand your point. Gravity makes mass fall regardless of
direction. Gravity does not
make it easier for people to push weight horizontally than vertically.

Although this is not a great example, let's consider free weights for
a second. No machines and no
levers (well, except for the human "machine" and our bodies' levers),
is it easier for you to push out
free weight(s) horizontally than lift the same weight(s) upwards or
overhead?

Although pushing a weight is not equivalent to discussing projectiles,
we might be able to use
throwing a ball to make the point clearer. For any particular speed,
a ball will go furthest if thrown 45
degrees to the horizontal. By your reasoning, a ball should go
farther if thrown horizontally.

On Feb 13, 6:38 am, "ATP*" <waxwingsl...@azurepane.com> wrote:
>
>
> This is not an experiment and the principles in question are not open to
> debate. What we are telling you comes from solving problems in physics,
> statics and dynamics. Your feelings or intuition are wrong, the standard
> science is right and easily demonstrated.


I'm not debating your principles about the pulley and leverage and
whatnot.

They simply don't apply in this case. The different machines can have
an equal number of pulleys and so forth working in exactly the same
manner between them (you must compare like with like, apples with
apples). What would still be different is the direction of the push.

That difference, due to gravity, is what accounts for the experience
of one machine offering a more challenging exercise than the other.

On Feb 13, 10:31 am, Bartleby <arroy...@hotmail.com> wrote:
>
>
> I don't understand your point. Gravity makes mass fall regardless of
> direction.

Yes, but there is force involved here, motion. I mean, look at
something like the martial art akido, which has the express aim of
using the opponent's own momentum and weight against him. You don't
win by going head-on against your opponent's force (which is analogous
to pushing a weight vertically, in the total opposite direction of
gravity), but you have a much better chance when you deflecting your
opponent's force (analogous to pushing horizontally, somewhat away
from the full effect of gravity).

> Gravity does not
> make it easier for people to push weight horizontally than vertically.

If you're applying force against a weight vertically, you are working
against 100% of gravity, are you not?

If you're applying force against a weight horizontally, you are
working against gravity only "100-n%"....

> Although this is not a great example, let's consider free weights for
> a second. No machines and no
> levers (well, except for the human "machine" and our bodies' levers),
> is it easier for you to push out
> free weight(s) horizontally than lift the same weight(s) upwards or
> overhead?
>
> Although pushing a weight is not equivalent to discussing projectiles,

It is in the sense of force applied and the direction thereof.

> we might be able to use
> throwing a ball to make the point clearer.

And so I have already!

> For any particular speed,
> a ball will go furthest if thrown 45
> degrees to the horizontal. By your reasoning, a ball should go
> farther if thrown horizontally.

45 degrees is still more "horizontal" than 90 degrees is -- which is a
flat bench press (okay no FBP is perfectly 90 degrees, but you get my
point). Using a FBP machine is harder than a mechanically equivalent
seated chest press machine that works the same muscles because of the
direction of the force applied.

Because why else would one be harder to perform than the other? Those
other guys keep talking about pulleys and such, but I already said
that even with mechanically equivalent machines one would still be
harder to perform than the other. So it seems that this debate comes
down to whether machine design is the deciding factor. Because if it
is, than mechanically equivalent machines would render both positions
equally difficult to perform. I'm claiming that one would still be
harder than the other. If I am wrong about gravity and the direction
of the force applied against it, what is the cause then? Remember, we
don't have pulleys involved anymore between two mechanically
equivalent machines.

On Feb 12, 6:25 am, Tom Anderson <t...@urchin.earth.li> wrote:
> On Mon, 11 Feb 2008, latina_liebha...@yahoo.com wrote:
> > Nope, I'm asking why you think weight pushed vertically in a flat bench
> > machine isn't harder than *the same weight* pushing horizontally in a
> > *mechanically-equivalent* seated chest press machine.
>
> As we've both said, over and over again, THE WEIGHT IS NOT BEING PUSHED
> HORIZONTALLY! With both machines, you're moving a weight vertically. In
> both cases, it's via a system of levers or pulleys which, as you've said
> yourself, are equivalent.

I NEVER said both machines ARE equivalent AS IS. I said they COULD BE
MADE mechanically equivalent so that any pulleys and levers are
FACTORED OUT.

> The only difference is in the direction in which
> the force is applied to the machine. Thus, it's no harder.

Again, my claim is that MECHANICALLY EQUIVALENT machines would STILL
exhibit different difficulties when using them, and that that
difference is due to the direction in which force is applied, WRT
gravity.

Look, we're obviously in three-blind-men-and-an-elephant territory
here. If you would succeed against my argument, you must succeed from
within it. Using a different situation than that with which I'm
contending the issue is like using an apple to my orange -- not the
same thing, though both fruits.

> Can i ask you a question? Okay, say you have a little weight on the floor,
> with a long piece of string tied to the top. You have a pulley wheel fixed
> to a table; it's an ideal pulley, so no friction, no inertia of its own,
> etc. You decide to lift the weight off the ground. You have two options:
> you can either ignore the pulley and just pull vertically on the string,
> or thread it round the pulley, so that the string turns the corner, then
> pull horizontally on the string. Does that make sense? Now, the question
> is: do you think the force you'll need to apply to the string is the same
> in both cases, or different?
>
> Bonus question: you have a third option, where the string goes right over
> the pulley and then dangles down, and you pull down on the string to lift
> the weight, like a cable pulldown. Do you think this is the same or
> different to either of the above cases?

"Different" to both questions.

But again, I don't see why you keep going on about pulleys. I'm
talking about machines without pulleys (or with pulley systems such
that they are "mechanically equivalent" and thus "cancel out" in their
effects relative to one another's difficulty of use). You keep
wanting to talk about one machine with a pulley and one without. Do
you see why we're not even having the same conversation?

Now I'm not claiming I have God's Word on these matters -- only my
own, which is all I know. If you've got news for me, well, that's
what a newsgroup is for! Even old news, about pulleys and such...but
you won't make any headway in a conversation with me over this matter
if you insist on using the situation you have in mind instead of the
situation I have in mind. It seems to me that I have a specific
situation in mind, and you keep wanting to tell me I'm wrong given
that different situation you have in your mind.

Again, no pulleys are involved. I just don't know why you keep
harking back to that.

> tom
>
> --
> quick good

On Feb 13, 9:51*pm, Prisoner at War <prisoner_at_...@yahoo.com> wrote:
> On Feb 13, 10:31 am, Bartleby <arroy...@hotmail.com> wrote:
>
>
>
> > I don't understand your point. *Gravity makes mass fall regardless of
> > direction.
>
> Yes, but there is force involved here, motion. *I mean, look at
> something like the martial art akido, which has the express aim of
> using the opponent's own momentum and weight against him. *You don't
> win by going head-on against your opponent's force (which is analogous
> to pushing a weight vertically, in the total opposite direction of
> gravity), but you have a much better chance when you deflecting your
> opponent's force (analogous to pushing horizontally, somewhat away
> from the full effect of gravity).

"The full effect of gravity" is present whether an object is moving
horizontally or vertically.

I don't get your aikido metaphor. If I am standing and pushing against
someone who is standing and pushing against me, I am
exerting force more or less horizontally. I can understand how
deflecting my opponent's force would be potentially advantageous, but
I don't see the relationship to the issue being discussed
>
> > *Gravity does not
> > make it easier for people to push weight horizontally than vertically.
>
> If you're applying force against a weight vertically, you are working
> against 100% of gravity, are you not?

The same gravitational force applies whether I am lifting a weight
vertically or horizontally. I can lift far more free weight
vertically as in a deadlift or a squat or a shoulder press than I can
by pushing a weight out horizontally, but that does not
mean that gravitational force is lessened by moving a weight upwards.
You want to compare apples with apples so let's
eliminate the machines entirely.
>
> If you're applying force against a weight horizontally, you are
> working against gravity only "100-n%"....

Not true. Please cite verbatim a physics text which says this.
>
> > Although this is not a great example, let's consider free weights for
> > a second. *No machines and no
> > levers (well, except for the human "machine" and our bodies' levers),
> > is it easier for you to push out
> > free weight(s) horizontally than lift the same weight(s) upwards or
> > overhead?
>
> > Although pushing a weight is not equivalent to discussing projectiles,
>
> It is in the sense of force applied and the direction thereof.
>
> > we might be able to use
> > throwing a ball to make the point clearer.
>
> And so I have already!
>
> > *For any particular speed,
> > a ball will go furthest if thrown 45
> > degrees to the horizontal. *By your reasoning, a ball should go
> > farther if thrown horizontally.
>
> 45 degrees is still more "horizontal" than 90 degrees is -- which is a
> flat bench press (okay no FBP is perfectly 90 degrees, but you get my
> point). *Using a FBP machine is harder than a mechanically equivalent
> seated chest press machine that works the same muscles because of the
> direction of the force applied.

Would you agree that 45 degrees is a midpoint between straight up and
straight out? Something
has to go up to get to 45 degrees. I don't use machines all that
much, but I know that there are different
machines, e.g., Strive, HammerStrength, etc. There are cams and
levers that differentiate
one (well-maintained) machine from the next and which don't exist with
free weight exercises.
These factors make it difficult to compare free weight lifts with
machines - or even between different
kinds of machines.. I would never assume I could do a free weight
lift with the same weight I move
on a machine - whether the machine has me lifting vertically or
horizontally. This goes beyond the
contribution of stabilizer muscles.

I do not mean to suggest that machines can't be helpful.
>
> Because why else would one be harder to perform than the other? *Those
> other guys keep talking about pulleys and such, but I already said
> that even with mechanically equivalent machines one would still be
> harder to perform than the other. *

Some machines are harder to use than others. Strive, for example,
suposedly
allows you to focus on where your sticking point is - at the outset,
midway or near the end.

I used a HammerStrength incline bench press tonight. I'm glad the
machine helped to support the
weight as I was pushing out out and slightly up. I was not working
against 100 -n% gravity! Simply stated, in the
bottom position the lever is rotated out of the horizontal and not all
of the weight force of the plates was directed
against me. As I moved the weight up and the lever arm moved towards
the horizontal, more of the weight was
directed against me. If you spotted me doing a flat bench and helped
out a lot at the bottom position and gradually
lessened your assistance as my arm extended and the weight went up, I
could do a mighty fine bench press (for me)
- but that does not mean that gravity is minimized by lifting a weight
vertically!


So it seems that this debate comes
> down to whether machine design is the deciding factor. *Because if it
> is, than mechanically equivalent machines would render both positions
> equally difficult to perform. *I'm claiming that one would still be
> harder than the other. *If I am wrong about gravity and the direction
> of the force applied against it, what is the cause then? *Remember, we
> don't have pulleys involved anymore between two mechanically
> equivalent machines.

If you could provide mechanically equivalent machines where the lever
arms are reducing the
weight directed against the lifter by the same percentage throughout
the phases of the lift and
where the same muscle groups are equally engaged,you would see that it
would be irrelevant
whether one is pushing out or up. Gravitational force is an
unvarying constant.

"Prisoner at War" <prisoner_at_war@yahoo.com> wrote in message
news:6ecb05c8-e390-4c35-8655-48b6bc6abb88@q77g2000hsh.googlegroups.com...
> On Feb 13, 6:38 am, "ATP*" <waxwingsl...@azurepane.com> wrote:
>>
>>
>> This is not an experiment and the principles in question are not open to
>> debate. What we are telling you comes from solving problems in physics,
>> statics and dynamics. Your feelings or intuition are wrong, the standard
>> science is right and easily demonstrated.
>
>
> I'm not debating your principles about the pulley and leverage and
> whatnot.
>
> They simply don't apply in this case. The different machines can have
> an equal number of pulleys and so forth working in exactly the same
> manner between them (you must compare like with like, apples with
> apples). What would still be different is the direction of the push.
>
> That difference, due to gravity, is what accounts for the experience
> of one machine offering a more challenging exercise than the other.
>

A wrap over one fixed axle pulley changes the direction of the force
applied. Aside from an almost negligible loss due to friction, that's all it
does. The direction that the cable is pulled does not change the amount of
force that has to be applied to lift the weight stack. If you, for example,
take a cable from a cable crossover machine, you can change the direction of
applied force without changing the amount of force that needs to be applied
(with the exception of the amount of energy it takes to lift the mass of the
cable and your arms, which is almost negligible and not what we are arguing
about). Your biomechanics would change, but if you were pulling that cable
with a spring scale you would see that the force applied does not. Same
principle applies if levers are moving weight stacks or puilling cables.

On Wed, 13 Feb 2008, Prisoner at War wrote:

> On Feb 12, 6:25 am, Tom Anderson <t...@urchin.earth.li> wrote:
>> On Mon, 11 Feb 2008, latina_liebha...@yahoo.com wrote:
>>> Nope, I'm asking why you think weight pushed vertically in a flat bench
>>> machine isn't harder than *the same weight* pushing horizontally in a
>>> *mechanically-equivalent* seated chest press machine.
>>
>> As we've both said, over and over again, THE WEIGHT IS NOT BEING PUSHED
>> HORIZONTALLY! With both machines, you're moving a weight vertically. In
>> both cases, it's via a system of levers or pulleys which, as you've said
>> yourself, are equivalent.
>
> I NEVER said both machines ARE equivalent AS IS. I said they COULD BE
> MADE mechanically equivalent so that any pulleys and levers are
> FACTORED OUT.
>
>> The only difference is in the direction in which
>> the force is applied to the machine. Thus, it's no harder.
>
> Again, my claim is that MECHANICALLY EQUIVALENT machines would STILL
> exhibit different difficulties when using them, and that that
> difference is due to the direction in which force is applied, WRT
> gravity.
>
> Look, we're obviously in three-blind-men-and-an-elephant territory
> here.

I'd say it was three-billy-goats-and-a-bridge territory myself, but hey.

>> Can i ask you a question? Okay, say you have a little weight on the floor,
>> with a long piece of string tied to the top. You have a pulley wheel fixed
>> to a table; it's an ideal pulley, so no friction, no inertia of its own,
>> etc. You decide to lift the weight off the ground. You have two options:
>> you can either ignore the pulley and just pull vertically on the string,
>> or thread it round the pulley, so that the string turns the corner, then
>> pull horizontally on the string. Does that make sense? Now, the question
>> is: do you think the force you'll need to apply to the string is the same
>> in both cases, or different?
>>
>> Bonus question: you have a third option, where the string goes right over
>> the pulley and then dangles down, and you pull down on the string to lift
>> the weight, like a cable pulldown. Do you think this is the same or
>> different to either of the above cases?
>
> "Different" to both questions.

Okay, thanks. You're wrong.

That's just not how physics works. Whatever the angle of the string, you
have to apply the same force to it to lift the weight.

> But again, I don't see why you keep going on about pulleys.

The crux of the problem relates to bending a force through an angle: if
you're pushing horizontally but moving a weight up, is that as difficult
as moving a weight up (like i say) or horizontally (like you say)? A
pulley is a good way of setting up a system like that, which is why
pulleys keep getting mentioned. The same goes for levers.

> I'm talking about machines without pulleys (or with pulley systems such
> that they are "mechanically equivalent" and thus "cancel out" in their
> effects relative to one another's difficulty of use). You keep wanting
> to talk about one machine with a pulley and one without.

If you like, i could have phrased my question with a lever instead of a
pulley. Or with some hydraulic pistons, or two axles with a universal
joint. They're all entirely equivalent.

> Do you see why we're not even having the same conversation?

Well, that's been clear for quite a while.

> It seems to me that I have a specific situation in mind, and you keep
> wanting to tell me I'm wrong given that different situation you have in
> your mind.

I'm generalising. I thought it was obvious that the fine detail of the
linkage between the handles and the weights didn't matter (provided
there's no mechanical advantage), but i guess it's not.

tom

--
Orange paint menace

On Feb 13, 11:16 pm, Bartleby <arroy...@hotmail.com> wrote:
>
>
> "The full effect of gravity" is present whether an object is moving
> horizontally or vertically.

In a general sense, sure.

But imagine a tug-of-war, with both sides evenly matched. Now you
come in and pull at a direction perpendicular to both forces, on
either side. Assuming you have enough force applied, don't you think
you would have an effect? Hence my akido analogy.

> I don't get your aikido metaphor. If I am standing and pushing against
> someone who is standing and pushing against me, I am
> exerting force more or less horizontally. I can understand how
> deflecting my opponent's force would be potentially advantageous, but
> I don't see the relationship to the issue being discussed

Well, any analogy will rip if you stretch it far enough. I meant only
to illustrate by way of comparison the notion that the direction of
the force applied is an important consideration. But we can forget
this akido example if it will only introduce more complexity to the
discussion.

> The same gravitational force applies whether I am lifting a weight
> vertically or horizontally.

Semantics here: yes, it applies "equally" in the sense that you plug
in the same number for gravity no matter the equation (unless you get
very far away from the earth, of course, but we're not talking about
such cases), but no, it does not apply "equally" because its effect
can be skewered by the force applied against it.

Again, I have in mind, to use yet another illustration, the tug-of-
war: pushing up a weight against gravity would be analogous to the two
sides tugging 180 degrees away from each other; pushing forward a
weight against gravity would be (roughly) analogous to a third party
coming along tugging 90 degrees to both parties.

> I can lift far more free weight
> vertically as in a deadlift or a squat or a shoulder press than I can
> by pushing a weight out horizontally, but that does not
> mean that gravitational force is lessened by moving a weight upwards.
> You want to compare apples with apples so let's
> eliminate the machines entirely.

Um, no, we can't eliminate the machines because, well, the question is
precisely why one machine is easier than the other despite the muscles
being worked the same way. Obviously, when you talk about a deadlift
compared to a shoulder press -- or even the squat -- you're talking
about very different things.

> Not true. Please cite verbatim a physics text which says this.

If I tell you "sdfdf" means "lkjhf" and you say no it doesn't, it's up
to you to provide the proof.

> Would you agree that 45 degrees is a midpoint between straight up and
> straight out? Something
> has to go up to get to 45 degrees. I don't use machines all that
> much, but I know that there are different
> machines, e.g., Strive, HammerStrength, etc. There are cams and
> levers that differentiate
> one (well-maintained) machine from the next and which don't exist with
> free weight exercises.
> These factors make it difficult to compare free weight lifts with
> machines - or even between different
> kinds of machines.. I would never assume I could do a free weight
> lift with the same weight I move
> on a machine - whether the machine has me lifting vertically or
> horizontally. This goes beyond the
> contribution of stabilizer muscles.

We're not comparing free-weight exercises here to machine-stabilized
ones. We are very clearly one machine with another. And, what's
more, I am comparing mechanically equivalent machines, where leverage
is concerned. I have been saying that, all else being equal, the
direction of force exerted against gravity makes a significant
difference.

> I do not mean to suggest that machines can't be helpful.

They certainly have their place, even if for nothing else than for the
sake of variety!

> Some machines are harder to use than others. Strive, for example,
> suposedly
> allows you to focus on where your sticking point is - at the outset,
> midway or near the end.

Yes, some machines are harder to use, as exercises, than others, which
would purport to model the same exercise.

I'm talking about *mechanically equivalent* ones.

> I used a HammerStrength incline bench press tonight. I'm glad the
> machine helped to support the
> weight as I was pushing out out and slightly up. I was not working
> against 100 -n% gravity!

Note that that's an incline press machine. Quite a different "muscle
motion" than what's being discussed.

> Simply stated, in the
> bottom position the lever is rotated out of the horizontal and not all
> of the weight force of the plates was directed
> against me. As I moved the weight up and the lever arm moved towards
> the horizontal, more of the weight was
> directed against me. If you spotted me doing a flat bench and helped
> out a lot at the bottom position and gradually
> lessened your assistance as my arm extended and the weight went up, I
> could do a mighty fine bench press (for me)
> - but that does not mean that gravity is minimized by lifting a weight
> vertically!

Be that as it may, we're not talking about the incline press, but the
flat bench press. Our issue concerns why a seated chest press machine
is easier to use than one where the user is laying down on his back.

> If you could provide mechanically equivalent machines where the lever
> arms are reducing the
> weight directed against the lifter by the same percentage throughout
> the phases of the lift and
> where the same muscle groups are equally engaged,you would see that it
> would be irrelevant
> whether one is pushing out or up. Gravitational force is an
> unvarying constant.

And that's just the crux of the matter: would mechanically equivalent
machines be equally easy/difficult? I say no, you say yes. You say
yes because gravity is constant; I say no because while gravity itself
is constant, its "potency" can be "diluted" by the direction against
which it is contested.

Remember, gravity is being worked against here. Gravity would only be
constant in "bottom-line terms" if the weight is simply being dropped
to the earth. We are, however, lifting that weight, and the direction
of our lift/work/push matters.

Tell you what. I'm going to ask a physics professor or two. I'll
report back when I get an answer, whether I'm right or wrong. I
promise.

On Feb 14, 7:21 am, Tom Anderson <t...@urchin.earth.li> wrote:
>
> I'd say it was three-billy-goats-and-a-bridge territory myself, but hey.

Heh, more like two apples, two oranges, a banana, and innumerable
keystrokes and dead neurons.

> Okay, thanks. You're wrong.
>
> That's just not how physics works. Whatever the angle of the string, you
> have to apply the same force to it to lift the weight.

The pulleys make the job easier. That's why you have pulleys.
Machines make life easier.

Because it's easier, there is less force used per inch/feet/drop of
sweat/whatever.

That's why a free-weight exercise will be harder than one performed in
a machine.

> The crux of the problem relates to bending a force through an angle: if
> you're pushing horizontally but moving a weight up,

AHA!

I'm not envisioning the weight being moved up. I'm envisioning that
weight being moved forward. In the seated version.

No wonder you keep returning to pulleys! Indeed, how else to apply
force through an angle!

Anyway, the last time you raised this issue (though not so
explicitly), I mentioned that both machines could be engineered to be
mechanically equivalent such that their pulley actions are not
different at all....

> is that as difficult
> as moving a weight up (like i say) or horizontally (like you say)? A
> pulley is a good way of setting up a system like that, which is why
> pulleys keep getting mentioned. The same goes for levers.

Again, if you engineer both machines, the prone and the seated
versions, to be "mechanically equivalent," the "pulley action" would
not be different between them, and hence "cancel out" as variables
explaining why one offered more difficulty than the other.

Now I might still turn out to be wrong on that final score, but that
final score is what I'm arguing -- not over pulleys and how they work,
et cetera et cetera et cetera...which is why I'd mentioned that in
contesting me you have to contest from *within* my argument, not from
without it, or else we wind up having two different, though related,
conversations: "Watt's on first? Hu's on second?"

> If you like, i could have phrased my question with a lever instead of a
> pulley. Or with some hydraulic pistons, or two axles with a universal
> joint. They're all entirely equivalent.

Yes, and *both* machines have them such that there is no mechanical
difference between them. With no mechanical difference between them,
we can get down to my argument that direction of force against gravity
is the determinant in exercise difficulty.

Can you just forget about pulleys and levers? I don't mean that they
don't exist in these machines -- rather, that they exist in such a
state between the two machines such that they "cancel out" as
factors. What don't you get about that?

Now maybe it's physically impossible to construct such machines,
machines with different user positions to be mechanically equivalent
-- maybe there's just no way in this universe that two machines could
be made such that their mechanical actions are so equivalent to one
another such that they cancel out in any work-comparison with one
another. I can't imagine why not, but if that's your argument, then
that's that.

But you haven't said that. You keep going back to pulleys and geegaws
of this sort when I keep saying that they can be made mechanically
equivalent so that they are no longer a point of difference between
the two machines. It's like I'm saying I don't want fries with that
and you keep asking whether I would like ketchup with my fries...are
you really saying that the fries just come with the order regardless
of what I want?

Again, there are no pulleys, etc. involved here. Not because they
don't exist, but because they're *mechanically equivalent* such that
they factor one another out as differences between the two machines.

> Well, that's been clear for quite a while.

So why not talk to me about what I'm talking about -- since you're
replying to me -- instead of continuing to go on about oranges to my
apples??

> I'm generalising. I thought it was obvious that the fine detail of the
> linkage between the handles and the weights didn't matter (provided
> there's no mechanical advantage), but i guess it's not.

It's obvious it doesn't matter.

There is no mechanical advantage between mechanically equivalent
machines.

You (and the others) keep bringing up mechanical advantage with
pulleys and so forth, when I keep saying that there is no mechanical
advantage between mechanically equivalent machines.

> tom
>
> --
> Orange paint menace

On Feb 14, 10:36 am, Prisoner at War <prisoner_at_...@yahoo.com>
wrote:
> On Feb 13, 11:16 pm, Bartleby <arroy...@hotmail.com> wrote:
>
>
>
> > "The full effect of gravity" is present whether an object is moving
> > horizontally or vertically.
>
> In a general sense, sure.
>
> But imagine a tug-of-war, with both sides evenly matched. Now you
> come in and pull at a direction perpendicular to both forces, on
> either side. Assuming you have enough force applied, don't you think
> you would have an effect? Hence my akido analogy.
>
> > I don't get your aikido metaphor. If I am standing and pushing against
> > someone who is standing and pushing against me, I am
> > exerting force more or less horizontally. I can understand how
> > deflecting my opponent's force would be potentially advantageous, but
> > I don't see the relationship to the issue being discussed
>
> Well, any analogy will rip if you stretch it far enough. I meant only
> to illustrate by way of comparison the notion that the direction of
> the force applied is an important consideration. But we can forget
> this akido example if it will only introduce more complexity to the
> discussion.
>
> > The same gravitational force applies whether I am lifting a weight
> > vertically or horizontally.
>
> Semantics here: yes, it applies "equally" in the sense that you plug
> in the same number for gravity no matter the equation (unless you get
> very far away from the earth, of course, but we're not talking about
> such cases), but no, it does not apply "equally" because its effect
> can be skewered by the force applied against it.
>
> Again, I have in mind, to use yet another illustration, the tug-of-
> war: pushing up a weight against gravity would be analogous to the two
> sides tugging 180 degrees away from each other; pushing forward a
> weight against gravity would be (roughly) analogous to a third party
> coming along tugging 90 degrees to both parties.
>
> > I can lift far more free weight
> > vertically as in a deadlift or a squat or a shoulder press than I can
> > by pushing a weight out horizontally, but that does not
> > mean that gravitational force is lessened by moving a weight upwards.
> > You want to compare apples with apples so let's
> > eliminate the machines entirely.
>
> Um, no, we can't eliminate the machines because, well, the question is
> precisely why one machine is easier than the other despite the muscles
> being worked the same way. Obviously, when you talk about a deadlift
> compared to a shoulder press -- or even the squat -- you're talking
> about very different things.
>
> > Not true. Please cite verbatim a physics text which says this.
>
> If I tell you "sdfdf" means "lkjhf" and you say no it doesn't, it's up
> to you to provide the proof.
>
> > Would you agree that 45 degrees is a midpoint between straight up and
> > straight out? Something
> > has to go up to get to 45 degrees. I don't use machines all that
> > much, but I know that there are different
> > machines, e.g., Strive, HammerStrength, etc. There are cams and
> > levers that differentiate
> > one (well-maintained) machine from the next and which don't exist with
> > free weight exercises.
> > These factors make it difficult to compare free weight lifts with
> > machines - or even between different
> > kinds of machines.. I would never assume I could do a free weight
> > lift with the same weight I move
> > on a machine - whether the machine has me lifting vertically or
> > horizontally. This goes beyond the
> > contribution of stabilizer muscles.
>
> We're not comparing free-weight exercises here to machine-stabilized
> ones. We are very clearly one machine with another. And, what's
> more, I am comparing mechanically equivalent machines, where leverage
> is concerned. I have been saying that, all else being equal, the
> direction of force exerted against gravity makes a significant
> difference.
>
> > I do not mean to suggest that machines can't be helpful.
>
> They certainly have their place, even if for nothing else than for the
> sake of variety!
>
> > Some machines are harder to use than others. Strive, for example,
> > suposedly
> > allows you to focus on where your sticking point is - at the outset,
> > midway or near the end.
>
> Yes, some machines are harder to use, as exercises, than others, which
> would purport to model the same exercise.
>
> I'm talking about *mechanically equivalent* ones.
>
> > I used a HammerStrength incline bench press tonight. I'm glad the
> > machine helped to support the
> > weight as I was pushing out out and slightly up. I was not working
> > against 100 -n% gravity!
>
> Note that that's an incline press machine. Quite a different "muscle
> motion" than what's being discussed.
>
> > Simply stated, in the
> > bottom position the lever is rotated out of the horizontal and not all
> > of the weight force of the plates was directed
> > against me. As I moved the weight up and the lever arm moved towards
> > the horizontal, more of the weight was
> > directed against me. If you spotted me doing a flat bench and helped
> > out a lot at the bottom position and gradually
> > lessened your assistance as my arm extended and the weight went up, I
> > could do a mighty fine bench press (for me)
> > - but that does not mean that gravity is minimized by lifting a weight
> > vertically!
>
> Be that as it may, we're not talking about the incline press, but the
> flat bench press. Our issue concerns why a seated chest press machine
> is easier to use than one where the user is laying down on his back.
>
> > If you could provide mechanically equivalent machines where the lever
> > arms are reducing the
> > weight directed against the lifter by the same percentage throughout
> > the phases of the lift and
> > where the same muscle groups are equally engaged,you would see that it
> > would be irrelevant
> > whether one is pushing out or up. Gravitational force is an
> > unvarying constant.
>
> And that's just the crux of the matter: would mechanically equivalent
> machines be equally easy/difficult? I say no, you say yes. You say
> yes because gravity is constant; I say no because while gravity itself
> is constant, its "potency" can be "diluted" by the direction against
> which it is contested.
>
> Remember, gravity is being worked against here. Gravity would only be
> constant in "bottom-line terms" if the weight is simply being dropped
> to the earth. We are, however, lifting that weight, and the direction
> of our lift/work/push matters.
>
> Tell you what. I'm going to ask a physics professor or two. I'll
> report back when I get an answer, whether I'm right or wrong. I
> promise.

Very good. Ask a physics prof. I'd very much like to read his/her
verbatim
answer (and where s/he teaches). The question is whether, given
"mechanically
equivalent" machines, the exercise would be easier to do seated than
supine
purely due to gravitational factors. Ideally, this physics prof
spends some time
in the gym and knows what you're asking about when you bring up Smith
machines
and seated bench press machines.

"Prisoner at War" <prisoner_at_war@yahoo.com> wrote in message
news:da56bb69-0ffc-412e-b030-319d98b82a08@q78g2000hsh.googlegroups.com...
> On Feb 14, 7:21 am, Tom Anderson <t...@urchin.earth.li> wrote:
>>
>> I'd say it was three-billy-goats-and-a-bridge territory myself, but hey.
>
> Heh, more like two apples, two oranges, a banana, and innumerable
> keystrokes and dead neurons.
>
>> Okay, thanks. You're wrong.
>>
>> That's just not how physics works. Whatever the angle of the string, you
>> have to apply the same force to it to lift the weight.
>
> The pulleys make the job easier. That's why you have pulleys.
> Machines make life easier.
>
> Because it's easier, there is less force used per inch/feet/drop of
> sweat/whatever.
>
> That's why a free-weight exercise will be harder than one performed in
> a machine.
>
>> The crux of the problem relates to bending a force through an angle: if
>> you're pushing horizontally but moving a weight up,
>
> AHA!
>
> I'm not envisioning the weight being moved up. I'm envisioning that
> weight being moved forward. In the seated version.
>
> No wonder you keep returning to pulleys! Indeed, how else to apply
> force through an angle!
>
> Anyway, the last time you raised this issue (though not so
> explicitly), I mentioned that both machines could be engineered to be
> mechanically equivalent such that their pulley actions are not
> different at all....
>
>> is that as difficult
>> as moving a weight up (like i say) or horizontally (like you say)? A
>> pulley is a good way of setting up a system like that, which is why
>> pulleys keep getting mentioned. The same goes for levers.
>
> Again, if you engineer both machines, the prone and the seated
> versions, to be "mechanically equivalent," the "pulley action" would
> not be different between them, and hence "cancel out" as variables
> explaining why one offered more difficulty than the other.
>
> Now I might still turn out to be wrong on that final score, but that
> final score is what I'm arguing -- not over pulleys and how they work,
> et cetera et cetera et cetera...which is why I'd mentioned that in
> contesting me you have to contest from *within* my argument, not from
> without it, or else we wind up having two different, though related,
> conversations: "Watt's on first? Hu's on second?"
>
>> If you like, i could have phrased my question with a lever instead of a
>> pulley. Or with some hydraulic pistons, or two axles with a universal
>> joint. They're all entirely equivalent.
>
> Yes, and *both* machines have them such that there is no mechanical
> difference between them. With no mechanical difference between them,
> we can get down to my argument that direction of force against gravity
> is the determinant in exercise difficulty.
>
> Can you just forget about pulleys and levers? I don't mean that they
> don't exist in these machines -- rather, that they exist in such a
> state between the two machines such that they "cancel out" as
> factors. What don't you get about that?
>
> Now maybe it's physically impossible to construct such machines,
> machines with different user positions to be mechanically equivalent
> -- maybe there's just no way in this universe that two machines could
> be made such that their mechanical actions are so equivalent to one
> another such that they cancel out in any work-comparison with one
> another. I can't imagine why not, but if that's your argument, then
> that's that.
>
> But you haven't said that. You keep going back to pulleys and geegaws
> of this sort when I keep saying that they can be made mechanically
> equivalent so that they are no longer a point of difference between
> the two machines. It's like I'm saying I don't want fries with that
> and you keep asking whether I would like ketchup with my fries...are
> you really saying that the fries just come with the order regardless
> of what I want?
>
> Again, there are no pulleys, etc. involved here. Not because they
> don't exist, but because they're *mechanically equivalent* such that
> they factor one another out as differences between the two machines.
>
>> Well, that's been clear for quite a while.
>
> So why not talk to me about what I'm talking about -- since you're
> replying to me -- instead of continuing to go on about oranges to my
> apples??
>
>> I'm generalising. I thought it was obvious that the fine detail of the
>> linkage between the handles and the weights didn't matter (provided
>> there's no mechanical advantage), but i guess it's not.
>
> It's obvious it doesn't matter.
>
> There is no mechanical advantage between mechanically equivalent
> machines.
>
> You (and the others) keep bringing up mechanical advantage with
> pulleys and so forth, when I keep saying that there is no mechanical
> advantage between mechanically equivalent machines.
>
You don't get it. It has nothing to do with mechanical advantage. Every
weight machine I've ever seen results in weight moving vertically- sometimes
at an angle, but always involving an increase in height. If a machine moved
a weight horizontally the only force involved would be friction. A seated
bench press machine translates a horizontal force into a vertical force. You
need to understand that. The horizontal force won't be less than the
vertical force. Biomechanically it's different because your body is in a
different position.

On Feb 14, 7:49 pm, "ATP*" <waxwingsl...@azurepane.com> wrote:
>
>
> You don't get it. It has nothing to do with mechanical advantage.

But that's what *they* keep bringing up!

> Every
> weight machine I've ever seen results in weight moving vertically- sometimes
> at an angle, but always involving an increase in height. If a machine moved
> a weight horizontally the only force involved would be friction. A seated
> bench press machine translates a horizontal force into a vertical force. You
> need to understand that.

Yes, I think I got that part. What I'm trying to account for is why
users feel that translation as being easier to perform.

> The horizontal force won't be less than the
> vertical force. Biomechanically it's different because your body is in a
> different position.

So is this really your thesis now, then, that it's "biomechanical
advantage," and not mechanical advantage? 'Cause you all kept talking
about pulleys and levers, which means mechanics (of the machine, not
the body).

On Feb 13, 11:20 pm, "ATP*" <waxwingsl...@azurepane.com> wrote:
>
>
> A wrap over one fixed axle pulley changes the direction of the force
> applied. Aside from an almost negligible loss due to friction, that's all it
> does. The direction that the cable is pulled does not change the amount of
> force that has to be applied to lift the weight stack. If you, for example,
> take a cable from a cable crossover machine, you can change the direction of
> applied force without changing the amount of force that needs to be applied
> (with the exception of the amount of energy it takes to lift the mass of the
> cable and your arms, which is almost negligible and not what we are arguing
> about). Your biomechanics would change, but if you were pulling that cable
> with a spring scale you would see that the force applied does not. Same
> principle applies if levers are moving weight stacks or puilling cables.


Okay..."whatever" -- by which I don't mean disrespect or dismissal,
but simply that I am not the one talking about pulleys and so forth as
an explanation, so I don't know why it's an issue.

It sounds like you're now arguing with me over my statements about
"mechanical equivalence"...I only brought up mechanical equivalence
because you people were talking about pulleys...sounds like now you're
saying pulleys don't matter -- ?!

How about this: just state what your explanation is. Give a
definitive statement in your response. I don't mean that it has to be
extremely detailed; only that it's comprehensive enough to qualify as
being acceptably, generally, definitive. We can work from there.

In the meantime, I'm going to consult a physics professor and will
respond then.

"Prisoner at War" <prisoner_at_war@yahoo.com> wrote in message
news:2731a1d4-d0ea-4d70-b02b-cd857e9edaeb@e23g2000prf.googlegroups.com...
> On Feb 13, 11:20 pm, "ATP*" <waxwingsl...@azurepane.com> wrote:
>>
>>
>> A wrap over one fixed axle pulley changes the direction of the force
>> applied. Aside from an almost negligible loss due to friction, that's all
>> it
>> does. The direction that the cable is pulled does not change the amount
>> of
>> force that has to be applied to lift the weight stack. If you, for
>> example,
>> take a cable from a cable crossover machine, you can change the direction
>> of
>> applied force without changing the amount of force that needs to be
>> applied
>> (with the exception of the amount of energy it takes to lift the mass of
>> the
>> cable and your arms, which is almost negligible and not what we are
>> arguing
>> about). Your biomechanics would change, but if you were pulling that
>> cable
>> with a spring scale you would see that the force applied does not. Same
>> principle applies if levers are moving weight stacks or puilling cables.
>
>
> Okay..."whatever" -- by which I don't mean disrespect or dismissal,
> but simply that I am not the one talking about pulleys and so forth as
> an explanation, so I don't know why it's an issue.

It's an issue because something has to change the direction of the applied
horizontal force to lift the weight vertically. Usually, there is a pulley
and a cable involved.
>
> It sounds like you're now arguing with me over my statements about
> "mechanical equivalence"...I only brought up mechanical equivalence
> because you people were talking about pulleys...sounds like now you're
> saying pulleys don't matter -- ?!

Read the wikipedia article. Look at the picture of the cable over the fixed
axle pulley. There is no mechanical advantage.
>
> How about this: just state what your explanation is. Give a
> definitive statement in your response. I don't mean that it has to be
> extremely detailed; only that it's comprehensive enough to qualify as
> being acceptably, generally, definitive. We can work from there.

I really can't make it any clearer. If you want to learn, find a physics
book and work the problems. This is a subject where your feelings don't
count.
>
> In the meantime, I'm going to consult a physics professor and will
> respond then.

That would be great, except you will probably also fail to understand the
physics professor and come back with an even more convoluted explanation.

"Prisoner at War" <prisoner_at_war@yahoo.com> wrote in message
news:212548c2-ea6b-4304-b5b2-2705797c9a5f@d21g2000prf.googlegroups.com...
> On Feb 14, 7:49 pm, "ATP*" <waxwingsl...@azurepane.com> wrote:
>>
>>
>> You don't get it. It has nothing to do with mechanical advantage.
>
> But that's what *they* keep bringing up!
>
>> Every
>> weight machine I've ever seen results in weight moving vertically-
>> sometimes
>> at an angle, but always involving an increase in height. If a machine
>> moved
>> a weight horizontally the only force involved would be friction. A seated
>> bench press machine translates a horizontal force into a vertical force.
>> You
>> need to understand that.
>
> Yes, I think I got that part. What I'm trying to account for is why
> users feel that translation as being easier to perform.
>
>> The horizontal force won't be less than the
>> vertical force. Biomechanically it's different because your body is in a
>> different position.
>
> So is this really your thesis now, then, that it's "biomechanical
> advantage," and not mechanical advantage? 'Cause you all kept talking
> about pulleys and levers, which means mechanics (of the machine, not
> the body).

I'm saying that the only difference between the two setups (assuming both
have the same or no mechanical advantage) is the position of the user's
body. I doubt that would affect the ability to bench that much, but if it
seems easier, it's not because pushing forward requires inherently less
force than pushing up.

On Feb 15, 7:10 pm, "ATP*" <waxwingsl...@azurepane.com> wrote:
>
>
> It's an issue because something has to change the direction of the applied
> horizontal force to lift the weight vertically. Usually, there is a pulley
> and a cable involved.
>
> Read the wikipedia article. Look at the picture of the cable over the fixed
> axle pulley. There is no mechanical advantage.
>
> I really can't make it any clearer. If you want to learn, find a physics
> book and work the problems. This is a subject where your feelings don't
> count.

You've been doing snippets here and there, as you deem necessary,
while responding to my statements. I'm asking you to just state it
all at once, now, so we can proceed with less semantic confusion. It
seems that you do not even recognize the semantic issues involved,
issues of language use and meaning, which issues are exacerbated by an
informal discussion where assumptions are not spelled out (which is
what I'm asking of you now, in effect) and proceed piece-meal, leading
to this kind of a conversational merry-go-round.

You people do not seem to realize that you have to argue from *within*
someone else's argument...instead, you keep arguing from some
assumptions of your own -- therefore, I'm asking you for your
"definitive" explanation to this fairly common workout question.

> That would be great, except you will probably also fail to understand the
> physics professor and come back with an even more convoluted explanation.

I doubt it, because face-to-face communication has most often been
much more effective when resolving intellectual disputes for me. It's
actually very curious how much "theoretical knowledge" may be conveyed
through body language and tone of voice! I recall certain trig word
problems which had puzzled me on the page, but which discussing with a
teacher -- without him or her giving the answer -- immediately made
sense, like a zen-bomb going off!

"Prisoner at War" <prisoner_at_war@yahoo.com> wrote in message
news:05f551a0-c30d-431d-8ab3-eab1c15e725f@p73g2000hsd.googlegroups.com...
> On Feb 15, 7:10 pm, "ATP*" <waxwingsl...@azurepane.com> wrote:
>>
>>
>> It's an issue because something has to change the direction of the
>> applied
>> horizontal force to lift the weight vertically. Usually, there is a
>> pulley
>> and a cable involved.
>>
>> Read the wikipedia article. Look at the picture of the cable over the
>> fixed
>> axle pulley. There is no mechanical advantage.
>>
>> I really can't make it any clearer. If you want to learn, find a physics
>> book and work the problems. This is a subject where your feelings don't
>> count.
>
> You've been doing snippets here and there, as you deem necessary,
> while responding to my statements. I'm asking you to just state it
> all at once, now, so we can proceed with less semantic confusion. It
> seems that you do not even recognize the semantic issues involved,
> issues of language use and meaning, which issues are exacerbated by an
> informal discussion where assumptions are not spelled out (which is
> what I'm asking of you now, in effect) and proceed piece-meal, leading
> to this kind of a conversational merry-go-round.

>
> You people do not seem to realize that you have to argue from *within*
> someone else's argument...instead, you keep arguing from some
> assumptions of your own -- therefore, I'm asking you for your
> "definitive" explanation to this fairly common workout question.
>
>> That would be great, except you will probably also fail to understand the
>> physics professor and come back with an even more convoluted explanation.
>
> I doubt it, because face-to-face communication has most often been
> much more effective when resolving intellectual disputes for me. It's
> actually very curious how much "theoretical knowledge" may be conveyed
> through body language and tone of voice! I recall certain trig word
> problems which had puzzled me on the page, but which discussing with a
> teacher -- without him or her giving the answer -- immediately made
> sense, like a zen-bomb going off!

You're just in way over your head here and a discussion on usenet is not
going to clear things up for you. Get some basics under your belt and then
maybe we can have a productive conversation.