Week 2 (part a)

Question 1

Muscle contraction and relaxation involves several steps between depolarisation of the ______ and cross bridge attachment involving ___ and ___

Answer 1

a-motor neuron, myosin and actin

Question 2

Strength is a function of the number of sarcomeres and muscle fibres in _____, which explains why strength is related to the cross sectional area of a muscle.

Answer 2

parallel (not in series)

Question 3

Following puberty, ____ muscle mass percentage increases more than ___% from testosterone

Answer 3

boys, 10% (Total 53%)

Girls stays the same at 42%

Question 4

Despite the dimensional theory stating exponent should be 2.0, a study showed that in schoolboys it was much lower/higher?

Answer 4

higher - Average over 3.0

Question 5

Factors influencing strength (5)

Answer 5

• Muscle length
• Contraction velocity
• Motor unit type (faster usually stronger)
• Muscle architecture
• Type of contraction (strength higher when lengthening not shortening)

Question 6

Nerve conduction velocity is….

Answer 6

The speed at which motor and sensory impulses transverse a given section of nerve (m/s)

Question 7

Nerve conduction velocity is influenced by…. (4)?

Answer 7

• axonal diameter
• local tissue temperature
• age
• height

Question 8

A newborn has how much nerve conduction velocity of an adult?

Answer 8

Half. It increases rapidly the first year of life.

Question 9

There is an increase in nerve conduction velocity between ages 0 - 20 that’s associated with…

Answer 9

age and muscle diameter

Question 10

The level of force of a motor unit can be varied by changing…?

Answer 10

• The number of MUs recruited

- The firing rate of a-motor neurons

Question 11

Some evidence suggests a lower amount of type ____ fibres in children

Answer 11

Type II

Question 12

In a review, Dotan et al (2012) hypothesised that children …… type II motor units to the extent typical adults do

Answer 12

do not fully recruit or fully optimise use of type II fibres

Question 13

The increase in muscle cross sectional area with age (until about age 20-25), is linked not to the _____ but rather _____

Answer 13

the number of fibres but rather the type of fibre (slow twitch decreases and fast twitch increase).

Question 14

At age 5: Approx ___% fast twitch fibres

Answer 14

35%

Question 15

At age 30: Approx ___% fast twitch fibres

Answer 15

50%

Question 16

From a young child to adulthood, the amount of antagonist force increases/decreases

Answer 16

decreases (while agonist force increases)

Question 17

Blimkie (1989) reported that motor unit activation for knee extensors was significantly higher in younger/older?

Answer 17

older (teens) vs younger (child)

Question 18

The number of neurons present by early adulthood already exist at birth/early infancy (T/F)

Answer 18

True

Question 19

Muscle damage releases what into the bloodstream?

Answer 19

creatine kinase

Question 20

Children appear to have less/more muscle damage compared to adults post exercise

Answer 20

less

Question 21

Is the development of strength in growing children linked to muscle cross-sectional area?

Answer 21

Somewhat but not all strength

Question 22

Is the development of strength in growing children linked to nerve conduction velocity?

Answer 22

At some level, yes

Question 23

Is the development of strength in growing children linked to recruitment of type II motor units?

Answer 23

In theory yes, but lacks evidence

Question 24

Is the development of strength in growing children linked to the transformation of type I to type II fibres?

Answer 24

Some evidence for it

Question 25

Is the development of strength in growing children linked to agonist-antagonist co-contraction?

Answer 25

may contribute but most evidence is for dynamic contraction and seems to be less evidence for isometric contraction

Question 26

Is the development of strength in growing children linked to central inhibition?

Answer 26

Some evidence in young children

Question 27

Children gain isometric and isokinetic strength as they grow due to …?

Answer 27

Muscular enlargement (fibre hypertrophy)