Week 9 Flashcards
(34 cards)
physical stress theory
- decreased stress = atrophy
- maintenance = homeostasis
- increased stress = hypertrophy
- overload = injury
- tissue death
acute injury
exercise induced muscle damage
- disruption and disarrangement of myofibrils and cytoskeletal structures
chronic injury
accumulation of exercise elicited increase in muscle protein synthesis inducing chronic muscle hypertrophy (need adequate recovery)
muscle hypertrophy ‘dose response relationship’
- fast to slow twitch fiber type transition
- muscle architecture change (increased pennation angle)
- vascularity (increased capillary number and flow)
IVD
largely avascular structure permitting movement, shock absorption and local distribution through spine
nucleus pulposis and annulus fibrosis
- NP - central gelatinous mass
- AF - outer fibrous ring
aging and degenerative disease impact on IVD
reduced height, proteoglycan and water content reduction
- less hydrated disk and loses structure
ligaments
dense bands of collagenous tissue spanning joint with bone to bone anchor points
ligament function
passive stability and proprioception
ligament contents
w c f v n
- 70% water
- 30% collagen (largely type 1 85% and type 3)
- fibroblasts (regulate extracellular matrix and ligament metabolism)
- vascular and neural supply
tendons
passive tissues important for transmitting force and allowing storage and release of strain energy during motion
tendon contents
c w t v s
- 15% collagen
- 80% water
- limited tenocytes
- limited vascular and nerve supply
healthy tendon
t c ecm
- uniform tenocyte numebrs with flattened shape
- wave collagen representation
- collagen organized and layered
- ECM structurally organized, consistent and balanced
most effective method for tendon adaptation
higher strain resistance training
- jump based training (increased tendon stiffness)
AT and RT effect on tendons
- aerobic training isolation has no effect on tendon properties
- AT and RT can clash with tendon improvement
- muscle tendon contraction does not influence tendon adaptation
tendon acute loading effect
increase in matrix metalloproteinases -> high release of breakdown products of collagen (net collagen loss in 24-36 hours after exercise) followed by collagen resynthesis (36-72 hours)
tendon overload
overload or lack of recovery = reduced load tolerance
articular cartilage
dense load bearing tissue absorbing and dissipating weight, lubricating and permitting smooth and frictionless movement
articular cartilage contents
largely avascular and anural (lacking healing potential and suscptible to degenerative disease)
- receives nutrients from subchondral bone or synovial fluid
articular cartilage layers
- zone 1 (superficial)
- zone 2 (transitional)
- zone 3 (deep)
- zone 4 (calcified attached to bone)
chondrocytes
- building blocks of cartilage
- ECM, collagen and proteoglycans (interact to produce strength, stiffness and resistance to tensile/compressive stresses)
- hyaluronic acid and water (60-80%)
osteoarthritis
softer and reduced tensile strength
- cannot dfeal with compressive forces
- loses compressive stiffness
- cartilage thinning
corticol/trabecular bone response to load and exercise
age = increased porosity, hypermineralization, accumulation of microdamage, strength under tension and compression decline 2% per decade from 30s
trabecular/cancellous/spongey bone
porosity 40-95%
- age = trabecular bone thinner and less closely spaced
- strength reduction by 10% per decade
