Start out with a search of medical journals at PubMed at the National
Library of Medicine of the National Institutes of Health:
http://ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed
Search term: microfibrosis
This will bring up summaries of articles. Select "Abstract" from the
drop-down menu on the bar above the results and click Display (left on
the bar). That will bring up the abstracts for the articles, for
example:
1: Pacing Clin Electrophysiol 1997 Feb;20(2 Pt 2):397-413
Microfibrosis produces electrical load variations due to loss of
side-to-side
cell connections: a major mechanism of structural heart disease
arrhythmias.
Spach MS, Boineau JP.
Department of Pediatrics, Duke University Medical Center, Durham,
North Carolina
27710, USA.
The purpose of this article is to demonstrate how adaptive changes in
myocardial
microstructure provide mechanisms for emergent new conduction
disturbances that
initiate reentrant arrhythmias. The mechanisms are based on
discontinuous
conduction phenomena produced by increases in cellular loading; these
increases
result from changes in the normal distribution of the gap junctions.
Recent
studies that at a microscopic level propagation in normal mature
cardiac muscle
is stochastic. For example, the nonuniform and irregular distribution
of the gap
junctions in such normal muscle produces load variations that are
associated
with changes in Vmax inside individual cells during both longitudinal
and
transverse propagation. The stochastic nature of normal propagation at
a
microscopic level offers considerable protection against arrhythmias
by
reestablishing the general trend of wavefront movement after small
variations in
excitation events occur. If such microscopic diversity is decreased,
large
fluctuations in load develop that are distributed over more cells than
usual.
The decrease in diversity may be caused by loss of side-to-side
coupling between
fibers, which produces relatively isolated groups of cells with
microfibrosis.
With loss of side-to-side fiber coupling, the myocardial architecture
may fail
to reestablish a smoothed wavefront at the macroscopic level. Spatial
nonuniformities of electrical loading then give rise to conduction
block and
reentry.
Publication Types:
Review
Review, Tutorial
PMID: 9058844 [PubMed - indexed for MEDLINE]
2: J Cardiovasc Electrophysiol 1996 Dec;7(12):1145-53
Nonuniform anisotropy is responsible for age-related slowing of
atrioventricular
nodal reentrant tachycardia.
Anselme F, Frederiks J, Papageorgiou P, Monahan KM, Epstein LM, Spach
MS,
Josephson ME.
Harvard-Thorndike Institute of Electrophysiology, Beth Israel
Hospital, Boston,
MA 02215, USA.
INTRODUCTION: AV nodal reentrant tachycardia cycle length has been
shown to be
longer in the elderly population. Microfibrosis associated with aging
producing
nonuniform anisotropic conduction or changes in membrane ionic
properties could
explain this finding. Etc.
PMID: 8985803 [PubMed - indexed for MEDLINE]
3: J Cardiovasc Electrophysiol 1994 Feb;5(2):182-209
Initiating reentry: the role of nonuniform anisotropy in small
circuits.
Spach MS, Josephson ME.
Department of Pediatrics, Duke University Medical Center, Durham,
North Carolina
27710.
Until recently only two types of media have been considered to provide
the
nonuniformities necessary to initiate cardiac reentry: (1) continuous
isotropic
media with intrinsic repolarization inhomogeneities; and (2)
continuous
isotropic media free of inhomogeneities in which repolarization
nonuniformities
are introduced transiently. The purpose of this article is to
establish cellular
coupling as a basis for arrhythmias by placing a new type of
inhomogeneity,
nonuniform anisotropy due to sparse side-to-side coupling between
cells, in an
overall perspective with the other nonuniformities that lead to
reentry. Etc.
Publication Types:
Review
Review, Tutorial
PMID: 8186887 [PubMed - indexed for MEDLINE]
4: Exerc Sport Sci Rev 1989;17:157-85
Eccentric action of muscles: physiology, injury, and adaptation.
Stauber WT.
Eccentric muscle action deserves special consideration from the
standpoint of
physiology, adaptation, and training... Does microfibrosis represent a
problem of overtraining and eventually limit performance, or is it
advantageous
for success? Etc.
Publication Types:
Review
Review Literature
PMID: 2676546 [PubMed - indexed for MEDLINE]
At the top far right of each abstract there are two hyperlinks
"Related articles" and "Links". Clicking on "Related articles" will
bring up summaries of articles having the same general subject matter.
There are literally hundreds of related articles. (108 for the Stauber
article alone, for instance.) Selecting "Abstract" will show the
detailed abstract for each article or for the articles that have been
checked in the small box next to each article. Summaries or abstracts
can be saved to a file using the "Send" button.
Some of the abstracts will have additional hyperlinks to the full text
of the articles. Clicking on these links will lead to the web sites of
the journals in which the articles appeared. Some of these journals
allow free access to the html-formatted text or .pdf of the articles,
while others may require a fee.
For example:
3: Circ Res 2000 Feb 18;86(3):302-11
Electrophysiological effects of remodeling cardiac gap junctions and
cell size:
experimental and model studies of normal cardiac growth.
Spach MS, Heidlage JF, Dolber PC, Barr RC.
Department of Pediatrics, Duke University Medical Center, Durham, NC
27710, USA.
cspach@acpub.duke.edu
The increased incidence of arrhythmias in structural heart disease is
accompanied by remodeling of the cellular distribution of gap
junctions to a
diffuse pattern like that of neonatal cardiomyocytes. Accordingly, it
has become
important to know how remodeling of gap junctions due to normal growth
hypertrophy alters anisotropic propagation at a cellular level
(V(max)) in
relation to conduction velocities measured at a macroscopic level.
Etc.
PMID: 10679482 [PubMed - indexed for MEDLINE]
Clicking on the hyperlink graphic for the full text of this article
causes a new window to be opened with the url:
http://www.ncbi.nlm.nih.gov:80/entrez/utils/fref.fcgi?http://circres.ahajournals.org/cgi/pmidlookup?view=full&pmid=10679482
This resolves to:
http://circres.ahajournals.org/cgi/content/full/86/3/302
which leads to the web page for the American Heart Association's
journal Circulation Research, where the article can be viewed or
downloaded.
Some other articles that have free full-text links are:
1: Med Sci Sports Exerc 2001 May;33(5):783-90
Human hamstring muscles adapt to eccentric exercise by changing
optimum length.
Brockett CL, Morgan DL, Proske U.
Department of Physiology, Monash University, Clayton, Victoria, 3168,
Australia.
Camilla.Brockett@med.monash.edu.au
PURPOSE: It is now established that unaccustomed eccentric exercise
leads to
muscle fiber damage and to delayed-onset muscle soreness (DOMS) in the
days
after exercise. However, a second bout of eccentric exercise, a week
after the
first, produces much less damage and soreness. The purpose of this
study was to
provide evidence from muscle mechanical properties of a proposed
mechanism for
this training effect in human hamstring muscles. Etc.
PMID: 11323549 [PubMed - indexed for MEDLINE]
http://www.ncbi.nlm.nih.gov:80/entrez/utils/fref.fcgi?http://www.acsm-msse.com/article.asp?ISSN=0195-9131&VOL=33&ISS=5&PAGE=783
Resolves to:
http://www.acsm-msse.com/article.asp?ISSN=0195-9131&VOL=33&ISS=5&PAGE=783
which leads to abstract on the journal site with options to view full
text html or download in .pdf.
2: Eur J Appl Physiol 2001 Sep;85(5):466-71
Adaptation to chronic eccentric exercise in humans: the influence of
contraction
velocity.
Paddon-Jones D, Leveritt M, Lonergan A, Abernethy P.
Department of Surgery, University of Texas Medical Branch, Galveston
77550, USA.
djpaddon@utmb.edu
We compared changes in muscle fibre composition and muscle strength
indices
following a 10 week isokinetic resistance training programme
consisting of fast
(3.14 rad x s(-1)) or slow (0.52 rad x s(-1)) velocity eccentric
muscle
contractions. Etc.
PMID: 11606016 [PubMed - indexed for MEDLINE]
http://www.ncbi.nlm.nih.gov:80/entrez/utils/fref.fcgi?http://link.springer-ny.com/link/service/journals/00421/bibs/1085005/10850466.htm
Resolves to:
http://link.springer-ny.com/link/service/journals/00421/contents/01/00467/index.html
which leads to journal abstract with options to read full-text html or
download .pdf.
3: J Appl Physiol 1996 Oct;81(4):1677-82
Greater initial adaptations to submaximal muscle lengthening than
maximal
shortening.
Hortobagyi T, Barrier J, Beard D, Braspennincx J, Koens P, Devita P,
Dempsey L,
Lambert J.
Biomechanics Laboratory, East Carolina University, Greenville, North
Carolina
27858, USA. hphortob@ecuvm.cis.ecu.edu
The purpose of this study was to compare the short-term strength and
neural
adaptations to eccentric and concentric training at equal force
levels.
Forty-two sedentary women (age = 21.5 yr) were ranked based on the
initial
quadriceps strength score, and trios of subjects were randomly
assigned to
either an eccentric (n = 14), a concentric (n = 14), or a
nonexercising control
group (n = 14). Etc.
Publication Types:
Clinical Trial
Randomized Controlled Trial
PMID: 8904586 [PubMed - indexed for MEDLINE]
http://jap.physiology.org/cgi/content/full/81/4/1677
Articles not available online.
(Most libraries can obtain the journal articles on request. The PubMed
web site will give a list of libraries that carry the journals if the
"Links" hyperlink is clicked and "outlink" is chosen from the popup
menu.)
Selected articles on Cardiac Arrhythmia.
1: Circ Res 1995 Mar;76(3):366-80
The stochastic nature of cardiac propagation at a microscopic level.
Electrical
description of myocardial architecture and its application to
conduction.
Spach MS, Heidlage JF.
Department of Pediatrics, Duke University Medical Center, Durham, NC
27710.
The object of this study is to present evidence that the myocardial
architecture
creates inhomogeneities of electrical load at the cellular level that
cause
cardiac propagation to be stochastic in nature; ie, the excitatory
events during
propagation are constantly changing and disorderly in the sense of
varying
intracellular events and delays between cells. Etc.
PMID: 7859383 [PubMed - indexed for MEDLINE]
2: Cardiovasc Pathol 2001 Jul-Aug;10(4):169-77
The role of myocardial gap junctions in electrical conduction and
arrhythmogenesis.
Kanno S, Saffitz JE.
Department of Surgery and the Center for Cardiovascular Research,
Washington
University School of Medicine, St. Louis, MO 63110, USA.
Electrical activation of the heart requires cell-cell transfer of
current via
gap junctions, arrays of densely packed protein channels that permit
intercellular passage of ions and small molecules. Because current
transfer
occurs only at gap junctions, the spatial distribution and biophysical
properties of gap junction channels are important determinants of the
conduction
properties of cardiac muscle. Gap junction channels are composed of
members of a
multigene family of proteins called connexins. Etc.
Publication Types:
Review
Review, Tutorial
PMID: 11600334 [PubMed - indexed for MEDLINE]
4: Circ Res 1987 Dec;61(6):815-23
A model study of the effects of the discrete cellular structure on
electrical
propagation in cardiac tissue.
Rudy Y, Quan WL.
Department of Biomedical Engineering, Case Western Reserve University,
Cleveland, Ohio 44106.
The effects of the discrete cellular structure on propagation of
electrical
excitation in cardiac muscle were studied in a one-dimensional fiber
model
containing a periodic intercalated disk structure. Globally, the
macroscopic
velocity of propagation follows the behavior associated with
propagation in a
continuous tissue (except for high values of disk resistance). Etc.
PMID: 3677338 [PubMed - indexed for MEDLINE]
Selected articles on Eccentric Muscle Action.
2: J Physiol 1993 Aug;468:487-99
Excitation failure in eccentric contraction-induced injury of mouse
soleus
muscle.
Warren GL, Lowe DA, Hayes DA, Karwoski CJ, Prior BM, Armstrong RB.
Muscle Biology and Vision Research Laboratories, University of
Georgia, Athens
30602.
1. Histological evidence suggests that the force deficit associated
with
eccentric contraction-induced muscle injury is due to structural
damage to
contractile elements within the muscle fibre. Alternatively, the force
deficit
could be explained by an inability to activate the contractile
proteins. It was
the objective of this study to investigate the latter possibility.
Etc.
PMID: 8254518 [PubMed - indexed for MEDLINE]
3: Int J Sports Med 1983 Aug;4(3):177-83
Adaptive response in human skeletal muscle subjected to prolonged
eccentric
training.
Friden J, Seger J, Sjostrom M, Ekblom B.
The peripheral adaptation process associated with repeating eccentric
training
over a longer period of time was studied in m. vastus lateralis of
eleven
healthy males aged 24 +/- 4 years. The maximal dynamic concentric
muscle
strength was only slightly improved after 8 weeks of training.
However,
eccentric work capacity was dramatically increased (375%). Etc.
PMID: 6629600 [PubMed - indexed for MEDLINE]
4: J Biomech 1997 May;30(5):447-55
Neural adaptations with chronic physical activity.
Enoka RM.
Department of Kinesiology, University of Colorado, Boulder 80309-0354,
USA.
Chronic activity patterns, such as strength training, limb
immobilization, and
aging, produce marked adaptations in both the muscular and nervous
systems. In
this brief review, some of the involved mechanisms are examined as
they are
revealed through studies on the maximality, specificity, and pattern
of the
neural drive to muscle. The studies on maximality indicate that it is
difficult
to activate maximally a muscle by voluntary command, the capacity
varies across
muscles, tasks, and training, and the maximum discharge rates of motor
neurons
decreases with immobilization and increases with strength training.
Etc.
Publication Types:
Lectures
Review
Review, Tutorial
PMID: 9109556 [PubMed - indexed for MEDLINE]
5: J Orthop Sports Phys Ther 1994 Jan;19(1):12-7
The warm-up procedure: to stretch or not to stretch. A brief review.
Smith CA.
UCT Sports Injuries Clinic, University of Cape Town, South Africa.
Stretching exercises are either performed alone or with other
exercises as part
of the athlete's warm-up. The warm-up is designed to increased
muscle/tendon
suppleness, stimulate blood flow to the periphery, increase body
temperature,
and enhance free, coordinated movement. The purpose of this paper is
to review
the literature regarding stretching, with the aim of defining its role
during
the warm-up. Implications of stretching on muscle/tendon flexibility,
minimizing
injury, enhancing athletic performance, and generally preparing the
athlete for
exercise are discussed. Physiology applied to stretching is also
discussed
together with different related techniques and practical aspects. A
proposed
model stretching regime is presented based on the literature reviewed.
Publication Types:
Review
Review, Tutorial
PMID: 8156057 [PubMed - indexed for MEDLINE]
6: J Biomech 1997 Jan;30(1):27-33
Dynamic force responses of muscle involving eccentric contraction.
Krylow AM, Sandercock TG.
Department of Biomedical Engineering, Northwestern University,
Evanston, IL
60208, USA.
Normal movements commonly involve dynamic conditions where active
muscles
operate against other muscle forces, or against forces arising from
decelerating
limb inertia. In these situations, some active muscles spanning the
joint are
lengthened. Presently, our understanding of the muscle mechanics which
operate
in lengthening contractions, or during large muscle length changes is
incomplete. Etc.
PMID: 8970921 [PubMed - indexed for MEDLINE]
7: J Appl Physiol 1996 Jun;80(6):1958-62
Effect of phase of stimulation on acute damage caused by eccentric
contractions
in mouse soleus muscle.
Stevens ED.
Department of Zoology, University of Guelph, Ontario, Canada.
dstevens@uoguelph.ca
Eccentric contractions (activation during muscle lengthening) can
cause muscle
damage. The effect of phase of stimulation on the extent of muscle
damage was
studied by using the work-loop method. For the work-loop method, the
muscle was
subjected to sinusoidal length changes at 2 Hz. Etc.
PMID: 8806900 [PubMed - indexed for MEDLINE]
9: Med Sci Sports Exerc 1984;16(1):26-8
Biomechanics and neuromuscular performance.
Komi PV.
Research of neuromuscular performance offers a unique possibility for
integration of biomechanics, muscle physiology, and neurophysiology.
This
integration is especially desirable in situations where recording of
neuromuscular function is made under normal movement conditions of the
entire
physiological range. This would improve the possibilities to
investigate more
exactly the interrelationship between structural aspects of the
neuromuscular
system and performance characteristics. Stretch-shortening cycle, a
normal way
of muscle function needs also to be investigated more both from the
neurophysiological and mechanical viewpoints. Etc.
PMID: 6708777 [PubMed - indexed for MEDLINE]
10: Int J Sports Med 1986 Jun;7(3):137-43
Effects of prestretch intensity on mechanical efficiency of positive
work and on
elastic behavior of skeletal muscle in stretch-shortening cycle
exercise.
Aura O, Komi PV.
Mechanical efficiency of positive work (eta+) and elastic behavior of
human
skeletal muscles were investigated on a special sledge apparatus which
allowed
the use of the normal stretch-shortening cycle exercises. Twenty-five
young men
were investigated in a total of 92 exercise situations, in which the
intensity
of the prestretch (eccentric contraction) was different, but the
shortening
phase (concentric contraction) was kept constant in all conditions.
Etc.
PMID: 3733310 [PubMed - indexed for MEDLINE]
11: Acta Physiol Scand 1994 Nov;152(3):287-93
Potentiation of concentric plantar flexion torque following eccentric
and
isometric muscle actions.
Svantesson U, Grimby G, Thomee R.
Department of Rehabilitation Medicine, University of Goteborg,
Sahlgrenska
Hospital, Sweden.
In a stretch-shortening cycle (SSC) the concentric muscle action is
enhanced by
a preceding eccentric muscle action. The hypothesis of the present
study is that
a preceding isometric action can also have an effect on a following
concentric
action, but to a lesser degree. Etc.
PMID: 7872006 [PubMed - indexed for MEDLINE]
13: J Muscle Res Cell Motil 2001;22(4):301-10
Passive stretching does not protect against acute contraction-induced
injury in
mouse EDL muscle.
Black JD, Stevens ED.
Department of Zoology, University of Guelph, Ontario, Canada.
A popular part of many athletes pre-game regime is to stretch. We
examined
whether a pre-injury stretching protocol could prevent acute
contraction-induced
injury. The in situ extensor digitorum longus (EDL) muscle of an
anesthetized
mouse (80 mg/kg intra-peritoneal) was used. Damage to the muscle from
eccentric
contraction-induced injury was quantified by the deficit in tetanic
force
production, and was not confounded by metabolic fatigue. Etc.
PMID: 11808770 [PubMed - indexed for MEDLINE]
14: Med Sci Sports Exerc 1990 Aug;22(4):436-43
Muscle strain injuries: clinical and basic aspects.
Garrett WE Jr.
Division of Orthopaedic Surgery, Duke University Medical Center,
Durham, NC
27710.
Indirect or strain injury to muscle is a common cause of athletic
disability.
Strain injuries often occur during powerful muscle eccentric
contractions.
Clinical studies suggest that most injuries cause partial disruption
of certain
characteristic muscles. Diagnostic imaging studies can demonstrate the
location
of many injuries. Laboratory studies show that partial and complete
injuries
exhibit disruption of muscle fibers near the muscle-tendon junction.
Healing of
partial injuries is characterized by an initial inflammatory response
followed
by a healing phase marked by fibrosis. Etc.
Publication Types:
Review
Review, Tutorial
PMID: 2205779 [PubMed - indexed for MEDLINE]
15: J Appl Physiol 1993 Oct;75(4):1545-51
Effect of training on eccentric exercise-induced muscle damage.
Balnave CD, Thompson MW.
Department of Biological Sciences, Faculty of Health Sciences,
University of
Sydney, Lidcombe, New South Wales, Australia.
Eccentric muscle contractions generate delayed onset muscle soreness
(DOMS),
possibly as a result of the high tensions involved causing muscle
damage. Muscle
function, serum indicators of muscle damage, and DOMS were
investigated
throughout a training regimen that involved a 40-min eccentric walk
down a 25%
gradient on a treadmill at 6.4 km/h once a week for 8 wk. Serum
creatine kinase
and myoglobin concentrations were used as indicators of muscle damage,
and both
demonstrated a delayed increase after the exercise protocol. The
muscles that
contracted eccentrically exhibited low-frequency fatigue, as well as
decreases
in muscle fatigability and maximal voluntary contraction force, which
were
greatest immediately postexercise. Although the results show that
training
reduces DOMS, the serum muscle protein response, and muscle function
impairment,
the time courses of these adaptations are different. It is suggested
that the
function of the muscle can be impaired without apparent muscle damage.
PMID: 8282602 [PubMed - indexed for MEDLINE]
16: Scand J Rehabil Med 1981;13(1):11-6
Adaptation to peripheral muscle training.
Gaffney FA, Grimby G, Danneskiold-Samsoe B, Halskov O.
Ten healthy subjects underwent a 6-week dynamic exercise program
designed to put
a high relative load on individual muscle groups while maintaining low
central
circulatory stress levels. This was done to test the hypothesis that
such
"peripheral" training could produce skeletal muscle adaptation at low
levels of
myocardial work. Such a program may be useful in rehabilitating
patients whose
myocardial disease prevents adequate levels of participation in the
traditional
types of large muscle training. Etc.
PMID: 7268326 [PubMed - indexed for MEDLINE]
18: J Physiol 1987 Oct;391:1-11
Human muscle strength training: the effects of three different
regimens and the
nature of the resultant changes.
Jones DA, Rutherford OM.
Department of Medicine, University College London, Rayne Institute.
1. Increases in strength and size of the quadriceps muscle have been
compared
during 12 weeks of either isometric or dynamic strength training. 2.
Isometric
training of one leg resulted in a significant increase in force (35
+/- 19%,
mean +/- S.D., n = 6) with no change in the contralateral untrained
control leg.
3. Quadriceps cross-sectional area was measured from mid-thigh X-ray
computerized tomography (c.t.) scans before and after training. The
increase in
area (5 +/- 4.6%, mean +/- S.D., n = 6) was smaller than, and not
correlated
with, the increase in strength. 4. The possibility that the stimulus
for gain in
strength is the high force developed in the muscle was examined by
comparing two
training regimes, one where the muscle shortened (concentric) and the
other
where the muscle was stretched (eccentric) during the training
exercise. Etc.
PMID: 3443943 [PubMed - indexed for MEDLINE]
19: Eur J Appl Physiol Occup Physiol 1995;72(1-2):183-5
Changes induced by eccentric training on force-velocity relationships
of the
elbow flexor muscles.
Martin A, Martin L, Morlon B.
Groupe Analyse du Mouvement, Universite de Bourgogne, BP 138, F-21004,
Dijon,
France.
The aim of this study was to examine the effects of a short term
eccentric
training period on force-velocity relationships of the elbow flexor
muscles.
Etc.
PMID: 8789592 [PubMed - indexed for MEDLINE]
20: Mech Ageing Dev 1995 Sep 15;83(3):185-200
Prolonged recovery and reduced adaptation in aged rat muscle following
eccentric
exercise.
McBride TA, Gorin FA, Carlsen RC.
Department of Neurology School of Medicine, University of California,
Davis
95616, USA.
We tested the hypothesis that exposure to eccentric (lengthening)
contractions
results in greater damage and more prolonged recovery in aged rat
muscle (32
months) than in adult muscle (6 months), and that the adaptation
usually
associated with a single exposure to eccentric exercise is reduced in
the aged
muscle.Etc.
PMID: 8583836 [PubMed - indexed for MEDLINE]
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