Biomechanics Jan 21

Question 1

Why is a tendon equally as important as a muscle?

Answer 1

force transmitter

Question 2

What is considered the force generator/contraction piece vs force transmitter/elastic component in MTU?

Answer 2

muscle

tendon

Question 3

How do muscles differ in terms of 6 functions?

Answer 3

a. fibre L
b. Pennation angle
c. tendon L
d. fibre type
e. moment arm
f. site - mass/anatomic CSA

Question 4

What two components make up the physiologic PSA

Answer 4

fibre length
pennation angle

Question 5

Architecture of a muscle usually relates to what two things?

Answer 5

position in body
function

Question 6

Describe the m fibre length and number related to muscles of the core

Answer 6

short m fibres
++ number to create large PSA, key for stability

Question 7

Describe the m fibre length and number related to muscles of the proximal limb

Answer 7

hip/sh
huge AROM: long fibres, free tendon short as driven by contraction element > elastic

Question 8

Describe the m fibre length and number related to muscles of the distal limb

Answer 8

longer tendon, contraction element of muscle located proximally
lightens mass to increase efficiency and movement, therefore short m fibres and longer tendon –> big force generating capacity and elastic secondarily by tendons

Question 9

Axial muscles generally act as ___

Answer 9

stabilizers

Question 10

Proximal limb muscle generally have __ m fibre, __ free tendon and mixed fibre type for __ production

Answer 10

longer
moderate\muscle

Question 11

Axial m: __ muscle fibre, ___ fre tendon, ___ resistant fibres

Answer 11

shorter
minimal
slow

Question 12

Distal muscles: __ m fibre, __ free tendon, mixed fibre type for __ production and __ control

Answer 12

moderate
long
force
fine

Question 13

What is the smallest unit of the muscle/force generator

Answer 13

sarcomere

Question 14

How does a sarcomere generate force?

Answer 14

cross bridge formation due to actin and myosin
myosin head connects with actin through calcium

Question 15

How much F does one sarcomere/independent stroke perform? How many m does it shorten?

Answer 15

picoN
picoM

Question 16

What influences the force of the sarcomere?

Answer 16

capacity of sarcomere to form due to force-L relationship, force-velocity relationship

Question 17

What is the force-L relationship in terms of myosin and actin

Answer 17

overlap of these two and space for cross bridge to form –> at shorter length - overlap of actin decreases force vs at length, gap between actin and myosin means not enough cross bridges form and decrease of force

Question 18

How does the force-v relationship vary in terms of ability to produce force?

Answer 18

muslce shortens quickly - generates little force
increases force when the muscle lengthens and stretch of cross bridge get some increased force

Question 19

When does a sarcomere generate its highest level of force ?

Answer 19

slowly
close to resting length

Question 20

What makes up the elastic/passive element of the MTU?

Answer 20

how much force from aponeurosis and tendon - made of cllagen

Question 21

Increase in tendon stretch means ___ in force

Answer 21

increase

Question 22

As muscle length increases, passive force __, active force rapidly __ to MTU and becomes unstable

Answer 22

increase
decreases

Question 23

Concentric m: how does this generate force as compared to R, and does the unit shorten or lengthen?

Answer 23

greater force than R to create movement

shortens

= power production

Question 24

Eccentric m: how does this generate force as compared to R, and does the unit shorten or lengthen?

Answer 24

Resists movement
MTU generates force < R to movement and lengthens

= E absorption

Question 25

If the muscle has greater stiffness than the tendon, how do these components move when a force is applied?

Answer 25

muscle static, tendon lengthens

Question 26

What does muscle stiffness depend on?

Answer 26

how much force m generating --> how much activated, length, contraction and velocity within which it is changing length

Question 27

What does tendon stiffness depend on?

Answer 27

property of tendon only

Question 28

Do muscle fasicles change with tension the same way?

Answer 28

no, different and different from tendon

Question 29

Ex of m fasicles vs tendon vs MTU - gastroc/distal limb running. How do these change in relation to force?

Answer 29

MTU and tendon similar in terms of dorsi/PF changes vs m fasicles shorten slowly throughout entire phase until end where increase speed (slow concentric contraction in stance) This indicates efficiency of the tendon

Question 30

In a countermovement jump, generation of an impulse against the ground depends on which two things?

Answer 30

take off v when feet leave the ground which depends on COM tarvel from take off to max height at centre of jump

Question 31

CM jump: m of lower limb needs to generate __ force against ground and then change ? in order to extend jointb of lower limb

Answer 31

large length

Question 32

A running jump which translates horizontal kinetic E to vertical __ time on the ground to conserve E

Answer 32

decreases

Question 33

Maximum force of contractile element in concentric contraction is achieved at __ shortening velocity

Answer 33

slow

Question 34

Power depends on __/__

Answer 34

force x velocity or work/time

Question 35

Max power at __ load: ___ shortening and __ load = high force

Answer 35

low rapid low

Question 36

Elastic element: tendon to amplify shortening velocity to allow...

Answer 36

high activity

Question 37

If muscles are bad at producing force at fast speeds, what can help to produce the highest force before activating the tendon

Answer 37

pre activation of muscle tends to help ie sprint start