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jtelle79
10-04-1998, 05:12 PM
In a message dated 10/4/98 5:12:33 PM, you wrote:

Cardinale is using a more complex battery of tests in his analysis of
exercise

>machines.


MC--This is my problem, find a way to colect reliable data on what I am
looking at:

What happens when a subject moves a load on a (let's say) a Leg Extension with
different cammes shapes ?

And what at different speed ?

Telle --this really is your area---isnt the technology there to do this-what
about komi and Hakkinens EMG cam methodology


>-Again I am only stating that we field

>practioners often have much anecdotal “evidence?” to suggest direction !!!!

And we are here to receive your useful suggestions.

>Siff--One of the points often made against exercise machines which are

>designed to accommodate to the variation in torque with joint angle is that

>the cam or lever system does not adequately 'match' the unloaded or

>'isotonically' loaded

>joint.

>

>Telle--Im saying that it doesent even come close?? that the curves are

>typically 10-100 %? off, depending on testing mediums, measurements and

>comparison methodology/quantification.


*** I agree with both of you. In fact I am convinced by the fact that,
notwithstanding the research groups in the industrial setting, still we cannot
affirm that exercise machines equipped with a cam or a pulley or whatever else
similar are capable of match human torque capabilities.

telle--theyre not--for any given set of repetitions, human torque capabilities
change in mean force and profile every rep.


> the average speed was to fast and the set terminated to

>quickly to be usefull for gross hypertrophy--leading many cam scientists to

>reduce the speed “slomos” for increased overall hypertrophy--more fibers
under

>longer time under tension TUT--(my guess)*


*** Well, Mr Telle, Our point here is not the training effect, since, we would
open another huge discussion about this argument. The point is:

There is a weight stack to move, and it is atached to a pulley, or a cam or 3
different cam types.....what is going on in our joints or muscles ?

Telle--Well, MC, after you figure that out Ill tell you why any given cam
shape is the least effective training modality..


>-i.e. high degree of motivation(mental intensity), attempted

>maximum speed-acceleration to recruit and train the high threshold, max

>strength/(generally) power fibers at the highest possible tension and to over

>come non productive resistance curve (to much or to little resistance at

>various arcs in the movement) deficencies.


*** Again I think we missed the point. I am talking about exercise machines we
can find in a Fitness center where they can be used by the 20 years old fitnes
fun, the 25 y.o. atlete and the 50 years old average person who is willing to
improve his/her fitness status.

Telle--so you are interested in more than pure reliability?

So the point is: creating an ergonomic station on which joint and muscle
performance is optimized.

Telle--this ergonomic station already exists-------the--DUMBBELL--followed by
the BARBELL. Variations in specific torque capacities can be addressed much
easier with a dumbbell (or cable pulley unit) than with any camed machine.

>My research findings are that you positively cannot test dynamic

>strength(isometrics is useless)accurately with either inertial or speed

>controlled devices--leading me to a combination of the two as necessary.


*** Well, I am convinced by the fact that speed controlled devices cannot be
useful in determining dynamic strength accurately expecially if the goal is to
verify training adaptations, since the best way is to determine it through
testing the same exercise used in the training plan.

TELLE--Then your only testing against the training device--with any inherent
problems associated--are not strength increases a function of training and
testing modality similarities ?

Anyway, our research group use for dynamic strength testing a device capable
of measuring F,P, and V synchronized with 4 EMG called MuscleLab and developed
by Dr.Bosco (Our research director). We basicly measure displacement of the
weight pack and from there all the derived patterns. This system has been
proved to be reliable (Bosco et al. 1995)

Telle--with all due respect what good is reliability with out validity ?--lots
of modes have proven reliable!--or are you just after consistent EMG
recordings--accross differrent testing sessions--and what reliability
coefficent do you consider worthy?


>Eccentric force generating capacities are NOT a function of the preceeding

>contractted force--initial eccentric force generating capacities range from
40

>% to ?? % higher than ending concentric force. As fatigue accumulates

>contracted force will diminish to 0 while initial eccentric force can be as

>high as 80% of starting eccentric force.


*** well...sometimes looks like terminology makes things hard to understand.

Contracted force means contractile force or concentric force ?????

Please clarify this point Mr.Telle.

Telle--it SHOULD read "contracted concentric force" thanks for pointing this
out!


> I have never tested absolute

>eccentric strength

*** I do not see why we need it and how we can determine it.......


>--this still needs to be mapped9high injury potentialalready

>discussed by Siff---also for anyone interested, contracted position eccentric

>force levels effect longest position eccentric forces--with the effect

>apparently amplified by fatigue. It follows that if the longer position is
the

>more productive range to exercise(authors belief)--then maximal contracted

>eccentric force must be reduced !


*** I am sorry......but again this point is not clear to me,

TELLE --The maximal effort fatigue accumulated at the start of the eccentric
movement decreases force at the end of the eccentric movement--where more
force might be more productive!!

By the way, let me add some cents:

If we need to evaluate mechanical and neuromuscular characteristics of a Leg
Extension (i.e.) build with different cam design or pullleys, we need
absolutely to evaluate one single rep for the following reason:

1) Avoid Re-use of elastic energy

2) Avoid potentiationof neural activity following a rapid eccentric phase

both showing when performing more than 1 rep.

Possibly, we need to evaluate mainly the concentric component, since this one
is the one mostly affected my torque capabilities.

Telle--sounds purely academic at this point--how would that relate to training
over a series of repetitions--specific to any activity. ?

The study of the eccentric part would be interesting just later.c

Telle--concentric torque is, in part, a function of the eccentric--like the
horse before the cart. You CANNOT accuartely test the wide range of concentric
forces with out some eccentric lenghtening !!

Another point is:

In order to work as planned, the weights on a cam-ype machine, need to be
moved at a constant low velocity.

How can we measure reliably EMG patterns if we are asking subjects at a
constant velocity something ?

Which can be the optimal velocity for testing ?


Or......

At which speed is the function of a cam optimized ?

telle --whatever the OPTIMAL speed for a cam is --is purely wasted
academia--the cam is far less amenable to specific training adaptations then
is a free weight--unless you can vary the shape of the cam every rep--to match
the exercisers force !

For starters--try combining cams and a hydraulic device--then you can train as
hard and as fast (attempted speed) as you want and still control accel-
deceleration and speed somewhat specific to the athletes needs !


This discussion is becoming always more interesting and stimulating,

I hope there will be more and more people involved in the next days,

TELLE--me too

Jerry

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