week 12 Flashcards
(48 cards)
after eccentric exercise there is a disruption in _____
z discs
coordination of muscle force dictate ___ and ___ of the movement
quality and quantity
why do we care about skeletal muscle and joint mechanics
- predicting injury and performance
- biomechanical modelling
- understanding disease processes
- fundamental science - how muscle works
start at the sarcomere and end at the muscle
sarcomere –> myofibril –> muscle fibers –> fascicles –> muscle
how are sarcomeres arranged
longitudinally or in series
how does light defraction allow us to determine and measure sarcomere length
light can travel through the I band and the size of the I band changes with length so the defraction pattern will change
why do we want to measure sarcomere length
sarcomere length influences cross bridge binding by the overlap between actin and myosin and is defined by sarcomere length
this relationship is important for the force length relationship
what do muscles always want to do
bring the z-discs together
true or false all muscles act at an optimal length
false
why dont all muscles act at an optimal length
to balance force generation capabilities around a joint (the muscles around a joint must be balanced to act as a joint system)
what is passive force
restorative force due to the stretch of muscle to pull back towards the center
true or false all sarcomeres are the same length
false
what is the scaffolding of muscles primarily and why
collagen it is very still so it resists and is the main contributor of passive force in muscle
as stress increases so does
strain
what to we measure to measure optimal force production in the force length relationship
the plateau of force
why does it become harder to understand the force-length experiment the more it continues to lengthen
- passive force is generated
- the force transducer can’t tell or differentiate between active and passive forces produced
how do you account for passive force during the force-length experiment
stretch the muscle then measure the force before stimulation to get the passive tension
draw the force velocity relationship and explain it
what were the 2 methods for the force-velocity experiment
constant velocity and constant force
what was the constant velocity method in the f-v experiment
stimulate muscle and then shorten or lengthen the muscle at a constant velocity and re cord the force required to produce this shortening or lengthening
what is the constant force method for the force velocity experiment
stimulate muscle and then rapidly decrease or increase the force to a constant level and record the subsequent velocity of shortening or lengthening
how would the axis work for the force, length and velocity graph
force on y
sarcomere length on x
velocity on z
force is dependent on the…
instantaneous velocity and length of a muscle
true or false just because a joint is being held isometrically it does not mean the muscle isn’t changing length
true since the tendon is getting longer, muscle is shortening
