Strength and power

Question 1

Give 3 functions of muslces

Answer 1

Heat production , protection, force production

Question 2

Name and describe the 5 roles of muscles

Answer 2

Agonist = prime mover, responsible for creating movement
Assistant/secondary movers = muscles that produce the same movement as the agonist
Antagonist = muscle which opposes the agonist
Synergists = (fixator) muscle that supports a body part to supply a base for another muscle to pull on
Neutraliser = muscle that provides an unwanted action of the agonist

Question 3

What 3 main factors determine muscle function

Answer 3

Fiber length
Pennation angle
Cross-sectional area

Question 4

Name and describe the 3 muscle fiber types

Answer 4

Type 1 (Slow Oxidative) = slow twitch, fatigue resistant, aerobic metabolism, long distance
Type 2 (Fast oxidative glycolytic) = intermediate in characteristics, middle distance
Type 3 (Fast glycolytic) = fast twitch, develop greater force of contraction, fatigue rapidly, anaerobic metabolism, sprint muscle fibers

Question 5

Describe the following terms:
Isometric muscle contraction
Concentric muscle contraction
Eccentric muscle contraction

Answer 5

Isometric =  no movement occurs
Concentric = muscle shortens and produces movement
Eccentric = tension developed resists movement/ lowers body part against gravity

Question 6

How does the force produced by active tension change as muscle length increases?

Answer 6

As muscle length increases, the force produced decreases as the filaments do not overlap, the myosin heads have nothing to attach to and so can not produce tension

Question 7

How does the force produced by passive tension change as muscle length increases?

Answer 7

As muscle length increases, the force produced also increases as the muscles are at rest

Question 8

What is active insufficiency?

Answer 8

The agonist muscle can not shorten beyond a certain limit without losing tension

Question 9

What is passive insufficiency?

Answer 9

When a full range of motion at any joint is limited by the antagonist muscle length

Question 10

When do eccentric muscle contractions create the most force?

Answer 10

Eccentric movements create maximal force at maximal velocity.

Question 11

When do concentric muscle contractions create the most force?

Answer 11

Concentric movements create maximal force at minimal velocity.

Question 12

Describe the oxford scale for strength testing

Answer 12

0 = no muscle activation
1 = trace of muscle activation, such as a twitch
2 = muscle activation with gravity eliminated (performed at 90degrees to gravity)
3 = muscle activation against gravity
4 = muscle activation against small resistance
5 = muscle activation against examiners full resistance

Question 13

What are the benefits of objective measurements of strength and give examples of some

Answer 13

Gives us definitive numbers, not someones opinion
e.g
dynamometers
1 rep max

Question 14

Give the equation for limb symmetry index and explain what results you would expect

Answer 14

LSI =
peak torque in non-dominant limb / peak torque in dominant limb x 100

Should not expect results of more than 15%, if this does occur, patient is at risk of injury

Question 15

Define muscular strength and power and give an example of each

Answer 15

Muscular strength: ability of a muscle to exert maximal force against resistance. e.g a heavy squat performed at a slow speed
Power: ability to produce strength at speed. e. box jump

Question 16

Give an equation for power

Answer 16

Power = force x velocity