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

(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

Where are the muscle fibres?

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.

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

Slow twitch vs. Fast twitch

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!)

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

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.

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.

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.

(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

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