Types of Muscle Fibre

Question 1

What are the 3 types of muscle fibre?

Answer 1

• Type 1 (slow twitch)
• Type 2a (fast oxidative glycolytic) - FOG
• Type 2b (fast twitch glycoltic) - FTG

Question 2

What are the average proportions of fast to slow twitch muscles?

Answer 2

50/50 and can be slightly affected by training

Question 3

Name a type of sport associated to each muscle fibre…

Answer 3

• Type 1 = 100m (sprint)
• Type 2a = game play or 400m (lactic acid system)
• Type 2b = marathon (aerobic)

Question 4

Name 5 characteristics of slow twitch muscle fibre…

Answer 4

• Slow contraction time
• Used for low intensity and long endurance work (High aerobic capacity)
• Low motor unit size (10-180) as the contractions not as powerful
• High myglobin levels
• High mitrochondria levels
• Red in appearance (oxygenated)

Question 5

Name 5 characteristics of fast oxidative muscle fibre…

Answer 5

• Fast contraction time
• High intensity endurance events (400m swim) - lactic acid system
• Medium aerobic capacity, high anaerobic capacity
• High motor unit size (300-800)
• Possess large stores of glycogen and glycolytic enzymes (PFK) for the lactic acid system

Question 6

Name 5 characteristics of fast twitch G muscle fibre…

Answer 6

• Fast contraction time
• Best for explosive events (shot putt)
• Low aerobic capacity, very high anaerobic capacity
• Increased sarcoplasmic volume (larger diameter to produce greater movement - thicker myosin)
• Large stores of PC - increasing the potential for short term regeneration of ATP

Question 7

Why does hypertrophy occur?

Answer 7

• After power and strength training = increase size and number of myofibrils, increased sarcoplasmic volume and increased myosin size
• After endurance training = increased capillarisation, increased number and size of mitrochondria, increased myglobin stores

Question 8

How does endurance training affect muscle fibres?

Answer 8

• can turn small % of FTG to FOG

- an excess of training can lead to loss of speed

Question 9

How does weight training affect muscle fibres?

Answer 9

needs tetanic contraction for max contraction to engage as many motor units as possible with high resistance and low repetition and so develop max strength