MOd 8

Question 1

4 factors affect force prod

Answer 1

muscle architech
- PCSA
- fibre type
- arrangement

neural drive
- rate and recruitment

force length relationship
- active and passive components
- overlap

force velocity relationship
- for concentric actions, higher velocities = lower force
(for eccentric, compared to isometric, force prod is higher 150% then levels off)

Question 2

describe all aspects of force velocity curve

Answer 2

max iso contract = 0 velocity

• for concentric, force decrease exponentially as velocity increase
• for eccentric, can get exponentially more force prod (150%) until about a couple percent of max contractile velocity, then flattens out

Question 3

what must be known to estimate muscle length

what is the equation for finding length of non-right angle triangle

Answer 3

• we will always know a and b because they are constant (insertions of tendon)
• must know theta (joint angle)
• trying to find “l” (muscle length)

equation: l^2 = a^2 + b^2 - 2ab * cos(theta)

Question 4

how would you describe graph of joint angle at -1 degrees per second against time

how would the angular velocity look graphed against time?

how would this graph look for muscle length graphed against time? How about muscle velocity?

Answer 4

linear negative sloping line

flat (horizontal line)

downward curve that levels off and almost starts to curve back up (because angular velocity is constant but there is more linear distance that the muscle lengthens when the muscle is more perpendicular to the attachment joint.

slight inverted U

Question 5

name some uses for this type of biomechanics

Answer 5

• can decide where is best place to attach tendon during surgery
• …?