1. Starter Activity Timer
You have 20 minutes to explain the assigned step of the Sliding Filament theory.
Use the success criteria and SWEETS provided
Timer

2. Muscle Fibres Learning Outcomes
All able to remember and understand the 3 different types of fibres
Most are able to apply knowledge of the fibres to sporting events.
Some are able to justify the proportions of muscle fibres in each muscle

3. Homework Answer exam questions 3 & 4 on p42 (sheet from last week).
Using photos from starter activity display this information in a way that you feel is most appropriate to aid revision (flip book, poster, instruction manual)
Complete flipped learning worksheet watching video on weebly.

4. Muscle Fibres
Within skeletal muscle there are 3 types of muscle fibres. All contain a mixture of all three but not in equal proportions.
This mix is mainly genetically determined.
These fibres are grouped into motor units, only one type of fibre can be found in one unit.
(Motor unit – the motor nerve and the group of muscle fibres that it controls)

5. Table of characteristics: Structural
Slow Oxidative Twitch
Type I
Fast Oxidative Glycolytic
(F.O.G.)
Type IIa
Fast Twitch
Glycolytic (F.T.G.)
Type IIb
Structural
Fibres per motor neurone
10-180
Motor neurone size
Small
Large
Myoglobin content
High
Medium
Low
Type of myosin ATPase
Slow
Fast
Mitochondrial density
Capillary density
Sacroplasmic reticulum development
Glycogen stores
In pairs look at homework sheet on characteristics of muscle fibres. Are your answers the same? Justify your decisions.

6. Table of characteristics: Functional
Slow Oxidative Twitch
Type I
Fast Oxidative Glycolytic
(F.O.G.)
Type IIa
Fast Twitch
Glycolytic (F.T.G.)
Type IIb
Force of contraction
Low
High
Speed of contraction
Slow
Fast
Fatigability
Medium
Aerobic capacity
Anaerobic capacity
Motor Unit strength

7. Examiners report Muscles
Questions are frequently asked on the characteristics of muscle fibre types.
If the question asks for fast-twitch characteristics, learn the following as they are probably the most straightforward to remember: low number of mitochondria, low myoglobin, low capillary density, low triglyceride stores, high glycogen stores, high PC stores and low fatigue resistance.
These characteristics can be used for slow-twitch fibres — just reverse them!

8. Muscle fibres
Although fast twitch fibres generate much greater forces they have a higher fatigue index meaning shorter contraction time.
The relative proportion of each fibre type varies in the same muscles of different people.
Elite endurance – greater proportion of slow twitch fibres
Elite sprinter – greater proportion of fast twitch fibres

9. Muscle fibres
Using the sporting pictures create a continuum like the one shown below according to the fibre type predominantly used by the selected performer.
_________________________________
Type 1 Type 2a Type 2b
Now look at Fig 2.09 to check your continuum

10. Muscle Fibres
Answer and explain the following statement: “can muscle fibre distribution predict success in certain sporting activities?”
Generally true but there are other determining factors:
- length of lever
- VO2 max
- physique
- motivation
- confidence

11. Muscle Fibres In pairs attempt the exam question
Peer mark the answer in a different colour
Make your corrections using green pen

12. The motor unit is the basic functional unit of skeletal muscle.
The motor unit is the motor nerve (neurone) and the group of muscle fibres that it controls.

13. Motor unit
Stimulation of one motor neuron causes all the muscle fibres in that motor unit to contract simultaneously.
Each muscle is made up of a number of units. The number recruited varies depending on strength required.

14. Motor unit
Number of fibres within a motor unit is dependent on control required.
Small muscle for fine motor skill may only require one fibre per motor unit e.g. eye to focus
Large muscle for gross skill may need 500 or more fibres e.g. kicking a football

15. Motor unit Motor units are usually made up of the same muscle fibre.
So we see both fast and slow twitch motor units in a muscle.

16. Plenary Activity: Look again at Who am I?, using a green pen what can
I am/can
I am Type ?
Known as slow twitch fibres I
manufacture and split ATP at a fast rate so produce fast strong contractions.
IIa
White in colour due to low level of myoglobin and few mitochondria
IIb
Red in colour due to presence of high volumes of myoglobin
Known as fast glycolytic fibres
Produce ATP at a slow rate by anaerobic metabolism
more prone to fatigue than type I fibres.
very resistant to fatigue
Known as fast oxidative fibres
contain a medium amount of myoglobin and mitochondria
break down ATP very quickly resulting in short, fast bursts of power and rapid fatigue
be turned into type IIa by resistance training
are capable of producing repeated low level contractions by producing large amounts of ATP
Look again at Who am I?,
using a green pen what can
you add to it now.
Learning Outcomes
All able to remember and understand the 3 different types of fibres
Most are able to apply knowledge of the fibres to sporting events.
Some are able to justify the proportions of muscle fibres in each muscle