1.1a muscle fibre types and contraction

Question 1

fast glycolytic

Answer 1

-large PC stores for ATP-PC system
-largest amount of force
-anaerobic exercise - high intensity (100m sprint)

Question 2

fast oxidative glycolytic

Answer 2

-produce large amount of force quickly
-resist fatigue
-high intensity work lasting several mins

Question 3

slow oxidative

Answer 3

-myoglobin transports oxygen to mitochondria
-mitochondria processes oxygen into energy
-works aerobically
-produces small amounts of force over a long period of time
resistant to fatigue - endurance events (10000m)

Question 4

how long do SO muscle fibres take to recover

Answer 4

each fibre recovers quickly and available for recruitment in 90 seconds

Question 5

work relief ratios for SO fibres

Answer 5

low aerobic work relief ratios
1:1 work:relief

Question 6

how often can aerobic activity be performed for SO fibres?

Answer 6

doesn’t cause damage so daily basis

low-intensity use of SO recommended after heavy weight training to increase blood flow and enhance healing

Question 7

when are FG fibres recruited

Answer 7

in last 2-20 seconds of muscle contraction, near exhaustion or when maximal efforts are required

followed by DOMS 24-48 hours later

Question 8

how long do FG take to recover

Answer 8

need much longer to recover than SO
take 4-10 days to recover after exhaustion

leave 48 hours before using same muscle group again

Question 9

when are FG fibres recruited

Answer 9

in last 2-20 seconds of muscle contraction, near exhaustion or when maximal efforts are required

followed by DOMS 24-48 hours later

Question 10

work:relief ratio FG fibres

Answer 10

high work:relief ratio 1:3+

3-5 mins rest between sets of 2-6 reps

Question 11

when do muscles contract?

Answer 11

when stimulated by an electrical impulse

Question 12

where is an electrical impulse sent from?

Answer 12

central nervous system

Question 13

what is a motor neuron

Answer 13

a specialised cell that transmits nerve impulses rapidly to a group of muscle fibres

they have a cell body in the brain/spinal cord and axon that branches to connect motor end plates to muscle fibres

Question 14

what is a motor unit

Answer 14

the motor neuron and its muscle fibres

carries nerve impulses from brain and spinal cord to muscle fibres - initiates muscular contraction

Question 15

what is a neurotransmitter

Answer 15

a chemical (acetylcholine) produced and secreted by a neuron which transmits the nerve impulse across the synaptic cleft to the muscle fibre

Question 16

when is the neurotransmitter used?

Answer 16

when the action potential needs to cross the synaptic cleft

Question 17

what is an action potential?

Answer 17

positive electrical charge inside the nerve and muscle cells that conducts the nerve impulse down the neuron and into the muscle fibre

Question 18

when is an action potential created?

Answer 18

when enough of the neurotransmitter is secreted and the electrical charge is above the threshold

Question 19

what is the all-or-none-law?

Answer 19

whether the stimulus is above a threshold, all muscle fibres will give a complete contraction or none at all

Question 20

process of muscle contraction

Answer 20

1. nerve impulse initiated by the motor neuron cell body
2. nerve impulse conducted down the axon of motor neuron by nerve action potential to synaptic cleft
3. acetylcholine (neurotransmitter) secreted into synaptic cleft to conducted nerve impulse across the gap
4. if the electrical charge is above a threshold, the muscle fibre will contract
5. happens in an all-or-none fashion

Question 21

small motor units and muscle fibre type for activity

Answer 21

small motor units stimulate relatively small muscle fibres

motor unit produces low and slow amount of force over a long period of time
-resists fatigue

good for sustained muscular contraction eg maintenance of posture

Question 22

large motor units and muscle fibre type for activity

Answer 22

large motor neurons stimulate many muscle fibres

creates a motor unit which produces a large amount of force rapidly
-fatigues quickly

good for brief exertions of large force
eg jumping, throwing