Factors affecting muscle strength

Question 1

muscle strength

Answer 1

is the ability of skeletal muscle to develop force for the purpose of providing stability and mobility within the musculoskeletal system so that functional movement can take place

Question 2

examples of muscle strength

Answer 2

Capacity to exert force

Ability to do work against resistance

Question 3

importance of muscle strength

Answer 3

activities of daily life (ADL)
Lifespan - high muscular strength = reduced risk of premature death
Sports - higher muscular strength = better performance and reduce risk of injury

Question 4

where does the muscle strength come from

Answer 4

muscle tension

Question 5

load

Answer 5

The force exerted on the muscle by the object

Question 6

muscle tension

Answer 6

Force developed in a contracting muscle when the muscle acts on an object

Question 7

active tension

Answer 7

Tension developed by the contractile elements of the muscle

Question 8

passive tension

Answer 8

Tension developed by stretching the non-contractile elements of the muscle
Elasticity

Question 9

contractile compenents contribute to muscle tension

Answer 9

myosin and actin overlapping

Question 10

elastic compenents contribute to muscle tension

Answer 10

epimysium of muscle

tenons

Question 11

torque

Answer 11

The capability of a force to produce rotation

Question 12

moment =

Answer 12

Force x Perpendicular Distance from the line of action of the force to the centre of rotation of the object

Question 13

first class lever

Answer 13

chin raise

Question 14

fulcrum of chin raise

Answer 14

atlas and occipital bone of skull

Question 15

effort of chin raise

Answer 15

neck pull posterior muscles of skull down

Question 16

lead of chin raise

Answer 16

anterior skull is lifted

Question 17

second class lever

Answer 17

calf raise

Question 18

fulcrum of calf raise

Answer 18

joints at the ball of foot

Question 19

effort of calf raise

Answer 19

calf muscles contract and lift muscle weight

Question 20

lead of calf raise

Answer 20

body weight

Question 21

third class lever

Answer 21

elbow flexion

Question 22

effort of elbow flexion

Answer 22

bicep contract and pull forearm up

Question 23

lead of elbow flexion

Answer 23

forearm and hand we lift

Question 24

fulcrum of elbow flexion

Answer 24

elbow joint flexes and bicep contract

Question 25

factors affecting muscle strength

Answer 25

``` Integrity of connective tissue and bone Type of muscle contraction Length of muscle Speed of contraction Number and size of motor units activated ```

Question 26

muscle force will be inhibited by

Answer 26

Pain Inflammation Injury Disease of the connective tissue or bone upon which the muscle acts

Question 27

Direction of muscle forces wrt joint angle in a concentric movement

Answer 27

the same direction

Question 28

Direction of muscle forces wrt joint angle in eccentric movement

Answer 28

the opposite direction

Question 29

Source of force producing movement in concentric contraction

Answer 29

Muscle itself (muscle torque > load)

Question 30

Source of force producing movement in isometric contraction

Answer 30

Muscle and load are equal and opposite (muscle torque = load)

Question 31

Source of force producing movement in eccentric contraction

Answer 31

External load or gravity (muscle torque < load)

Question 32

purpose of concentric contraction

Answer 32

To generate force against external resistance; to create movement against gravity

Question 33

purpose of isometric contraction

Answer 33

To maintain stability

Question 34

purpose of eccentric contraction

Answer 34

To control downward movement; to slow down a very fast movement

Question 35

If muscle shortening (concentric contraction) is preceded by an eccentric muscle action, what does this mean? And why?

Answer 35

the resulting concentric action is capable of generating greater force. Because a stretch in a muscle increases its tension by storing potential elastic energy in the series elastic component of the muscle.

Question 36

length tension relationship in short lengths

Answer 36

When a muscle has shortened to half its length, the filaments have exceeded their overlapping capability and fewer cross bridges can be formed.

Question 37

length tension relationship in long lengths

Answer 37

When the muscle is lengthened > 20% beyond its resting length, cross bridges slip past one another and fewer cross bridges can be formed

Question 38

length tension relationship in optimal length

Answer 38

Optimal length is slightly longer than resting length because Contractile components are optimally producing tension (lots of cross bridges available) Passive components are optimally storing elastic energy

Question 39

Muscles create an active force which will:

Answer 39

Match the external load (object or gravity) | Adjust the speed of movement

Question 40

in concentric action how does the velocity and force change?

Answer 40

In concentric action, velocity increases at the expense of a decrease in force.

Question 41

In concentric action, velocity increases at the expense of a decrease in force. Why?

Answer 41

Because as the velocity of muscle shortening increases, the cycling rate of cross-bridges increases, leaving fewer cross-bridges attached at one time.

Question 42

motor unit

Answer 42

a single motor neuron and all the muscle fibres it innervates

Question 43

hennemann size principle

Answer 43

Smaller motor units are recruited first, then larger ones | Slower twitch muscle fibres are recruited first, then faster twitch fibres

Question 44

rate coding

Answer 44

Muscle contracts by the summation of twitches Rate coding means: Higher frequency = higher force

Question 45

how are skeletal muscle fibres classified

Answer 45

slow twitch (type 1) or fast twitch (type 2)

Question 46

3 types of skeletal muscle fibres

Answer 46

``` Type I - Slow twitch oxidative (S) Type IIA (2a) - Fast twitch oxidative-glycolytic (FFR = fast fatigue resistant) (fast twitch) Type IIX (2b) - Fast twitch glycolytic (FF = fast fatiguing) (super fast twitch) ```

Question 47

fusiform muscle

Answer 47

=> rapid shortening, greater ROM, less force

Question 48

pennation muscle

Answer 48

slower velocity, less ROM, greater force and power (greater CSA)