Anatomy muscles

Question 1

What is the meaning of contraction with regards to muscles

Answer 1

Active muscle - not necessarily shortening

Question 2

How does force generated during concentric contraction compare to isometric or eccentric contraction?

Why?

Answer 2

Less force

1. Non contractile elements of the muscle will offer resistance to active shortening (similar to pressure when pushing a syringe)
2. Actin binding sites are moving past the myosin cross bridges and it takes a certain amount of time to attach and detach. Therefore number of cross bridges and force generation is less

Question 3

How does energy cost of concentric contraction compare to isometric contraction and why?

Answer 3

Higher energy cost (and heat production) from concentric contraction

Due to rapid cycling of cross bridges

Question 4

How does force production in eccentric contraction compare to isometric and concentric?

Why?

Answer 4

Higher force production

Tension generated is increased by additional elastic force created by stretch of neck of myosin molecule

Question 5

How does the energy cost of eccentric contraction compare to isometric and concentric contraction?

Why?

Answer 5

Lower energy cost.

When myosin is pulled away from the actin filament it is in the correct position for reattachment and does not require energy to move.

Question 6

How does muscle fatigue, pain and damage in eccentric contraction compare to isometric and concentric contraction?

Why?

What is this called?

Answer 6

Greater due to the potential mechanical damage

DOMS

Question 7

What is the method of observing the extent of muscle activation?

Answer 7

EMG (electromyography)

measures electrical activity stimulating muscle fibres via the motor unit.

Question 8

What is the “group action of muscles”?

Answer 8

For a muscle to work effectively, other muscles must contract to improve the quality of movement

Question 9

Types of muscle roles in the group action of muscles

Answer 9

Prime movers (agonist)
Assistant (synergist)
Stabilisers (fixators)
Antagonists
Spurt
Shunt

Question 10

What is/are the prime mover(s)?

Example?

Answer 10

Muscle(s) playing a major role in initiating, carrying out and maintaining a movement

Brachialis in elbow flexion

Question 11

What are the assistant movers?

Example?

Answer 11

Generate a similar movement to the prime mover but provide a less significant role

Biceps brachii in elbow flexion

Question 12

What are stabilisers/fixators?

Example?

Answer 12

Contract to control the position of a bone so that it can act as a stable base on which the agonists can act.

e.g. lower fibres of trapezius, serratus anterior and rhomboids hold the scapula so that upper attachment of biceps is fixed in elbow flexion

Question 13

What are synergists?

Example x 2?

Answer 13

Muscles that act simultaneously with one or more muscles to help the agonist perform a better movement

e. g. adductors and abductors in hip contract together to prevent sideways movement during hip flexion
e. g. long finger flexors are agonists which grip a ball but they are also wrist flexors. Wrist extensors contract at the same time to prevent wrist flexion

Question 14

What are antagonists

Answer 14

Muscles which act in direct opposition to movement of the joint

Question 15

How do antagonists generally act when agonists are activated?

What is the term for this?

What is an exception to this?

Answer 15

Relaxed

Reciprocal inhibition

Co-contraction

Question 16

What are the benefits of co-contraction?

Example?

Answer 16

Improve joint stability (a form of synergy)

Injury prevention e.g. hamstring slowing leg towards end of range of motion when kicking

Question 17

What are spurt muscles?

How does it impact on their action?

Example?

Answer 17

Fixed point of attachment far from the joint, mobile point of action close to the joint.

Generate a large swing component

e.g. brachialis

Question 18

What are shunt muscles

How does it impact on their action?

Example?

Answer 18

Fixed attachment close to a joint, mobile attachment far from joint

Large amount of compression with a small swing component. Therefore maintain joint stability

e.g. brachioradialis

Question 19

Definition of closed vs open kinetic chain (or closed/open kinematic system)?

Examples?

Answer 19

Closed kinetic chain is where the distal segment (hand or foot) if fixed e.g. press ups or squats vs dumbbell curl/throwing/kicking a ball

Question 20

What is the strength-shortening cycle?

What type of training does this form the basis of?

Answer 20

Where an eccentric contraction precedes an concentric one - believed that this utilises energy stored during the eccentric activity, increasing mechanical efficiency.

Plyometrics

Question 21

Explanation of plyometric training

Answer 21

Muscles pre-loaded by an eccentric contraction followed by concentric contraction increasing muscle force and rate of force development

Question 22

What is the aim of plyometric training?

Answer 22

Adaptations of muscle fibre type and activation profiles

Question 23

What factors determine the magnitude of muscle force?

Answer 23

1. The number of active muscle fibres
2. The muscle fibre type
3. whether the contraction is concentric, eccentric or isometric
4. Starting length of the muscle
5. The speed of contraction
6. The degree of pre-stretch of the muscle

Question 24

What is an apneurosis?

Answer 24

Flat tendon