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Dear subscribers
here's the responses I got regarding time/force relation for thixotropy of
fascia.
My question was:
Could somebody help me in finding some research figures or formulas about the
time/force needed for mechanical outside pressure needed in dense human fascia
to result in a plasticity deformation?
I am not a biomech.scientist, but a practitioner of a method of deep
tissue manipulation called 'Rolfing'. Since a few years there is now a debate
going on in my school about whether thixotropy (tissue aggregate change from gel
to sol in response to mechanical pressure) is still a valid explanatory model
for the effect of myofascial release work. The amount of time and force for one
stroke in this work is rarely more than 1 min. with 20 kg max., yet often a
tissue release is already clearly felt or at least claimed. My personal
explanation of this work favors more a neuromuscular stimulation of the Golgi
Tendon Organs in the fascial envelopes. This seems to be supported by my
experience that this technique does not work anymore under local anesthesia,
plus by the verbal report by a colleague of mine who said that he once saw a
mathematical calculation which showed that one would need to apply several tons
(!) of pressure in order to achieve such a fast plasticity change in dense human
connective tissue.
I have been trying now to find such a formula myself in the literature
in order to check the validity of this claim, yet so far without success (Except
for getting overwhelmed by the hundreds of formulas in a book by Fung, Y.C
(Biomechanics, Mechanical Properties of Living Tissues, 1981). I believe that
clarity on this question could have an influence on probably 10 000 PT and other
practitioners who practice myofascial work worldwide. Could someone of you
professionals help us further?
Robert Schleip, Munich/Germany 100326.3427@compuserve.com
(Besides to BIOMCH-L, an almost identical text was posted to two other
listserves called PHYSIO and BODYWORK. All responses are listed below.
Feel free to add more if you have additional information or hints.)
---------------------------------------------------------------------------------
I don't believe human tissues deform plastically, without injury. Additionally
I do not believe there is a sol/gel transformation in most tissues, with
the only known possibility of such a transformation to occur in mucus 9but
that's not a tissue.
Check out the Handbook of Bioengineering and read about some of the
engineering terminology and concepts, I suggest.
Douglas Chang e-mail:dchang@sdcc3.ucsd.edu
---------------------------------------------------------------------------------
From: keg@strathspey.llnl.gov (Keith Grant)
I don't know if any of the articles/abstracts below could help you. They
are pretty much what I could come up with by doing a brief medline
search.
1. Levinson SF; Shinagawa M; Sato T.
Sonoelastic determination of human skeletal muscle elasticity.
Journal of Biomechanics, 1995 Oct, 28(10):1145-54. (UI: 96074869)
Abstract: It is not currently practical to directly measure viscoelastic
parameters in human muscles in situ. Methods used in vitro cannot readily
be applied, and motion analysis provides only a gross estimate. We report
on the application of a hybrid approach, sonoelastography, which uses
ultrasound to measure the propagation of shear waves induced by externally
applied vibrations. Because shear waves predominate in incompressible
viscoelastic media at low frequencies, sonoelastic data should be
comparable to those obtained using conventional means. We recorded
vibration propagation speeds as a function of applied load in the
quadriceps muscles of ten volunteers as they underwent a series of static
contractions. Data collection during dynamic contractions, not possible
with the current equipment, will be the subject of future experimentation.
Although statistically significant correlations were not uniformly obtained
above 60 Hz nor for propagation perpendicular to the muscle fibers, this is
felt to have resulted from deviations from the applied plane wave model.
Calculated values of Young's modulus for 30 Hz propagation parallel to the
muscle fibers were 7 +/- 3, 29 +/- 12 and 57 +/- 37 x 10(3) Nm-2 for
applied loads of 0, 7.5 and 15 kg, respectively. The corresponding values
at 60 Hz were 25 +/- 6, 75 +/- 61 and 127 +/- 65. These values were
statistically significant and linearly correlated with the applied load, as
expected. Our data represent the first in situ human measurements of their
kind. It is anticipated that sonoelastography will provide a useful adjunct
to the study of human biomechanics.
2. Roleveld K; Baratta RV; Solomonow M; Huijing PA.
Role of the tendon in the dynamic performance of three different
load-moving muscles. Annals of Biomedical Engineering, 1994 Nov-Dec,
22(6):682-91. (UI: 95177434)
Abstract: The effect of the tendon's viscoelastic properties on the dynamic
performance of three different load-moving muscles was determined. The
frequency response models of the cat's medial gastrocnemius (MG), extensor
digitorum longus (EDL), and tibialis anterior (TA) with and without their
tendons were derived under sinusoidal shortening-lengthening, manipulated
by orderly recruitment and derecruitment of motor units together with
firing rate increase and decrease. The passive load sizes applied to the
muscles were approximately 30%-40% of each muscle's maximal isometric
force. It was shown that the tendon has a moderate effect on the dynamic
response of muscles while moving loads of fixed mass. The MG and EDL
without their tendons show a decrease in high frequency gain (2-5 dB) and
increasing phase lag angles (7 degrees-9 degrees). In contrast, the TA
without its tendon shows an increase in high frequency gain (2 dB) and
decreasing phase lag angles (20 degrees) compared with the same muscle with
the tendon. It was concluded that tendon's viscoelastic properties have a
moderate effect during load-moving contractions, influencing the dynamic
performance of different muscles in a different manner.
3. Johnson GA; Tramaglini DM; Levine RE; Ohno K; Choi NY; Woo SL.
Tensile and viscoelastic properties of human patellar tendon.
Journal of Orthopaedic Research, 1994 Nov, 12(6):796-803. (UI:95074703)
Abstract: The tensile and viscoelastic properties of fresh-frozen,
nonirradiated human patellar tendon were investigated in two groups of 15
specimens: one group was from individuals 29-50 years old and the other
group was from individuals 64-93 years old. The central portion of each
patella-patellar tendon-tibia complex was subjected to cyclic
preconditioning, stress-relaxation, cyclic stress-relaxation, and load to
failure tests. For each age group, stress-relaxation and stress-strain
curves were obtained, from which percentage relaxation, ultimate tensile
strength, strain at failure, modulus, and strain energy density were
determined. Viscoelastic behavior was described with use of quasilinear
viscoelasticity. The younger group showed a 46 +/- 9% (mean +/- SD)
decrease in stress after 15 minutes, whereas the older group exhibited a 50
+/- 6% decrease. The values for ultimate tensile strength and strain at
failure, respectively, were 64.7 +/- 15.0 MPa and 14 +/- 6% for the younger
group and 53.6 +/- 10.0 MPa and 15 +/- 5% for the older group. Modulus
values were 660 +/- 266 MPa for the younger group and 504 +/- 222 MPa for
the older group. Except for ultimate tensile strength, which was 17% less
for the older group than for the younger one, no statistically significant
differences were found in tensile or viscoelastic properties. This study
indicated that there were minimal differences in biomechanical properties
of the substance of the patellar tendon between younger and older age
groups.
4. Best TM; McElhaney J; Garrett WE Jr; Myers BS.
Characterization of the passive responses of live skeletal muscle using
the quasi-linear theory of viscoelasticity.
Journal of Biomechanics, 1994 Apr, 27(4):413-9. (UI: 94245766)
Abstract: The tensile viscoelastic responses of live, innervated rabbit
skeletal muscle were measured and characterized using the quasi-linear
model of viscoelasticity. The tibialis anterior (TA) and extensor digitorum
longus (EDL) muscles of anesthetized New Zealand white rabbits were
surgically exposed and tested under in vivo conditions. Rate sensitivity of
the force-time history was observed in response to constant velocity
testing at rates from 0.01 to 2.0 Hz. Average hysteresis energy, expressed
as a percentage of maximum stored strain energy, was 39.3 +/- 5.4% and was
insensitive to deformation rate. The quasi-linear model, with constants
derived from relaxation testing, was able to describe and predict these
responses with correlation exceeding the 99% confidence interval for the
132 constant velocity tests performed (rmean = 0.9263 +/- 0.0373). The
predictive ability of this model was improved when compressive loading
effects on the muscle were neglected, rmean = 0.9306 +/- 0.0324. The rate
insensitivity of hysteresis energy was predicted by the model; however, the
absolute value of the hysteresis was underestimated (30.2 +/- 4.0%). Both
muscles demonstrated strikingly different elastic functions. Geometric
normalization of these responses (stress and strain) did not result in a
single elastic function capable of describing both muscles. Based on these
results, the quasi-linear model is recommended for the characterization of
the structural responses of muscle; however, further investigation is
required to determine the influence of muscle geometry and fiber
architecture on the elastic function.
5. De Winkel ME; Blange T; Treijtel BW.
High frequency characteristics of elasticity of skeletal muscle fibres
kept in relaxed and rigor state. Journal of Muscle Research and Cell
Motility, 1994 Apr, 15(2):130-44. (UI: 94327800)
Abstract: The viscoelastic properties of crossbridges in rigor state are
studied by means of application of small length changes, completed within
30 microseconds, to isometric skinned fibre segments of the iliofibularis
muscle of the frog in relaxed and rigor state and measurement of the
tension response. Results are expressed as a complex Young's modulus, the
real part of which denotes normalized stiffness, while the imaginary part
denotes normalized viscous mechanical impedance. Young's modulus was
examined over a wide frequency range varying from 5 Hz up to 50 kHz.
Young's modulus can be interpreted in terms of stiffness and viscous
friction of the half-sarcomere or in terms of elastic changes in tension
and recovery upon a step length change. The viscoelastic properties of
half-sarcomeres of muscle fibre segments in rigor state showed strong
resemblance to those of activated fibres in that shortening a muscle fibre
in rigor state resulted in an immediate drop in tension, after which half
of the drop in tension was recovered. The following slower phases of
tension recovery--a subsequent drop in tension and slow completion of
tension recovery--as seen in the activated state, do not occur in rigor
state. The magnitude of Young's moduli of fibres in rigor state generally
decreased from a value of 3.12 x 10(7) N m-2 at 40 kHz to 1.61 x 10(7) N
m-2 at about 100 Hz. Effects of increased viscosity of the incubation
medium, decreased interfilament distance in the relaxed state and variation
of rigor tension upon frequency dependence of complex Young's modulus have
been investigated. Variation of tension of crossbridges in rigor state
influenced to some extent the frequency dependence of the Young's modulus.
Recovery in relaxed state is not dependent on the viscosity of the medium.
Recovery in rigor is slowed down at raised viscosity of the incubation
medium, but less than half the amount expected if viscosity of the medium
would be the cause of internal friction of the half-sarcomere. Internal
friction of the half-sarcomere in the relaxed fibre at the same
interfilament distance as in rigor is different from internal friction in
rigor. It will be concluded that time necessary for recovery in rigor
cannot be explained by friction due to the incubation medium. Instead,
recovery in rigor expressed by the frequency dependence of the Young's
modulus has to be due to intrinsic properties of crossbridges. These
intrinsic properties can be explained by the occurrence of state
transitions of crossbridges in rigor.(ABSTRACT TRUNCATED AT 400 WORDS)
6. Yahia LH; Pigeon P; DesRosiers EA.
Viscoelastic properties of the human lumbodorsal fascia.
Journal of Biomedical Engineering, 1993 Sep, 15(5):425-9. (UI: 94048118)
Abstract: The purpose of this study is to provide better understanding of the
mechanical response of the lumbodorsal fascia to dynamic and static
traction loadings. Since the fascia shows a viscoelastic behaviour, tests
in which time is a variable were used, namely hysteresis and stress
relaxation. Load-strain and load-time curves obtained from the hysteresis
and stress-relaxation tests point out three different phenomena. First, an
increase in stiffness is noticed when ligaments are successively stretched,
i.e. strains produced by successive and identical loads decrease. Second,
if a sufficient resting period is allowed between loadings, stiffening is
reversed and strains tend to recover initial values. The third phenomenon,
observed in stress-relaxation tests as time progresses, is ligament
contraction in stretched and isometrically held samples. This third
phenomenon may be explained by the possibility that muscle fibres capable
of contracting spontaneously could be present in lumbodorsal fascia
ligaments.
7. De Winkel ME; Blange T; Treijtel BW.
The complex Young's modulus of skeletal muscle fibre segments in the high
frequency range determined from tension transients. Journal of Muscle
Research and Cell Motility, 1993 Jun, 14(3):302-10. (UI: 93367010)
Abstract: Stiffness measurements of muscle fibres are often based on
application of a length change at one end of the muscle fibre and recording
of the following tension change at the other end. In this study a method is
developed to determine in the high frequency range (up to 40 kHz) the
complex Young's modulus of skeletal muscle fibre as a function of frequency
from the tension transient, following a rapid stepwise length change
completed within 40 microseconds. For this purpose both a new mechanical
moving part of the displacement generating system and a force transducer
with a high natural frequency (70 kHz) had to be developed. In addition to
stiffness measurements of a silk fibre to test the displacement generating
system and the method of analysis, stiffness of skeletal muscle fibres in
relaxed and rigor state have been measured. The complex Young's moduli of
relaxed muscle fibres as well as muscle fibres in rigor state are frequency
dependent. In both cases the complex Young's modulus increases smoothly
with increasing frequency over a range of 250 Hz up to 40 kHz. The phase
angles of the responses remained almost constant at a value of 0.3 radians
for a fibre in rigor and 0.6 radians for a relaxed fibre. This leads to the
conclusion that for muscle fibres in rigor state the recovery in the
tension response to a step length change shows a continuous distribution of
relaxation times rather than a few discrete ones. Results of our stiffness
measurements are compared with results obtained from current viscoelastic
models used to describe stiffness of muscle fibre in this frequency
range.(ABSTRACT TRUNCATED AT 250 WORDS)
8. Wang K; McCarter R; Wright J; Beverly J; Ramirez-Mitchell R.
Viscoelasticity of the sarcomere matrix of skeletal muscles. The
titin-myosin composite filament is a dual-stage molecular spring.
Biophysical Journal, 1993 Apr, 64(4):1161-77. (UI: 93264564)
Abstract: The mechanical roles of sarcomere-associated cytoskeletal lattices
were investigated by studying the resting tension-sarcomere length curves
of mechanically skinned rabbit psoas muscle fibers over a wide range of
sarcomere strain. Correlative immunoelectron microscopy of the elastic
titin filaments of the endosarcomeric lattice revealed biphasic
extensibility behaviors and provided a structural interpretation of the
multiphasic tension-length curves. We propose that the reversible change of
contour length of the extensible segment of titin between the Z line and
the end of thick filaments underlies the exponential rise of resting
tension. At and beyond an elastic limit near 3.8 microns, a portion of the
anchored titin segment that adheres to thick filaments is released from the
distal ends of thick filament. This increase in extensible length of titin
results in a net length increase in the unstrained extensible segment,
thereby lowering the stiffness of the fiber, lengthening the slack
sarcomere length, and shifting the yield point in postyield sarcomeres.
Thus, the titin-myosin composite filament behaves as a dual-stage molecular
spring, consisting of an elastic connector segment for normal response and
a longer latent segment that is recruited at and beyond the elastic limit
of the sarcomere. Exosarcomeric intermediate filaments contribute to
resting tension only above 4.5 microns. We conclude that the interlinked
endo- and exosarcomeric lattices are both viscoelastic force-bearing
elements. These distinct cytoskeletal lattices appear to operate over two
ranges of sarcomere strains and collectively enable myofibrils to respond
viscoelastically over a broad range of sarcomere and fiber lengths.
9. McHugh MP; Magnusson SP; Gleim GW; Nicholas JA.
Viscoelastic stress relaxation in human skeletal muscle. Medicine and
Science in Sports and Exercise, 1992 Dec, 24(12):1375-82. (UI 93109059)
Abstract: Viscoelastic stress relaxation refers to the decrease in tensile
stress over time that occurs when a body under tensile stress is held at a
fixed length. The purpose of this study was to demonstrate viscoelastic
stress relaxation in human skeletal muscle. Resistance to stretch (tensile
force), hip flexion range of motion (ROM), and reflex contractile activity
(IEMG) of the hamstring muscle group were measured during a passive
straight leg raise. The testing protocol involved a first stretch to the
maximum tolerated ROM with the lower extremity held at that point for 45 s
(test 1). All 15 subjects tested (9 men, 6 women) had a stretch induced EMG
response. The onset of a sustained EMG response occurred at a specific hip
flexion angle in 10 subjects. These 10 subjects (6 men, 4 women) underwent
a second straight leg raise stretch (test 2) to a ROM 5 degrees below the
ROM at which the onset of EMG activity occurred in test 1. The stretch was
held at this hip flexion angle for 45 s. There was a significant decrease
in force at final ROM during the 45 s in test 1 (11.35 +/- 1.75 N, P <
0.0001) and in test 2 (4.2 +/- 1.55 N, P < 0.05). The percent decrease from
the force at the respective final ROM was not significantly different
between the tests (14.4 +/- 2.2% in test 1 and 13 +/- 2.3% in test 2). In
test 1 there was a significant decrease over time in IEMG of 59.71 +/-
16.01 microV.s (P < 0.01) which was not significantly correlated to the
decrease in force.(ABSTRACT TRUNCATED AT 250 WORDS)
10. Proske U; Morgan DL; Gregory JE.
Thixotropy in skeletal muscle and in muscle spindles: a review.
Progress in Neurobiology, 1993 Dec, 41(6):705-21.
Pub type: Journal Article; Review; Review, Academic. (UI 94188532)
---------------------------------------------------------------------------------
Hi; When you come to a comfortable conclusion in your search could you
possibly share the results? If not with the entire list at list via a note to
myself. I run a web site which I would like to have this on. Thank-you.
-mark sincock, lmt; http://www.lightlink.com/massage/msincock.html
----------------------------------------------------------------------
Regarding to your question about myofascial release formula's, I immediately
had to think about a slide Stanley Paris showed in one of his courses. It was
a slide of him performing a study on the strength of the lumbar fascia. He
was pulling on the skin and trying to rupture the fascia (he is fairly
radical in his tests) with manual force. He was unable to do this with the
use of his full body weight. It seems that the effect (which I really
consider very therapeutic, I use it a lot myself) is mainly based on the
GTO's. From his studies it doesn't seem to be realistic to think that we are
actually making a structural change in the connective tissue. Sorry I
couldn't give you a formula, unfortunately the bodies we have to work with
are not as ideal as we would like them to be, just to match our
theories......
Zoltan Bouwhuis, RPT e-mail:zdutchman@aol.com
---------------------------------------------------------------
Did you receive any replies to your question about thixotropy? I would be
interested to if you could forward a summary: or put a summary on the
BIomch listing
Trisha Bate School of Physiotherapy | pipes of pan...are our birthright"
Faculty of Health Sciences Latrobe University
EMAIL P.Bate@Latrobe.edu.au
------------------------------------------------------------------------------
here's the responses I got regarding time/force relation for thixotropy of
fascia.
My question was:
Could somebody help me in finding some research figures or formulas about the
time/force needed for mechanical outside pressure needed in dense human fascia
to result in a plasticity deformation?
I am not a biomech.scientist, but a practitioner of a method of deep
tissue manipulation called 'Rolfing'. Since a few years there is now a debate
going on in my school about whether thixotropy (tissue aggregate change from gel
to sol in response to mechanical pressure) is still a valid explanatory model
for the effect of myofascial release work. The amount of time and force for one
stroke in this work is rarely more than 1 min. with 20 kg max., yet often a
tissue release is already clearly felt or at least claimed. My personal
explanation of this work favors more a neuromuscular stimulation of the Golgi
Tendon Organs in the fascial envelopes. This seems to be supported by my
experience that this technique does not work anymore under local anesthesia,
plus by the verbal report by a colleague of mine who said that he once saw a
mathematical calculation which showed that one would need to apply several tons
(!) of pressure in order to achieve such a fast plasticity change in dense human
connective tissue.
I have been trying now to find such a formula myself in the literature
in order to check the validity of this claim, yet so far without success (Except
for getting overwhelmed by the hundreds of formulas in a book by Fung, Y.C
(Biomechanics, Mechanical Properties of Living Tissues, 1981). I believe that
clarity on this question could have an influence on probably 10 000 PT and other
practitioners who practice myofascial work worldwide. Could someone of you
professionals help us further?
Robert Schleip, Munich/Germany 100326.3427@compuserve.com
(Besides to BIOMCH-L, an almost identical text was posted to two other
listserves called PHYSIO and BODYWORK. All responses are listed below.
Feel free to add more if you have additional information or hints.)
---------------------------------------------------------------------------------
I don't believe human tissues deform plastically, without injury. Additionally
I do not believe there is a sol/gel transformation in most tissues, with
the only known possibility of such a transformation to occur in mucus 9but
that's not a tissue.
Check out the Handbook of Bioengineering and read about some of the
engineering terminology and concepts, I suggest.
Douglas Chang e-mail:dchang@sdcc3.ucsd.edu
---------------------------------------------------------------------------------
From: keg@strathspey.llnl.gov (Keith Grant)
I don't know if any of the articles/abstracts below could help you. They
are pretty much what I could come up with by doing a brief medline
search.
1. Levinson SF; Shinagawa M; Sato T.
Sonoelastic determination of human skeletal muscle elasticity.
Journal of Biomechanics, 1995 Oct, 28(10):1145-54. (UI: 96074869)
Abstract: It is not currently practical to directly measure viscoelastic
parameters in human muscles in situ. Methods used in vitro cannot readily
be applied, and motion analysis provides only a gross estimate. We report
on the application of a hybrid approach, sonoelastography, which uses
ultrasound to measure the propagation of shear waves induced by externally
applied vibrations. Because shear waves predominate in incompressible
viscoelastic media at low frequencies, sonoelastic data should be
comparable to those obtained using conventional means. We recorded
vibration propagation speeds as a function of applied load in the
quadriceps muscles of ten volunteers as they underwent a series of static
contractions. Data collection during dynamic contractions, not possible
with the current equipment, will be the subject of future experimentation.
Although statistically significant correlations were not uniformly obtained
above 60 Hz nor for propagation perpendicular to the muscle fibers, this is
felt to have resulted from deviations from the applied plane wave model.
Calculated values of Young's modulus for 30 Hz propagation parallel to the
muscle fibers were 7 +/- 3, 29 +/- 12 and 57 +/- 37 x 10(3) Nm-2 for
applied loads of 0, 7.5 and 15 kg, respectively. The corresponding values
at 60 Hz were 25 +/- 6, 75 +/- 61 and 127 +/- 65. These values were
statistically significant and linearly correlated with the applied load, as
expected. Our data represent the first in situ human measurements of their
kind. It is anticipated that sonoelastography will provide a useful adjunct
to the study of human biomechanics.
2. Roleveld K; Baratta RV; Solomonow M; Huijing PA.
Role of the tendon in the dynamic performance of three different
load-moving muscles. Annals of Biomedical Engineering, 1994 Nov-Dec,
22(6):682-91. (UI: 95177434)
Abstract: The effect of the tendon's viscoelastic properties on the dynamic
performance of three different load-moving muscles was determined. The
frequency response models of the cat's medial gastrocnemius (MG), extensor
digitorum longus (EDL), and tibialis anterior (TA) with and without their
tendons were derived under sinusoidal shortening-lengthening, manipulated
by orderly recruitment and derecruitment of motor units together with
firing rate increase and decrease. The passive load sizes applied to the
muscles were approximately 30%-40% of each muscle's maximal isometric
force. It was shown that the tendon has a moderate effect on the dynamic
response of muscles while moving loads of fixed mass. The MG and EDL
without their tendons show a decrease in high frequency gain (2-5 dB) and
increasing phase lag angles (7 degrees-9 degrees). In contrast, the TA
without its tendon shows an increase in high frequency gain (2 dB) and
decreasing phase lag angles (20 degrees) compared with the same muscle with
the tendon. It was concluded that tendon's viscoelastic properties have a
moderate effect during load-moving contractions, influencing the dynamic
performance of different muscles in a different manner.
3. Johnson GA; Tramaglini DM; Levine RE; Ohno K; Choi NY; Woo SL.
Tensile and viscoelastic properties of human patellar tendon.
Journal of Orthopaedic Research, 1994 Nov, 12(6):796-803. (UI:95074703)
Abstract: The tensile and viscoelastic properties of fresh-frozen,
nonirradiated human patellar tendon were investigated in two groups of 15
specimens: one group was from individuals 29-50 years old and the other
group was from individuals 64-93 years old. The central portion of each
patella-patellar tendon-tibia complex was subjected to cyclic
preconditioning, stress-relaxation, cyclic stress-relaxation, and load to
failure tests. For each age group, stress-relaxation and stress-strain
curves were obtained, from which percentage relaxation, ultimate tensile
strength, strain at failure, modulus, and strain energy density were
determined. Viscoelastic behavior was described with use of quasilinear
viscoelasticity. The younger group showed a 46 +/- 9% (mean +/- SD)
decrease in stress after 15 minutes, whereas the older group exhibited a 50
+/- 6% decrease. The values for ultimate tensile strength and strain at
failure, respectively, were 64.7 +/- 15.0 MPa and 14 +/- 6% for the younger
group and 53.6 +/- 10.0 MPa and 15 +/- 5% for the older group. Modulus
values were 660 +/- 266 MPa for the younger group and 504 +/- 222 MPa for
the older group. Except for ultimate tensile strength, which was 17% less
for the older group than for the younger one, no statistically significant
differences were found in tensile or viscoelastic properties. This study
indicated that there were minimal differences in biomechanical properties
of the substance of the patellar tendon between younger and older age
groups.
4. Best TM; McElhaney J; Garrett WE Jr; Myers BS.
Characterization of the passive responses of live skeletal muscle using
the quasi-linear theory of viscoelasticity.
Journal of Biomechanics, 1994 Apr, 27(4):413-9. (UI: 94245766)
Abstract: The tensile viscoelastic responses of live, innervated rabbit
skeletal muscle were measured and characterized using the quasi-linear
model of viscoelasticity. The tibialis anterior (TA) and extensor digitorum
longus (EDL) muscles of anesthetized New Zealand white rabbits were
surgically exposed and tested under in vivo conditions. Rate sensitivity of
the force-time history was observed in response to constant velocity
testing at rates from 0.01 to 2.0 Hz. Average hysteresis energy, expressed
as a percentage of maximum stored strain energy, was 39.3 +/- 5.4% and was
insensitive to deformation rate. The quasi-linear model, with constants
derived from relaxation testing, was able to describe and predict these
responses with correlation exceeding the 99% confidence interval for the
132 constant velocity tests performed (rmean = 0.9263 +/- 0.0373). The
predictive ability of this model was improved when compressive loading
effects on the muscle were neglected, rmean = 0.9306 +/- 0.0324. The rate
insensitivity of hysteresis energy was predicted by the model; however, the
absolute value of the hysteresis was underestimated (30.2 +/- 4.0%). Both
muscles demonstrated strikingly different elastic functions. Geometric
normalization of these responses (stress and strain) did not result in a
single elastic function capable of describing both muscles. Based on these
results, the quasi-linear model is recommended for the characterization of
the structural responses of muscle; however, further investigation is
required to determine the influence of muscle geometry and fiber
architecture on the elastic function.
5. De Winkel ME; Blange T; Treijtel BW.
High frequency characteristics of elasticity of skeletal muscle fibres
kept in relaxed and rigor state. Journal of Muscle Research and Cell
Motility, 1994 Apr, 15(2):130-44. (UI: 94327800)
Abstract: The viscoelastic properties of crossbridges in rigor state are
studied by means of application of small length changes, completed within
30 microseconds, to isometric skinned fibre segments of the iliofibularis
muscle of the frog in relaxed and rigor state and measurement of the
tension response. Results are expressed as a complex Young's modulus, the
real part of which denotes normalized stiffness, while the imaginary part
denotes normalized viscous mechanical impedance. Young's modulus was
examined over a wide frequency range varying from 5 Hz up to 50 kHz.
Young's modulus can be interpreted in terms of stiffness and viscous
friction of the half-sarcomere or in terms of elastic changes in tension
and recovery upon a step length change. The viscoelastic properties of
half-sarcomeres of muscle fibre segments in rigor state showed strong
resemblance to those of activated fibres in that shortening a muscle fibre
in rigor state resulted in an immediate drop in tension, after which half
of the drop in tension was recovered. The following slower phases of
tension recovery--a subsequent drop in tension and slow completion of
tension recovery--as seen in the activated state, do not occur in rigor
state. The magnitude of Young's moduli of fibres in rigor state generally
decreased from a value of 3.12 x 10(7) N m-2 at 40 kHz to 1.61 x 10(7) N
m-2 at about 100 Hz. Effects of increased viscosity of the incubation
medium, decreased interfilament distance in the relaxed state and variation
of rigor tension upon frequency dependence of complex Young's modulus have
been investigated. Variation of tension of crossbridges in rigor state
influenced to some extent the frequency dependence of the Young's modulus.
Recovery in relaxed state is not dependent on the viscosity of the medium.
Recovery in rigor is slowed down at raised viscosity of the incubation
medium, but less than half the amount expected if viscosity of the medium
would be the cause of internal friction of the half-sarcomere. Internal
friction of the half-sarcomere in the relaxed fibre at the same
interfilament distance as in rigor is different from internal friction in
rigor. It will be concluded that time necessary for recovery in rigor
cannot be explained by friction due to the incubation medium. Instead,
recovery in rigor expressed by the frequency dependence of the Young's
modulus has to be due to intrinsic properties of crossbridges. These
intrinsic properties can be explained by the occurrence of state
transitions of crossbridges in rigor.(ABSTRACT TRUNCATED AT 400 WORDS)
6. Yahia LH; Pigeon P; DesRosiers EA.
Viscoelastic properties of the human lumbodorsal fascia.
Journal of Biomedical Engineering, 1993 Sep, 15(5):425-9. (UI: 94048118)
Abstract: The purpose of this study is to provide better understanding of the
mechanical response of the lumbodorsal fascia to dynamic and static
traction loadings. Since the fascia shows a viscoelastic behaviour, tests
in which time is a variable were used, namely hysteresis and stress
relaxation. Load-strain and load-time curves obtained from the hysteresis
and stress-relaxation tests point out three different phenomena. First, an
increase in stiffness is noticed when ligaments are successively stretched,
i.e. strains produced by successive and identical loads decrease. Second,
if a sufficient resting period is allowed between loadings, stiffening is
reversed and strains tend to recover initial values. The third phenomenon,
observed in stress-relaxation tests as time progresses, is ligament
contraction in stretched and isometrically held samples. This third
phenomenon may be explained by the possibility that muscle fibres capable
of contracting spontaneously could be present in lumbodorsal fascia
ligaments.
7. De Winkel ME; Blange T; Treijtel BW.
The complex Young's modulus of skeletal muscle fibre segments in the high
frequency range determined from tension transients. Journal of Muscle
Research and Cell Motility, 1993 Jun, 14(3):302-10. (UI: 93367010)
Abstract: Stiffness measurements of muscle fibres are often based on
application of a length change at one end of the muscle fibre and recording
of the following tension change at the other end. In this study a method is
developed to determine in the high frequency range (up to 40 kHz) the
complex Young's modulus of skeletal muscle fibre as a function of frequency
from the tension transient, following a rapid stepwise length change
completed within 40 microseconds. For this purpose both a new mechanical
moving part of the displacement generating system and a force transducer
with a high natural frequency (70 kHz) had to be developed. In addition to
stiffness measurements of a silk fibre to test the displacement generating
system and the method of analysis, stiffness of skeletal muscle fibres in
relaxed and rigor state have been measured. The complex Young's moduli of
relaxed muscle fibres as well as muscle fibres in rigor state are frequency
dependent. In both cases the complex Young's modulus increases smoothly
with increasing frequency over a range of 250 Hz up to 40 kHz. The phase
angles of the responses remained almost constant at a value of 0.3 radians
for a fibre in rigor and 0.6 radians for a relaxed fibre. This leads to the
conclusion that for muscle fibres in rigor state the recovery in the
tension response to a step length change shows a continuous distribution of
relaxation times rather than a few discrete ones. Results of our stiffness
measurements are compared with results obtained from current viscoelastic
models used to describe stiffness of muscle fibre in this frequency
range.(ABSTRACT TRUNCATED AT 250 WORDS)
8. Wang K; McCarter R; Wright J; Beverly J; Ramirez-Mitchell R.
Viscoelasticity of the sarcomere matrix of skeletal muscles. The
titin-myosin composite filament is a dual-stage molecular spring.
Biophysical Journal, 1993 Apr, 64(4):1161-77. (UI: 93264564)
Abstract: The mechanical roles of sarcomere-associated cytoskeletal lattices
were investigated by studying the resting tension-sarcomere length curves
of mechanically skinned rabbit psoas muscle fibers over a wide range of
sarcomere strain. Correlative immunoelectron microscopy of the elastic
titin filaments of the endosarcomeric lattice revealed biphasic
extensibility behaviors and provided a structural interpretation of the
multiphasic tension-length curves. We propose that the reversible change of
contour length of the extensible segment of titin between the Z line and
the end of thick filaments underlies the exponential rise of resting
tension. At and beyond an elastic limit near 3.8 microns, a portion of the
anchored titin segment that adheres to thick filaments is released from the
distal ends of thick filament. This increase in extensible length of titin
results in a net length increase in the unstrained extensible segment,
thereby lowering the stiffness of the fiber, lengthening the slack
sarcomere length, and shifting the yield point in postyield sarcomeres.
Thus, the titin-myosin composite filament behaves as a dual-stage molecular
spring, consisting of an elastic connector segment for normal response and
a longer latent segment that is recruited at and beyond the elastic limit
of the sarcomere. Exosarcomeric intermediate filaments contribute to
resting tension only above 4.5 microns. We conclude that the interlinked
endo- and exosarcomeric lattices are both viscoelastic force-bearing
elements. These distinct cytoskeletal lattices appear to operate over two
ranges of sarcomere strains and collectively enable myofibrils to respond
viscoelastically over a broad range of sarcomere and fiber lengths.
9. McHugh MP; Magnusson SP; Gleim GW; Nicholas JA.
Viscoelastic stress relaxation in human skeletal muscle. Medicine and
Science in Sports and Exercise, 1992 Dec, 24(12):1375-82. (UI 93109059)
Abstract: Viscoelastic stress relaxation refers to the decrease in tensile
stress over time that occurs when a body under tensile stress is held at a
fixed length. The purpose of this study was to demonstrate viscoelastic
stress relaxation in human skeletal muscle. Resistance to stretch (tensile
force), hip flexion range of motion (ROM), and reflex contractile activity
(IEMG) of the hamstring muscle group were measured during a passive
straight leg raise. The testing protocol involved a first stretch to the
maximum tolerated ROM with the lower extremity held at that point for 45 s
(test 1). All 15 subjects tested (9 men, 6 women) had a stretch induced EMG
response. The onset of a sustained EMG response occurred at a specific hip
flexion angle in 10 subjects. These 10 subjects (6 men, 4 women) underwent
a second straight leg raise stretch (test 2) to a ROM 5 degrees below the
ROM at which the onset of EMG activity occurred in test 1. The stretch was
held at this hip flexion angle for 45 s. There was a significant decrease
in force at final ROM during the 45 s in test 1 (11.35 +/- 1.75 N, P <
0.0001) and in test 2 (4.2 +/- 1.55 N, P < 0.05). The percent decrease from
the force at the respective final ROM was not significantly different
between the tests (14.4 +/- 2.2% in test 1 and 13 +/- 2.3% in test 2). In
test 1 there was a significant decrease over time in IEMG of 59.71 +/-
16.01 microV.s (P < 0.01) which was not significantly correlated to the
decrease in force.(ABSTRACT TRUNCATED AT 250 WORDS)
10. Proske U; Morgan DL; Gregory JE.
Thixotropy in skeletal muscle and in muscle spindles: a review.
Progress in Neurobiology, 1993 Dec, 41(6):705-21.
Pub type: Journal Article; Review; Review, Academic. (UI 94188532)
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Hi; When you come to a comfortable conclusion in your search could you
possibly share the results? If not with the entire list at list via a note to
myself. I run a web site which I would like to have this on. Thank-you.
-mark sincock, lmt; http://www.lightlink.com/massage/msincock.html
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Regarding to your question about myofascial release formula's, I immediately
had to think about a slide Stanley Paris showed in one of his courses. It was
a slide of him performing a study on the strength of the lumbar fascia. He
was pulling on the skin and trying to rupture the fascia (he is fairly
radical in his tests) with manual force. He was unable to do this with the
use of his full body weight. It seems that the effect (which I really
consider very therapeutic, I use it a lot myself) is mainly based on the
GTO's. From his studies it doesn't seem to be realistic to think that we are
actually making a structural change in the connective tissue. Sorry I
couldn't give you a formula, unfortunately the bodies we have to work with
are not as ideal as we would like them to be, just to match our
theories......
Zoltan Bouwhuis, RPT e-mail:zdutchman@aol.com
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Did you receive any replies to your question about thixotropy? I would be
interested to if you could forward a summary: or put a summary on the
BIomch listing
Trisha Bate School of Physiotherapy | pipes of pan...are our birthright"
Faculty of Health Sciences Latrobe University
EMAIL P.Bate@Latrobe.edu.au
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