Muscle Pathophysiology and Treatment Flashcards
how does age influence muscle performance?
as you age, the CSA of type 2 fibers decreases
what are the 3 factors that influence muscle performance?
age, temperature, and immobilization/disuse
how does temperature affect muscle performance?
as temperature increases, so does elasticity
how does immobilization/disuse influence muscles performance?
if a muscle is immobilized in a shortened position, it will be injured with less force/stretch (the opposite is true of lengthened)
what is muscle tone?
the resistance to stretch in resting muscle
what contributes to normal resting tone?
titan and weak actin-myosin bonds
what is the role of weak actin-myosin bonds in muscle tone?
they provide resistance to stretch post prolonged contraction
what are some different muscles injuries?
excessive strain
contusions
excessive tension
lacerations
thermal stress
myotoxic agents
some local anesthetic agents
excessive use of corticosteroids
snake and bee venom
what 2 muscles injuries make up 90% of muscles injuries?
excessive strain and contusions
what is contusion?
heavy compressive forces or direct blow causes a hematoma to develop intramuscularly or intermuscularly
what is an intramuscular contusion hematoma?
the size of the muscle is limited by the fascia
what can intramuscular contusion hematoma lead to?
compartment syndrome
what is intramuscular contusion hematoma associated with?
muscles strain and bruising
which contusion hematoma is associated with more pain and loss of function?
intramuscular
what is intermuscular contusion hematoma?
ruptured muscles fascia causes blood to leak into interfacial and interstitial spaces causing less severe pain
what is a strain?
excessive pulling force on a muscle causing overstretching
what are the contributors to strain?
inadequate flexibility, strength, endurance, or rehab of previous injury
dyssynergistic muscle contraction
insufficient warm up
inadequate warm up
what are the 2 classifications of muscle injuries?
exercise-induced muscles injury (DOMS)
contusions
what causes exercise induced muscle injury?
increased activity
unaccustomed activity
excessive eccentric work
viral infection
secondary to muscles cell damage
what is a first degree (mild) strain?
minimal structural damage
minimal hemorrhage
early resolution
what is a 2nd degree (moderate) strain?
partial tear
large spectrum of injury
significant early functional loss
what is a 3rd degree (severe) strain?
complete tear
may require aspiration
what is aspiration?
using a needle to draw fluid out of a muscle
what does yellow/clear fluid indicate in aspiration?
joint fluid
what does red fluid indicate in aspiration?
blood
what does serosanguinous fluid in aspiration looks like and mean?
pinkish red fluid that indicates some level of bleeding
what muscles are most at risk for strain?
long fusiform muscles that cross 2 joints
muscles with propensity for eccentric contraction (hamstrings, quads, medial gastrocs, biceps brachii)
what is a common site for muscle strain?
at the musculotendinous junction
why is the musculotendinous junction a common site for muscle strain?
bc this is an area where compliant muscles fibers become noncompliant tendon
what are factors that could induce strain?
sudden overstretch
sudden contraction
decelerating limb
insufficient warm-up
lack of flexibility
steroid use
previous muscle injury
collagen disease
does muscle have regenerative capacity?
yes, muscles have a significant regenerative capacity bc muscle tissue can replace itself with muscle tissue
t/f: muscle has a similar healing process regardless of cause of injury
true!
the outcomes and time of healing of muscles depend on what 3 things?
type of injury, severity, and extent of injury
does pathology of muscle injury depend on the cause of injury?
yes
what is a potential consequence of muscle injury?
atrophy
what type of muscles have an increased potential for atrophy than antagonists?
antigravity muscles (ie. quads)
t/f: stronger, more flexible muscle heals faster and is less prone to injury
true!
what are the 3 phases of muscle healing?
- destruction phase
- repair phase
- remodeling phase
what is the destruction phase of muscle healing?
extensive proliferation of satellite cells that become myoblasts in the first few days post injury
cells maintain mitotic abilities and go through the cell cycle
what is the destruction phase of muscle healing characterized by?
necrosis, degeneration, and hematoma and edema
what is the repair phase of muscle healing?
hematoma formation fills the gaps b/w ruptured fibers
coagulation releases anaphylatoxins that activate sentinel cells triggering the inflammatory response and satellite cells to proliferate to reconstruct the injured site
what happens in the first day under the repair phase of muscle healing?
invasion of inflammatory cells including phagocytes
what happens in the 1st week of healing under the repair phase of muscle healing?
the injury is at it’s weakest point of the musculotendonous unit
what happens in the 1st few weeks of healing under the repair phase of muscle healing?
myofibers grow and mature
what happens in the final stage of the regenerative process?
integration of neural elements and formation of a functional neuromuscular junction
it is expected that there will be a return to function provided that there is…
continuity of the muscles fiber and innervation, vascular supply, and an intact ECM
what is the remodeling phase of muscle healing?
regenerated muscle matures and contracts with reorganization of the scar tissue
restoration of normal capacity and increased tensile strength over time
restoring the type 1 to type 3 collagen proportions
why do we need proper controlled mobility post acute phase?
it allows for scar formation, muscles regeneration, better fiber orientation, and normalization of tensile properties of muscles
t/f: prevention is easier than treatment of muscles injuries
true!
what are the treatments of muscle injuries?
prevention
patient education
controlled mobility
meds and modalities
ROM
what is the role of patient education in healing?
managing patient expectations
what is the typical progression of muscles injury PT?
PROM–>AAROM–> submaximal isometrics–> more maximal isometrics–> PREs isotonic
what are the effects of long term muscle immobility?
prolonged shortening: lose sarcomeres
prolonged lengthening: gain sarcomeres
what are the effects of short term immobility?
increased resistance to passive stretch through weak actin-myosin bonds
with a slow stretch, cross bridges have ____ time to detach
more
with a fast stretch, cross bridges have ____ time to detach
no
what is an example of a fast stretch consequence?
stretch reflex
what is muscle fatigue?
diminished response to repeated stimuli due to progressive deteriment of motor unit potentials leading to gradual decline in force production
what factors is muscle fatigue related to that may cause it?
decreased energy stores, oxygen, sensitivity, and availability of intracellular Ca2+
build up of H+
what are the signs of muscle fatigue?
discomfort (pain and cramping)
shaking/trembling contraction
contractions slow with reps
jerky, inconsistent movements
movement substitution
inability to continue low-intensity activity
inability to complete movement
decline in peak torque w/isokinetics
what are the signs of form fatigue?
jerky, inconsistent movements
movement substitution
inability to complete movement
what factors influence muscle fatigue?
health status
diet
lifestyle
environment factors
proteins in elderly are ___
reduced
vitamin D influences what 2 things?
type 2 muscles fibers and NTs
what is the role of B12 and folic acid in muscles?
correct homocysteine levels associated with CV disease, lower quad strength, and gait speed
how does reduced acid-producing diet affect muscle?
an acid-producing diet stimulates muscle catabolism
antioxidants can reduce what in elderly?
sarcopenia
