At 04.03 04/10/98 EDT, you wrote:

Well...looks like my little stone in the lake is creating some useful discussions on the biomechanical aspects of exercise machines.

Let's add a bit of info on the last email of Mr.Telle and the indications of Dr..Siff

>Telle--Im not so sure about all of this, I do not mean in any way to suggest

>my techniques be “ the sole analytical method for assessing the efficacy of a

>specific training modality”. --admittedly my knowledge of EMG

>qunatification is below expert--but my knowledge of biomechanics and “eyeball”

>skills are enough to project further direction by more quantifiably qualified

>individuals--if they have someone like Us, Chek, Poliquin, or Goldenburg or

>others I am unaware of to assist in exercise technique control.

Well...Mr.Telle took something personally as it comes out from his email. By the way let me add some comments to this.

Here we are not discussing about which one is the right technique, we are discussing on how it can be possible to make less errors ?

Moreover, with all the respect I have for Chek, Poliquin, or Goldenburg....It does not seem to me they are World Renowed their help is important from a coaching stendpoint and in Exercise Principles, I think.

>emerge from deeper computer analysis, so this is undoubtedly why Prof

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


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 ?

>-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



>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.

> 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 ?

>-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.

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

>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.

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)

>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.

> 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,

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.

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

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 ?


At which speed is the function of a cam optimized ?

This discussion is becoming always more interesting and stimulating,

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

Marco Cardinale


Marco Cardinale, M.S.S.

Associate Editor Coaching & Sport Science Journal




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