PDA

View Full Version : Chew on this - mfw-relevant case in med. school.


Arashikage
September 19th 04, 02:55 PM
Hi, I've recently started medical school, and my group's got a case to
work on in human biology.

Here's the case basic outline:

This guy "Sebastian" wants bigger upper arms, so naturally he's doing
biceps curls to failure. When he reaches failure his training partner
helps him raise the barbell which he then lowers in a controlled
fashion. Sebastian can do 8-9 curls himself and 2-3 where he lowers
the bar.

The idea is to come up with "problems", and then produce answers to
them.

Our problems:

Will Sebastians arms grow with this routine?
Why can Sebastian lower the bar when he no longer can raise it?
At which angle (e.g 90 degrees at the elbow) will sebastian be able to
generate the most force in his curl and why?
Some **** about slow and fast-twitch muscle fibers.
The importance of nerve impulses.

Some input would be cool, especially if it conflicts what can be dug
up from the textbooks. No one in my group believed my suggestion that
fatigue of the nervous system could cause failure in lifting.

I hold a healthy skepticism towards my textbooks when it comes to
stuff like this, one of them wrote that high protein diets cause
kidney failure in healthy adults (Holum's fundamentals, 6th edition).

Dally
September 19th 04, 03:04 PM
Arashikage wrote:

> Hi, I've recently started medical school, and my group's got a case to
> work on in human biology.
>
> Here's the case basic outline:
>
> This guy "Sebastian" wants bigger upper arms, so naturally he's doing
> biceps curls to failure. When he reaches failure his training partner
> helps him raise the barbell which he then lowers in a controlled
> fashion. Sebastian can do 8-9 curls himself and 2-3 where he lowers
> the bar.
>
> The idea is to come up with "problems", and then produce answers to
> them.
>
> Our problems:
>
> Will Sebastians arms grow with this routine?

Does Sebastian follow this routine up with a 9 mile jog and then eat a
piece of sweet bread for dinner?

It seems to me that your problem puts too much emphasis on the way the
muscle is worked (it's worked, it's worked already!) and not enough on
how the muscle recovers.

Dally

spodosaurus
September 19th 04, 03:51 PM
Arashikage wrote:
> Hi, I've recently started medical school, and my group's got a case to
> work on in human biology.
>
> Here's the case basic outline:
>
> This guy "Sebastian" wants bigger upper arms, so naturally he's doing
> biceps curls to failure. When he reaches failure his training partner
> helps him raise the barbell which he then lowers in a controlled
> fashion. Sebastian can do 8-9 curls himself and 2-3 where he lowers
> the bar.
>
> The idea is to come up with "problems", and then produce answers to
> them.
>
> Our problems:
>
> Will Sebastians arms grow with this routine?

Not nearly enough information.

> Why can Sebastian lower the bar when he no longer can raise it?

The simplistic answer is because muscle are 'stronger' during eccentric
contraction than concentric contraction. IIRC, this is more than just
physics: To raise a weight, you need to overcome the accelleration due
to gravity just to hold the weight still, and then add more force to
accelerate it upwards (please feel free to write out the equations and
use the proper terms, I'm just being lazy right now). with an eccentric
contraction, all you have to do is overcome a fraction of the
acceleration due to gravity. Gravity still pulls the weight down. I'm
sure if Lyle feels like helping you do your homework he could tell you
exactly why in terms of actin and myosin.

> At which angle (e.g 90 degrees at the elbow) will sebastian be able to
> generate the most force in his curl and why?

Well, that depends on several factors, as well as interpretation of the
question. Muscles aren't equally strong from full stretch to full
contraction. Muscles are weakest at the extremes. This does not take
into account the lever arms about the joints, only the properties of
skeletal muscle. I assume, based on the wording of the question, that
lever arms can be ignored and only the contractile strength of the
muscle taken in isolation. In this case, I must say I don't know
exactly: just somewhere in between the full stretch and full contraction
positions.

> Some **** about slow and fast-twitch muscle fibers.
> The importance of nerve impulses.
>
> Some input would be cool, especially if it conflicts what can be dug
> up from the textbooks. No one in my group believed my suggestion that
> fatigue of the nervous system could cause failure in lifting.
>

That's not the answer that's being looked for. And IMO does not apply to
one set of curls taken in isolation.

> I hold a healthy skepticism towards my textbooks when it comes to
> stuff like this, one of them wrote that high protein diets cause
> kidney failure in healthy adults (Holum's fundamentals, 6th edition).


--
To send me an email, try my handle at yahoo.com

MJL
September 19th 04, 08:17 PM
On 19 Sep 2004 06:55:56 -0700, (Arashikage)
wrote:

>Hi, I've recently started medical school, and my group's got a case to
>work on in human biology.
>
>Here's the case basic outline:
>
>This guy "Sebastian" wants bigger upper arms, so naturally he's doing
>biceps curls to failure. When he reaches failure his training partner
>helps him raise the barbell which he then lowers in a controlled
>fashion. Sebastian can do 8-9 curls himself and 2-3 where he lowers
>the bar.
>
>The idea is to come up with "problems", and then produce answers to
>them.
>
>Our problems:
>
>Will Sebastians arms grow with this routine?

Caloric balance?

Frequency of training?

General health?

Trained or untrained?

Medications?

General lifestyle info?

Any one of these could ensure he would not hypertrophy.

>Why can Sebastian lower the bar when he no longer can raise it?

Textbook stuff.

>At which angle (e.g 90 degrees at the elbow) will sebastian be able to
>generate the most force in his curl and why?

force = mass * acceleration

In a theoretical sense the place he'd be able to generate the most
force is at 180 degrees just before the weight pulls his shoulder out
of its socket. Perhaps obvious but if the question if phrased as
simply where COULD he generate the most force, I believe that is the
correct answer.

Are you sure the question does not ask where force is the greatest in
the concentric phase of the lift? That would make more sense.

>Some **** about slow and fast-twitch muscle fibers.
>The importance of nerve impulses.
>

Textbook stuff.


--
http://www.texansfortruth.org/

Proton Soup
September 19th 04, 08:56 PM
On 19 Sep 2004 06:55:56 -0700, (Arashikage)
wrote:

>Hi, I've recently started medical school, and my group's got a case to
>work on in human biology.
>
>Here's the case basic outline:
>
>This guy "Sebastian" wants bigger upper arms, so naturally he's doing
>biceps curls to failure. When he reaches failure his training partner
>helps him raise the barbell which he then lowers in a controlled
>fashion. Sebastian can do 8-9 curls himself and 2-3 where he lowers
>the bar.
>
>The idea is to come up with "problems", and then produce answers to
>them.
>
>Our problems:
>
>Will Sebastians arms grow with this routine?
>Why can Sebastian lower the bar when he no longer can raise it?
>At which angle (e.g 90 degrees at the elbow) will sebastian be able to
>generate the most force in his curl and why?
>Some **** about slow and fast-twitch muscle fibers.
>The importance of nerve impulses.

The real answer is that his training method is retarded.

>Some input would be cool, especially if it conflicts what can be dug
>up from the textbooks. No one in my group believed my suggestion that
>fatigue of the nervous system could cause failure in lifting.

Hook them up to an electromyo stim device and see how many reps they
get after reaching failure on their own.

>I hold a healthy skepticism towards my textbooks when it comes to
>stuff like this, one of them wrote that high protein diets cause
>kidney failure in healthy adults (Holum's fundamentals, 6th edition).

It must be true, then.

-----------
Proton Soup

"Homo sapiens non urinat in ventum."

Lordy
September 19th 04, 11:20 PM
(Arashikage) wrote in
om:

> The idea is to come up with "problems", and then produce answers to
> them.
>
> Our problems:
>
> Will Sebastians arms grow with this routine?


> Why can Sebastian lower the bar when he no longer can raise it?
Is that a biology problem of physics?


> At which angle (e.g 90 degrees at the elbow) will sebastian be able to
> generate the most force in his curl and why?
> Some **** about slow and fast-twitch muscle fibers.
> The importance of nerve impulses.

From a biology perspective how about "risk of injury" as a problem and
generally addressing the pros can cons of training to failure ?


--
Lordy

Jeff Finlayson
September 20th 04, 04:00 PM
Arashikage wrote:

> Hi, I've recently started medical school, and my group's got a case to
> work on in human biology.
>
> Here's the case basic outline:
> This guy "Sebastian" wants bigger upper arms, so naturally he's doing
> biceps curls to failure. When he reaches failure his training partner
> helps him raise the barbell which he then lowers in a controlled
> fashion. Sebastian can do 8-9 curls himself and 2-3 where he lowers
> the bar.
>
> The idea is to come up with "problems", and then produce answers to
> them.
>
> Our problems:
> Will Sebastians arms grow with this routine?

Depends on diet. Not enough info on the routine as well.

> Why can Sebastian lower the bar when he no longer can raise it?

Less work to lower weight. Gravity helps when lowering.

> At which angle (e.g 90 degrees at the elbow) will sebastian be able to
> generate the most force in his curl and why?

90 deg. That's the point of the largest moment on the elbow,
i.e. longest lever arm.

Donovan Rebbechi
September 20th 04, 04:51 PM
On 2004-09-19, Arashikage > wrote:

> Why can Sebastian lower the bar when he no longer can raise it?

To raise it, he needs to be able to exert a force greater than the
weight to accelerate the bar at the bottom of the movement, and after
that, a force no less than the weight, to maintain speed.

When lowering it, he only needs to exert enough force to keep the
bar from accelerating too quickly (slightly less than the weight of
the bar). At the bottom of the movement, the extension of the arms
prevents the weight from continuing downward, and the padding on the
preacher bench, combined with a slight forward movement of the shoulders
prevents the elbow joint hyperextending. With a standing curl, either
the bar rests against the legs at the bottom, or with dumbells, the
shoulder joint helps bring the weight to a stop at the bottom.

Cheers,
--
Donovan Rebbechi
http://pegasus.rutgers.edu/~elflord/

Jim Ranieri
September 20th 04, 06:19 PM
"Jeff Finlayson" > wrote in message


> > At which angle (e.g 90 degrees at the elbow) will sebastian be able to
> > generate the most force in his curl and why?
>
> 90 deg. That's the point of the largest moment on the elbow,
> i.e. longest lever arm.
>

Hmmm, that's the engineering answer - but I wonder if more force is capable
of being generated inside the muscle when it is shortened - bringing more
actin / myosin sites into contact with one another as the filaments slide. I
dunno.

Jeff Finlayson
September 20th 04, 07:10 PM
Jim Ranieri wrote:
> Jeff Finlayson wrote:
>
>>>At which angle (e.g 90 degrees at the elbow) will sebastian be able to
>>>generate the most force in his curl and why?
>>
>>90 deg. That's the point of the largest moment on the elbow,
>>i.e. longest [effective] lever arm.
>
> Hmmm, that's the engineering answer - but I wonder if more force is capable
> of being generated inside the muscle when it is shortened - bringing more
> actin / myosin sites into contact with one another as the filaments slide. I
> dunno.

Fair point.
I thought of the question more as 'At which angle will sebastian HAVE
to generate the most force in his curl and why?'.

Lyle McDonald
September 20th 04, 08:07 PM
Jim Ranieri wrote:

> "Jeff Finlayson" > wrote in message
>
>
>
>>>At which angle (e.g 90 degrees at the elbow) will sebastian be able to
>>>generate the most force in his curl and why?
>>
>>90 deg. That's the point of the largest moment on the elbow,
>>i.e. longest lever arm.
>>
>
>
> Hmmm, that's the engineering answer - but I wonder if more force is capable
> of being generated inside the muscle when it is shortened - bringing more
> actin / myosin sites into contact with one another as the filaments slide. I
> dunno.

Maximum force production capacity of the muscle doesn't occur at the
longest or shortest muscle length. rather, muscles have an optimum
length-tension relationship outside of which force production falls off.
So at extreme lengths, force production is decreased because of
lowered cross-bridging of the individual filaments (actin and myosin)
and at extreme shortening, you end up with the same end results (less
cross bridging) but because the muscle is sort 'bunched up' against itself.

Of course, that interacts with the changing mechanics of the movement.
With the exception of devices which adjust force requirements, every
movement has a point where the force production requirements are
highest. This occurs at the 90 degree point for a standard curl for the
reasons stated below.

Lyle

Jim Ranieri
September 20th 04, 09:48 PM
"Lyle McDonald" > wrote in message
...
> Jim Ranieri wrote:
>
> > "Jeff Finlayson" > wrote in message
> >
> >
> >
> >>>At which angle (e.g 90 degrees at the elbow) will sebastian be able to
> >>>generate the most force in his curl and why?
> >>
> >>90 deg. That's the point of the largest moment on the elbow,
> >>i.e. longest lever arm.
> >>
> >
> >
> > Hmmm, that's the engineering answer - but I wonder if more force is
capable
> > of being generated inside the muscle when it is shortened - bringing
more
> > actin / myosin sites into contact with one another as the filaments
slide. I
> > dunno.
>
> Maximum force production capacity of the muscle doesn't occur at the
> longest or shortest muscle length. rather, muscles have an optimum
> length-tension relationship outside of which force production falls off.
> So at extreme lengths, force production is decreased because of
> lowered cross-bridging of the individual filaments (actin and myosin)
> and at extreme shortening, you end up with the same end results (less
> cross bridging) but because the muscle is sort 'bunched up' against
itself.
>

Ah. I forgot about the bunched up filament phenomenon.

> Of course, that interacts with the changing mechanics of the movement.
> With the exception of devices which adjust force requirements, every
> movement has a point where the force production requirements are
> highest. This occurs at the 90 degree point for a standard curl for the
> reasons stated below.
>

So the force generating capacity of the muscle may be optimal around
mid-contraction, which would roughly correspond with the max force
requirement due to the mechanics of the movement but since the sticking
point of the movement is right around 90 (at least for me) that means that
the max force generating capacity differential is not as great as...ah, who
the hell cares

MJL
September 21st 04, 03:31 AM
On Sun, 19 Sep 2004 19:17:38 GMT, MJL > wrote:

>On 19 Sep 2004 06:55:56 -0700, (Arashikage)
>wrote:
>
>>Hi, I've recently started medical school, and my group's got a case to
>>work on in human biology.
>>
>>Here's the case basic outline:
>>
>>This guy "Sebastian" wants bigger upper arms, so naturally he's doing
>>biceps curls to failure. When he reaches failure his training partner
>>helps him raise the barbell which he then lowers in a controlled
>>fashion. Sebastian can do 8-9 curls himself and 2-3 where he lowers
>>the bar.
>>
>>The idea is to come up with "problems", and then produce answers to
>>them.
>>
>>Our problems:
>>
>>Will Sebastians arms grow with this routine?
>
>Caloric balance?
>
>Frequency of training?
>
>General health?
>
>Trained or untrained?
>
>Medications?
>
>General lifestyle info?
>
>Any one of these could ensure he would not hypertrophy.
>
>>Why can Sebastian lower the bar when he no longer can raise it?
>
>Textbook stuff.
>
>>At which angle (e.g 90 degrees at the elbow) will sebastian be able to
>>generate the most force in his curl and why?
>
>force = mass * acceleration
>
>In a theoretical sense the place he'd be able to generate the most
>force is at 180 degrees just before the weight pulls his shoulder out
>of its socket. Perhaps obvious but if the question if phrased as
>simply where COULD he generate the most force, I believe that is the
>correct answer.

Then again that may not be where he could accelerate it the most. It
may be at the top of the movement.

Or what lyle said (I always overthink stuff).


--
http://www.texansfortruth.org/

Seth Breidbart
September 22nd 04, 02:04 AM
In article >,
Donovan Rebbechi > wrote:
>On 2004-09-19, Arashikage > wrote:
>
>> Why can Sebastian lower the bar when he no longer can raise it?
>
>To raise it, he needs to be able to exert a force greater than the
>weight to accelerate the bar at the bottom of the movement, and after
>that, a force no less than the weight, to maintain speed.
>
>When lowering it, he only needs to exert enough force to keep the
>bar from accelerating too quickly (slightly less than the weight of
>the bar).

That difference (maybe 5-10%, or less) is much less than the
difference between concentric strength (the max you can lift) and
eccentric strength (the max you can lower under control).

Try again.

Seth
--
Who cares? Shut up and lift. -- Watson (the pencil neck) Davis

Donovan Rebbechi
September 22nd 04, 04:50 PM
On 2004-09-22, Seth Breidbart > wrote:
> In article >,
> Donovan Rebbechi > wrote:
>>On 2004-09-19, Arashikage > wrote:
>>
>>> Why can Sebastian lower the bar when he no longer can raise it?
>>
>>To raise it, he needs to be able to exert a force greater than the
>>weight to accelerate the bar at the bottom of the movement, and after
>>that, a force no less than the weight, to maintain speed.
>>
>>When lowering it, he only needs to exert enough force to keep the
>>bar from accelerating too quickly (slightly less than the weight of
>>the bar).
>
> That difference (maybe 5-10%, or less) is much less than the
> difference between concentric strength (the max you can lift) and
> eccentric strength (the max you can lower under control).
>
> Try again.

Internal muscular friction ?

Just a guess.
--
Donovan Rebbechi
http://pegasus.rutgers.edu/~elflord/

Lyle McDonald
September 22nd 04, 07:09 PM
Donovan Rebbechi wrote:

> On 2004-09-22, Seth Breidbart > wrote:
>
>>In article >,
>>Donovan Rebbechi > wrote:
>>
>>>On 2004-09-19, Arashikage > wrote:
>>>
>>>
>>>>Why can Sebastian lower the bar when he no longer can raise it?
>>>
>>>To raise it, he needs to be able to exert a force greater than the
>>>weight to accelerate the bar at the bottom of the movement, and after
>>>that, a force no less than the weight, to maintain speed.
>>>
>>>When lowering it, he only needs to exert enough force to keep the
>>>bar from accelerating too quickly (slightly less than the weight of
>>>the bar).
>>
>>That difference (maybe 5-10%, or less) is much less than the
>>difference between concentric strength (the max you can lift) and
>>eccentric strength (the max you can lower under control).
>>
>>Try again.
>
>
> Internal muscular friction ?
>
> Just a guess.

Only if you are a Superslow Cultist.

But internal muscular friction can't even begin to account for the
difference in max concentric and eccentric strength.

Most likely a combination of neural factors, differences in fiber
recruitment (preferentialy Type II recruitment) and differences in ATP
utilization (much more efficient in eccentrics).

Lyle

Adam Becker Sr
October 18th 04, 03:28 PM
Proton Soup > wrote in message >...

> >This guy "Sebastian" wants bigger upper arms, so naturally he's doing
> >biceps curls to failure.

> The real answer is that his training method is retarded.

OK, I'm a newbie. I'll bite. Is there a good FAQ or something around
here that addresses doing curls to failure vs some other method?

What are the top things that this question doesn't address that will
make the most difference in whether Sebastian gets big upper arms.

Adam Becker