1. (8) Energy systems in muscle cells
(A)
Creatine Phosphate
(B) Lactic Acid Metabolism
(C)
Types of skeletal muscle fibres

2. (c) Energy systems in muscle cells
State the 2 types of skeletal muscle fibres
Identify the differences between the 2 types of skeletal muscle fibres:
Contraction speed
Activities most suited to muscle fibre
How they generate ATP
Number of mitochondria present
Blood supply
Concentration of myoglobin in cells
Storage fuel
State the difference between the skeletal muscle fibres found in an athlete and a non-athlete

3. Where are the muscle fibres?

4. Do you think these athletes have the same type of muscle fibres?
No, they don’t!
One has more SLOW TWITCH muscle fibres, whilst the other has more FAST TWITCH muscle fibres.

5. Slow twitch vs. Fast twitch
For each athlete, think about:
What type of muscle fibre they might have MORE of
The sport they compete in
The energy they need for their sport

6. Slow twitch vs. Fast twitch

7. Tasks: Create a table to compare the all the differences between the 2 types of muscle fibres based upon the information on the following page. Think about suitable headings (look to your LEARNING OUTCOMES if you are very stuck!)

8. Slow Twitch Muscle Fibres Fast Twitch Muscle Fibres
Differences
Slow Twitch Muscle Fibres
Fast Twitch Muscle Fibres
Contraction speed
Activities most suited to muscle fibre
How ATP is generated
Number of mitochondria present
Blood supply
Concentration of myoglobin in cells
Storage fuel

9. Slow twitch (Type 1) muscle fibres contract more slowly, but can sustain contractions for longer and so are good for endurance activities. Fast twitch (Type 2) muscle fibres contract more quickly, over short periods, so are good for bursts of activity.
Slow twitch muscle fibres are good for endurance activities like long distance running, cycling or cross-country skiing. Slow twitch muscle fibres rely on aerobic respiration to generate ATP and have many mitochondria, a large blood supply and a high concentration of the oxygen storing protein myoglobin. The major storage fuel of slow twitch muscles fibres is fats.
Fast twitch muscle fibres are good for activities like sprinting or weightlifting. Fast twitch muscle fibres can generate ATP through glycolysis only and have few mitochondria and a lower blood supply than slow twitch muscle fibres. The major storage fuels of fast twitch muscles fibres are glycogen and creatine phosphate.

10. Comparing athletes and non-athletes
Most human muscle tissue contains a mixture of both slow and fast twitch muscle fibres.
Athletes show distinct patterns of muscle fibres that reflect their sporting activities.

11. Tasks: Use the information in Figure 1 to:
Approximately 50% slow twitch and 50% fast twitch
Sprinters contain around 80% fast twitch and 20% slow twitch, middle distance runners contain around 60% slow twitch and 40% fast twitch, marathon runners contain 80% slow twitch and 20% fast twitch. As the distance increases the proportion of slow twitch muscle fibres increases and slow twitch muscle fibres decrease or vice versa.
Use the information in Figure 1 to:
describe the muscle composition of a normal active person
describe how muscle composition differs in athletes covering short, middle and long distances.

12. (c) Energy systems in muscle cells
State the 2 types of skeletal muscle fibres
Identify the differences between the 2 types of skeletal muscle fibres:
Contraction speed
Activities most suited to muscle fibre
How they generate ATP
Number of mitochondria present
Blood supply
Concentration of myoglobin in cells
Storage fuel
State the difference between the skeletal muscle fibres found in an athlete and a non-athlete

13. You have now finished unit 1 (and HALF of your course!) 