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TELLE ORIGINAL STATEMENT>My dynamic strength curve findings ALL indicate that
strength curves/profiles
>change ever rep! ---bottom line is--single profile cams cant and never will
provide resistance matching the athletes changing force expressions!! (unless
your doing just one rep and even at that the speed as a function of the
loading pattern manifests different curves----with ~ the same area underneath
same!!
SIFF RESPONSE--BIOMECHANICAL ASSESSMENT
This generally is true of all biomechanical measurements in sport, including
force plate, high speed video and EMG methods, but is does not imply that the
information from single recordings is useless or misleading.
Telle--There’s no insinuation that the information, in general, is useless but
it CAN be misleading--in this age of; specific loading and rates of
acceleration-speed-deceleration patterns-- any generalized loading pattern is
quite POTENTIALLY not as facilitative as an other. The single recording
information IS useless when projecting the shape of a cam ostensibly profiled
to maintain a resistance commenserate with user force.
-----------------------
SIFF---This is why time
averaged series of recordings and spectral analytical techniques are also
used,
TELLE---”time averaged series of recordings and spectral analytical
techniques”---of one loading pattern only give you a generalized (Mean?)
specttra of that single pattern..If one were to average different force
loading patterns, that might occur during any single rep stength analysis,
into one quantification--all the representaitve loadings would, to some
degree, be basterdized..
-----------------------------
Siff ---.Superficial EMGs are notoriously difficult to record with consistent
accuracy and reproducibility
Telle--Reliability has always been high on my EMG tests
Siff---or to interpret without vast experience in the field, so
one cannot rely on these as the sole analytical method for assessing the
efficacy of a specific training modality.
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.
Siff--'Eyeballing' of EMG printouts can often misinterpret or miss trends
which
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
machines.
Telle--couldnt agree more--I am familiar with and have used the PDS
function--but am sure Prof Cardinales knowledge and equipment would manifest a
much greater validity factor--Again I am only stating that we field
practioners often have much anecdotal “evidence?” to suggest direction !!!!
------------------------------
MATCHING OF TORQUE CURVES
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.
Siff---the counter argument usually remarks that, with free weights, the
individual can at least accelerate or decelerate the external load to
compensate for changes in joint torque characteristics (sometimes called
'Compensatory Acceleration').
Telle--this ingeneous CAT “Compensatory Acceleration” Hatfield concept can be
used with inertial resistance on any platform--especially movement
guided--FIXED VARIABLE RESISTANCE machines--pointedly its about all that saved
the early cam equipment from being more ineffective then they were--e.g. if
the weight was concentrically accelerated fast enough--the resulting kinetic
energy carried the weight through the final stages of the cam exagerated con
movement with the addition of the “right”? amount of user
force--unfortuanately 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)*
Siff--However, this 'compensatory acceleration' method can also be applied
during
exercise on any non-isokinetic, centrifugal clutch or feedback-controlled
exercise machine,--------
TELLE---Maybe I need this clarified--is not ”compensatory acceleration” an
inertial (weights--free or guided) only technique--or am I’m just splitting
fibers???--as the same general intent is expressed with both testing/training
modalities----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.
Further more since (Siff) -----‘compensatory acceleration' method(s) can also
be applied during exercise on any non-isokinetic, centrifugal clutch or
feedback-controlled exercise machine,------arguments about (the) matching of
individual 'strength curves' to 'machine curves' of cam and lever based
machines are not that simple.
Telle--Again Im not sure what the intent is here. First of all the concept of
a ”basic strength curve” or even any usefull approximation of same, is without
merit.
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.
Inertial resistance for the E-I-C (eccentric-isometric-concentric) transition
and initial acceleration segments and a speed device to control kinetic
energy/momentum throughout the remainder of the rep to near full
contraction--at that point, reapplyinng inertial resistance--or reducing speed
to the end (the end measurements are more speculation then fact--regardless
the first 90-95% of the concentric movement can be accurately measured
dynamically !!
Concentric force generating capacities and fiber contractile contributions
vary greatly as a function of eccentric to isometric loading parameters,
e.g. weight, speed, displacement, rates of deceleraton, time at the isometric
position and rates of concen-acceleration
Artifical resistance machines cannot duplicate all the characteristics of an
inertial mass--necesary to derive accurate E-I-C force profiles.
Eccentric measurements are somewhat “easier”? due to C-E (concentric to
eccentric) movement transition resistance requirements being not as
restrictive as the E-I-C transition requirements.
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.
Eccentric testing requiremnts include a slow build up, 1-2 sec ?., of
resistance at the contracted position--with limbs slightly unlocked for closed
chain exercises. Resistance is supplied inertially, hydraulically manually or
a combination of the 3 as a function of speed. I have never tested absolute
eccentric strength--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 !
Jerry
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strength curves/profiles
>change ever rep! ---bottom line is--single profile cams cant and never will
provide resistance matching the athletes changing force expressions!! (unless
your doing just one rep and even at that the speed as a function of the
loading pattern manifests different curves----with ~ the same area underneath
same!!
SIFF RESPONSE--BIOMECHANICAL ASSESSMENT
This generally is true of all biomechanical measurements in sport, including
force plate, high speed video and EMG methods, but is does not imply that the
information from single recordings is useless or misleading.
Telle--There’s no insinuation that the information, in general, is useless but
it CAN be misleading--in this age of; specific loading and rates of
acceleration-speed-deceleration patterns-- any generalized loading pattern is
quite POTENTIALLY not as facilitative as an other. The single recording
information IS useless when projecting the shape of a cam ostensibly profiled
to maintain a resistance commenserate with user force.
-----------------------
SIFF---This is why time
averaged series of recordings and spectral analytical techniques are also
used,
TELLE---”time averaged series of recordings and spectral analytical
techniques”---of one loading pattern only give you a generalized (Mean?)
specttra of that single pattern..If one were to average different force
loading patterns, that might occur during any single rep stength analysis,
into one quantification--all the representaitve loadings would, to some
degree, be basterdized..
-----------------------------
Siff ---.Superficial EMGs are notoriously difficult to record with consistent
accuracy and reproducibility
Telle--Reliability has always been high on my EMG tests
Siff---or to interpret without vast experience in the field, so
one cannot rely on these as the sole analytical method for assessing the
efficacy of a specific training modality.
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.
Siff--'Eyeballing' of EMG printouts can often misinterpret or miss trends
which
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
machines.
Telle--couldnt agree more--I am familiar with and have used the PDS
function--but am sure Prof Cardinales knowledge and equipment would manifest a
much greater validity factor--Again I am only stating that we field
practioners often have much anecdotal “evidence?” to suggest direction !!!!
------------------------------
MATCHING OF TORQUE CURVES
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.
Siff---the counter argument usually remarks that, with free weights, the
individual can at least accelerate or decelerate the external load to
compensate for changes in joint torque characteristics (sometimes called
'Compensatory Acceleration').
Telle--this ingeneous CAT “Compensatory Acceleration” Hatfield concept can be
used with inertial resistance on any platform--especially movement
guided--FIXED VARIABLE RESISTANCE machines--pointedly its about all that saved
the early cam equipment from being more ineffective then they were--e.g. if
the weight was concentrically accelerated fast enough--the resulting kinetic
energy carried the weight through the final stages of the cam exagerated con
movement with the addition of the “right”? amount of user
force--unfortuanately 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)*
Siff--However, this 'compensatory acceleration' method can also be applied
during
exercise on any non-isokinetic, centrifugal clutch or feedback-controlled
exercise machine,--------
TELLE---Maybe I need this clarified--is not ”compensatory acceleration” an
inertial (weights--free or guided) only technique--or am I’m just splitting
fibers???--as the same general intent is expressed with both testing/training
modalities----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.
Further more since (Siff) -----‘compensatory acceleration' method(s) can also
be applied during exercise on any non-isokinetic, centrifugal clutch or
feedback-controlled exercise machine,------arguments about (the) matching of
individual 'strength curves' to 'machine curves' of cam and lever based
machines are not that simple.
Telle--Again Im not sure what the intent is here. First of all the concept of
a ”basic strength curve” or even any usefull approximation of same, is without
merit.
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.
Inertial resistance for the E-I-C (eccentric-isometric-concentric) transition
and initial acceleration segments and a speed device to control kinetic
energy/momentum throughout the remainder of the rep to near full
contraction--at that point, reapplyinng inertial resistance--or reducing speed
to the end (the end measurements are more speculation then fact--regardless
the first 90-95% of the concentric movement can be accurately measured
dynamically !!
Concentric force generating capacities and fiber contractile contributions
vary greatly as a function of eccentric to isometric loading parameters,
e.g. weight, speed, displacement, rates of deceleraton, time at the isometric
position and rates of concen-acceleration
Artifical resistance machines cannot duplicate all the characteristics of an
inertial mass--necesary to derive accurate E-I-C force profiles.
Eccentric measurements are somewhat “easier”? due to C-E (concentric to
eccentric) movement transition resistance requirements being not as
restrictive as the E-I-C transition requirements.
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.
Eccentric testing requiremnts include a slow build up, 1-2 sec ?., of
resistance at the contracted position--with limbs slightly unlocked for closed
chain exercises. Resistance is supplied inertially, hydraulically manually or
a combination of the 3 as a function of speed. I have never tested absolute
eccentric strength--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 !
Jerry
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For information and archives: http://www.bme.ccf.org/isb/biomch-l
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