B4 + B5 - Muscle fibres

Question 1

What are the three types of muscle fibre?

Answer 1

• type 1
• type IIa
• type IIx

Question 2

What are the characteristics of type 1?

Answer 2

• aerobic respiration
• slow twitch
• low power output
• very slow to fatigue
• high number of mitochondria
• suited to marathon running

Question 3

What are the characteristics of type 2a?

Answer 3

• fast twitch
• good power output
• fatigues quickly
• low number of mitochondria
• anaerobic respiration
• suited to 200-400 meters

Question 4

What are the characteristics of type 2x?

Answer 4

• extremely fast twitch
• very high power output
• fatigues very quickly
• low number of mitochondria
• anaerobic respiration
• suited to 100 meters

Question 5

What are mitochondria?

Answer 5

• this is the site within muscle cells where respiration occurs (either aerobic or anaerobic)
• more mitochondria = better ability to utilise oxygen when exercising
• energy is created using glucose within these mitochondria

Question 6

Can you change the mix of type 1, 2a and 2x fibre types in your muscles?

Answer 6

• no, each person is different (even brothers and sisters)
• within each person, the different muscle groups also have different concentrations of each type (e.g. legs may have high 1, arms may have higher 2a)
• the percentage of fibre types you have is set and it is based on your genetics and the number/ concentration of each muscle fibre type cannot be altered
• BUT through effective training the effectivity of each muscle type can be drastically improved

Question 7

Two real life examples in sports performers of fibre types effecting their performance.

Answer 7

Usain Blot - genetics have given him a very high concentration of 11x compared to other people
Mo Farah - genetics and training have meant his type 1 fibres are exceptionally efficient

Question 8

What is a isometric muscle contraction?

Answer 8

• the length of a muscle does not change and the joint angle does not alter
• the muscle is actively engaged in holding a static position

Question 9

Examples of isometric muscle contraction?

Answer 9

• abdominal plank position
• wall sit (quadriceps)
• this type of muscle work is easy to undertake but rapidly leads to fatigue = it can cause sharp increases in blood pressure as blood flow is reduced

Question 10

What is a concentric muscle contraction?

Answer 10

• tension rises to meet resistance, remains stable as muscle shortens

Question 11

Examples of concentric muscle contraction.

Answer 11

• upwards phase of a bicep curl (bicep brachii)

Question 12

What is a eccentric muscle contraction?

Answer 12

• contraction when muscle returns to it’s normal length after shortening against resistance (under strain)
• contracting and lengthening (thinner)

Question 13

Examples of eccentric muscle contraction.

Answer 13

• bicep curl in the controlled downwards phase (bicep brachii)

Question 14

What is the aim of putting strain/ pressure on the muscles (simply)?

Answer 14

muscle micro-tares = DOMS = muscle growth