Term
| 4 characteristics of skeletal muscle: EEIA |
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Definition
extensibility- ability to be stretched or increase in length
elasticity- ability to return to normal length after extension or contraction
irritability- ab to respond to nerve stimulus or external (mechanical) blow
ability to develop tension- (used to be contraction) but can be isotonic |
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Definition
| single motor neuron and all muscle fibres it innervates |
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Term
| parallel elastic component |
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Definition
| passive elastic property of musc, from CT of muscle, endomysium, perimysium, and epimysium |
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| passive elastic property of musc from tendons- acts like a spring, stores elastic energy when tensed muscled stretched |
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Definition
| passive elastic prop of musc from Actin and Myosin filaments and cross-bridges.- enabling tension dvlmpt |
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Definition
| ability to stretch or shorten over time |
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Definition
| membrane surrounding a muscle fibre |
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Definition
| specialized cytoplasm containing myofibrils (2 types: actin, myosin), nuclei, and mitochondria |
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Definition
a band- dark, has thick myosin and 6 thin smooth actin,
i band- only actin
both i and a bands attached to z lines
h zone in centre of a band- only myosin |
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Term
| contraction of a sarcomere |
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Definition
-actin filaments slide toward eachoth
zlines move towards a bands
a bands stay same size
h zone disappears
i band narrows
cross bridges form links with actin
# of linkages~ force production and nrg expenditure |
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Definition
network of membranous channels EXTERNAL to each fibre, transverse tubules transect fibres INTERNALLY- pass thru completely
=channels for transport for electrochemicals |
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Definition
| CT round entire muscle connects to tendon |
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Definition
| CT around bundles of musc fibres |
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Definition
| CT covering single muscle cell |
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Definition
| thin membrane around muscle cell |
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Term
| summation (aka wave summation or freq summation) |
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Definition
| occurs in musc fibre when nerve impulses occur rapidle, when muslce already in tension (tension increases in additive (stepwise manner) |
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Definition
| fibre repeat activated by stimuli in rapid succession- max tension lvl maintain until stimulation stops |
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Definition
(all fibres are same type in one mu_)
during voluntary and concentric contraction- pattern of recruitment controlled by size of motor unit= SIZE PRINCIPLE
small MU with slow-twitch fibres=lowest fire threshold- recruited first
largest MU-fast twitch B fibres- highest threshold- recruited last |
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Term
| muscle fibre type- Fast twitch fibre (type II) |
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Definition
fibres reach peak tension relativly quickly- for fast powerful, larger diameter, high force, eaisly fatigued
type IIa- fast twitch oxidative(FOG) and type IIb- fast twitch glycolytic (FG)
can increase by resistance training, and convert FT from type IIb to IIa
fibre type affected by age and obesity |
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Term
| slow twitch fibres (type I-SO) |
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Definition
fibres reach peak tension relatively slowly- 7x longer to reach peak tension, smaller diameter, aerobic, slow to fatigue, endurance
has less ATPase than fast-twitch, has higher mitochondrial concentra then fast-twitch, and has low gycolytic enzyme concentration |
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Term
| parallel fiber arrangement |
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Definition
pattern of fibres w/in a musc in which fibres roughly parallel to longitudingal axis of muscle
-for muscle shortening
-for fast speed movement- sarcomere are in series and greater shortening- ie sartorius |
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Term
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Definition
pattern of fibres within musc with short fibres attaching to one or more tendons (uni, bi or mulipennate)
-promotes musc force production
-b/c more muslce fibres pulling on the tendon ie deltoid |
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Term
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Definition
when fibres of pennate shorten- rotate about tendon attachment (s)- and increase angle of pennation
- greater angle=smaller effective force transmitted to bone and musc
-when greater than 60 degrees, the effetive force transferred to tendon is less than half produced by fibres
-but good cuase can pack more muslce= greater force |
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Definition
| contraction shortening of muscle with change in angle of joint |
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Definition
| muscular tension dvlps but no change in muslce length occurs |
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Definition
contraction where musc lengthens as it's stimulated to dvlp tension
(ie. lowering weight, or slowly against gravity, slowing down limbs or landing in running)
max eccentric contra anre up to 50% stronger than concentric |
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Term
| why more muscle strain injuries eccentric contractions |
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Definition
submax (and maximal) eccentric- uses fewer MU than concentric- more force on each MU and fibre
pro-increase musc size and strength- bu t assoc with soreness and structural damage |
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Definition
| constant velocity of musc contraction thru entire range of motion |
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Definition
| constant force output throught ROM |
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Definition
| role played by muscle acting to produce a movement- primary mover |
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Definition
role played by muscle to slow or stop a movement- resist action of prime mover- opposite joint movement to agonist
-braking/controling
dvlp eccentric tension same time as agonist |
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Definition
| musc that stabilize or hold body part to resist pull of other muscles (ie traps and rhomoids on scapula) |
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Definition
| musc that eliminate or neutralize the unwanted action prod by agonist (ie pronator teres has to stop biceps supination) |
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Definition
| limited ability of a two-joint muscle to produce force when joint position places the muscle on slack |
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Definition
| inability of a two-joint muslce to stretch to the extent required to allow a full ROM at all joints crossed (ie can't plant feet when in downward dog, bc tight calves) |
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Term
| force-velocity relationship |
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Definition
max force that musc can dvlp dep on the velocity of muscle shortening or lengthening- light weight, faster it can contract. as load increases- it reaches max isometric contraction (velocity=0)- then heavier load, musc lengthens eccentrically
-eccentric force output increases with increasing velocity up till max load that can be controlled
-also stronger the muscle, the greater magnitude of isometric maximum |
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Term
| length-tension relationship |
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Definition
the amount of force produced is related to the length at wh musc held- single fibre peak tension at resting length or up to 130% of resting length=optimal amt crossbridges
-passive elastic tissue PEC can store strain energy and increase force output of stretched muscle
stretched elastic components SEC can add to force output of muscle when it is lengthened |
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Term
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Definition
| extensibility- ability to be stretched or increase in length |
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Definition
| elasticity- ability to return to normal length after extension or contraction |
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Definition
| irritability- ab to respond to nerve stimulus or external (mechanical) blow |
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Term
| ability to develop tension (characteristic of skeletal muscle) |
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Definition
| ability to develop tension- (used to be contraction) but can be isotonic |
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Term
stretch-shortening cycle
What is it
two reasons why it works |
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Definition
eccentric contratcion followed immediately by concentric contraction
prestetch (eccentric) before concentric muscle action= concentric greater force
SEC (series elastic)- stores energe when stretched=elastic recoil effect
muscle spindle- activates stretch reflex When a muscle lengthens, the muscle spindle is stretched and its nerve activity increases. This increases alpha motor neuron activity, causing the muscle fibers to contract and thus resist the stretching. A secondary set of neurons also causes the opposing muscle to relax. The reflex functions to maintain the muscle at a constant length |
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Definition
| delay between arrival of neural stimulus and tension dvlpmt in muscle around 20-100 msec needed to stretch SEC (shorter time in FT fibres) |
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Term
| how measure muscular strength |
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Definition
max torque generated by an entire muscle GROUP at a joint
T=F (distance perep aka moment arm)
divided into parallel force to the long axis (stabilizing or dislocating component)
-one force perpendic to bone (rotational) (perpen makes movement) |
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Term
| 2 factors for muscle strength |
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Definition
tension-generating capability
-affected by corss-sectional area (90N/cm2)
-training state (first 12 weeks improved innervation)
moment arm of contributing muscles
-affected by distance from attachmt and axis of rotation at joint centre
-also angle of muscle attchmt to bone
--greatest torque- by max tension in a muscle 90 deg angle to bone and attached attached far from joint centre as possible |
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Term
| factors for muscular power |
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Definition
product of muscular force and velocity of musc shortening
-rate of torque productionn at a joint
max power~ 1/3 max velocity, and 1/3 max concentric force
-affected by both musclar strength and movement speed |
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Term
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Definition
ability to exert tension over time
tension can be constant (iron cross) or vary cyclically (running)
-affected greatly by force and speed
training- high rep low weight |
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Term
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Definition
exercise induced reduction in the maximal force capacity of muslce
-opposite of endurance
characeristics=
-reduction in force production
-reduction in shortening velocity
-prolonged relaxation of motor units between recruitment |
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Term
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Definition
| sensory receptor- provokes reflex contraction in stretched muslce, inhibits tension dvlpnt in antagonist muslces |
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Term
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Definition
| monosynaptic reflex initiated by stretching of muscle spindles and resulting in immediate dvlpmt of muscle tension |
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Term
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Definition
| angle thru which joint moves from anatomical position to the extreme limit of segment motion in a particular direction |
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Term
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Definition
muscle unable to dvlp tension when stimulated by it's motor axon
resistance SO>FOG>FG (slowoxi...)
causes:? decreased rate of intracellular Ca release
-reduced uptake of Ca by SR |
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Term
| effects of muscle temperature |
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Definition
higer temp- increas speed of nerve and musc function
-shifts the F-V curve up
=higher max.isometric tension and velocity of shortening
-fewer motorunits needed to sustain a given load
-metabolic processes quicken
=increased musc strength, power and endurance |
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Term
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Definition
| overstretching of musc tissue- mild, mod, and severe |
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Term
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Definition
| muscle bruises - can lead to myositis ossificans (calcification of muscle) |
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Term
| other common musc injuries |
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Definition
cramps
DOMS delayed -onset muscle soreness
compartment syndrome-limb threatening and life threatening condition, defined as the compression of nerves, blood vessels, and muscle inside a closed space (compartment) within the body.[1] This leads to tissue death from lack of oxygenation due to the blood vessels being compressed by the raised pressure within the compartment. |
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