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

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

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.

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)

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 10-180 300-800 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.

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

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!

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

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

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

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

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.

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.

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

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.

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