biomechanics muscle mechanics

true or false greater muscular forces decrease the risk of injury

true

what are the factors which affect muscle force production?

neural control, muscle fiber properties, muscle length, muscle cross sectional area, muscle contraction velocity

what is hennemans size principle?

smaller motor units are recruited first and as amount of force increases bigger motor units are recruited 

how are motor units recruited 

slow to fast twitch, smallest to biggest

what is motor unit synchonization?

when two or more motor units fire at the same time

what effect does motor units synchronization have?

increased rate of force development during rapid contractions

what training can help to improve motor unit synchonization?

heavy resistance training, ballistic type movements, stregnth training

what is high levels of motor unit synchonization good for?

greater force output 

what are low levels of motor units synchronization good for?

fine motor control

what happens to firing frequency to generate higher amounts of force?

increases

how does firing rate change with intensity?

increases with intensity

what is co-contraction?

when muscles on opposite sides are activated at the same time

why is co-contraction important?

to maintain joint stabilization and movement control

what muscles have a parallel fiber arrangement?

hamstrings, bicecps 

what muscles have a pennate fiber arrangement?

gastroc, quads

what are the characteristics of parallel fiber arrangement?

arranged side by side, longer, able to shorten quickly

what type of contractions are parallel muscle fibres good for?

high speed

can parallel fibers shorten quickly or slowly?

quickly

how do muscle fibres shorten in a pennate arrangement?

at an angle 

what are the characteristics of pennate muscle fiber arrangement?

shorter fibers , forceful at lower speeds

how do pennate contractions compare to a parallel muscle fiber arrangement?

slower contraction but generate higher force output

why does pennate muscle fiber arrangement mean greater force production?

more muscle fibres are packed in as they are arranged at an angle

what is the general range of fiber length to muscle length ratio?

0.2 to 0.6

what would the fiber length to muscle length ratio be of a short muscle fiber and long muscle?

low ratio

what would the fiber length to muscle length ratio be of a long muscle fiber and short muscle?

high ratio

what fiber length to muscle length ratio would a pennate muscle have?

low

what fiber length to muscle length ratio would a parallel muscle have?

high

why can higher forces be produced at slower velocities?

more time for actin and myosin to form crossbridge