Muscle Control & Recruitment - Lecture 28

Question 1

How does Muscle Contraction work?

Answer 1

Action potential and resultant contraction

Question 2

Multiple Impulses sent?

Answer 2

A wave summation occurs; multiple increasing frequencies of signal

Question 3

What’s the result of multiple impulses

Answer 3

Increasing force of contraction with increase in signals

Question 4

What happens when there’s a max amount of signals (Action Potential)

Answer 4

Fused tetanus; signal levels out and no more contractions.

Question 5

Total Muscle Tension

Answer 5

Active + Passive Tension

Question 6

Active Tension

Answer 6

Tension that the muscle creates itself from contraction

Question 7

Passive Tension

Answer 7

Tension created by external force through stretch

Question 8

How can the optimal strength (force production) of a sarcomere be produced

Answer 8

Depends on the resting length of the sarcomere; that produces the most force

Question 9

75%

Answer 9

Muscles are too overlapped; actin cross bridges interfere

Question 10

80-120%

Answer 10

Optimal length of the muscle, to allow to lift the most

Question 11

170%

Answer 11

Forming cross bridges are hard to because they’re too stretched

Question 12

Resting Length of Isometric

Answer 12

Resting length stays the same

Question 13

Muscle tension of Isometric

Answer 13

Peak tension developed

Question 14

Resting length of Concentric

Answer 14

Resting length shortens as muscle squeezes.

Question 15

Increase in muscle tension in concentric caused by?

Answer 15

Before on set of movement

Question 16

Resting length of Eccentric

Answer 16

Muscle Length elongates

Question 17

What happens when resistance is greater than the force of contraction of the muscle

Answer 17

Muscle tear and significant damage

Question 18

Relationship of force output and resistance

Answer 18

Being able to overcome a resistance produces a high force of contraction

Question 19

What is a motor unit?

Answer 19

A neuron and all the muscle fibre that neuron innervates (supply with neurons)

Question 20

Two types of muscle fibre?

Answer 20

Type 1 and Type 2

Question 21

Same Neurons and Muscle Fibres

Answer 21

All muscle fibres innervated by the same motor neuron are same fibre (Must be Type 1 or Type 2 Neuron)

Question 22

How do your muscle fibres generate more force?

Answer 22

Principle of Orderly Recruitment

Question 23

Principle Of Orderly Recruitment

Answer 23

Motor Units are always recruited in the same order

Question 24

What does recruitment in the same order mean?

Answer 24

i.e. all of motor units 1 will be recruited, and then if more force is needed, then all of motor unit 2 will be recruited and so on.

Question 25

How does strength training affect recruitment?

Answer 25

Recruits a great amount of motor units, as well as improve speed of recruitment

Question 26

2 main factors of strong muscle contractions

Answer 26

Frequency of impulses and recruitment of motor units

Question 27

Muscle Fibre Continuum

Answer 27

A scale going from type 1 on one side, type IIa in the middle and Type IIb on the other end.

Question 28

Based on contractile and metabolic properties

Answer 28

How muscle fibre types are identified

Question 29

Type I

Answer 29

Oxidative (aerobic), Slow Twitch Muscles (slowly uses energy)

Question 30

Type IIa

Answer 30

Glycolytic/Oxidative, Fast twitch Muscles

Question 31

Type IIb

Answer 31

Glycolytic, Fast Twitch Muscles

Question 32

Usual composition of Fibre Types

Answer 32

50-50 slow:fast

Question 33

Why do people sometimes have more of one fibre type than the other?

Answer 33

Usually explained by predominant genes

Question 34

Is it possible to fully change from one fibre type to another?

Answer 34

You can't move from one to the other, but you can train to move across the continuum

Question 35

How can muscle fibre composition be measured?

Answer 35

Muscle Biopsy; taking a piece of muscle and analyzing to see what muscle type they have

Question 36

What do the muscle fibre types display under a microscope?

Answer 36

Different sizes and colour for each type. Some people have more of one muscle type over the other.

Question 37

Reason for different colour fibre types?

Answer 37

Presence of myoglobin (O2 carrying) and RBC carrying compounds.

Question 38

Primary fuel of Type I

Answer 38

Lipids

Question 39

High capillary density

Answer 39

Type 1

Question 40

How active is ATPase enzyme in Type I

Answer 40

Very low as it doesn't need to produce a lot of ATP for short periods as Type I is longer periods.

Question 41

Force of Type IIb?

Answer 41

Generates force much more quickly as this is associated with activities needing to produce a lot of force in a short amount of time

Question 42

Anaerobic process and fatigues quicker

Answer 42

Type IIb

Question 43

Major fuel of Type IIb

Answer 43

Creatine Phosphate

Question 44

How active is ATPase enzyme in Type IIb

Answer 44

Very high as it needs to produce a lot of energy in a short amount of time

Question 45

Major Fuel of Type IIa

Answer 45

Glycogen (stored sugar)

Question 46

What does Type IIa possess that the other two don't have simultaneously?

Answer 46

Aerobic and Anaerobic energy generating capabilities

Question 47

How active is ATPase enzyme in Type IIa

Answer 47

Moderately active