BTEC NC Sport & Exercise Sciences Unit 7 Anatomy for Sport & Exercise

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The Muscular System Muscle Tissue You've got around 650 muscles in your body, and they make up roughly half of your bodyweight. These muscles can be divided into three different groups: Muscles provide the forces which move our skeleton. But they have other functions too… Muscle Tissue Involuntary Voluntary Skeletal Cardiac Smooth

Skeletal (striated) Muscle Properties:- Extensibility – ability to lengthen Highly Elastic – return to normal length after stretch Contractability - forcibly shortens on nervous/hormonal stimulation

Function of Skeletal Muscle Movement Posture & Support Heat Production

Basic Muscles of the Human Body Anterior

Basic Muscles of the Human Body Posterior

Muscle Structure

Muscle Structure Muscles are attached to bones with tendons. Tendons are made from collagen fibres. There is an Origin & Insertion for each muscle. The Origin is usually proximal. Insertion is distal. Outer layer is EPIMYSIUM The muscle itself is made up of many FASSICLES. Each Fassicle contains many muscle FIBRES (or cells). Fassicles are covered in and separated by PERIMYSIUM Perimysium is made from collagen fibres. Each Fibre is held together by ENDOMYSIUM.

Muscle Cell Structure Each Fibre consists of many MYOFIBRILS. These are the contractile units of the muscle. Each Myofibril contains many repeated units called SARCOMERES. Sarcomeres contain ACTIN & MYOSIN filaments Actin is the thin filament Myosin is the thick filament Troponin and Tropomyosin prevent muscle action. They bind to Myosin preventing Cross-Bridging. Calcium Ions (Ca+) released from Sarcoplasmic Reticulum activate the release of Troponin from Myosin. Myosin heads bind to Actin creating a ‘pulling’ action. ATP contained in the Sarcoplasm provides energy for release of binding.

Sliding Filament Theory

Types of Skeletal Muscle Fibre 3 Types exist: Type 1 – Slow Oxidative fibres (Slow-twitch fibres) Type 2(a) – Fast Oxidative Glycolytic fibres (Fast Twitch fibres) Type 2(b) – Fast Glycolytic fibres (Fast Twitch fibres)

Type 1 – Slow Oxidative fibres (Slow-twitch fibres) Red - Rich blood supply, more myoglobin Slow contraction – due to thin myelin sheath/slow nerve impulse. Aerobic - Posture & endurance events – Journeying, Hill walking.

Type 2(a)– Fast Oxidative Glycolytic fibres (Fast-twitch fibres) Much Paler – Less myoglobin Faster contraction – due to thicker myelin sheath. More fibres in each motor-unit Mainly Anaerobic – but also Aerobic Capacity Sprints/400m, Short ‘difficult’ climb, Kayak Sprint

Type 2(b) – Fast Glycolytic fibres (Fast-twitch fibres) White Fast contraction – due to thick myelin sheath. Motor Neurone Thicker – large impulse. Almost entirely Anaerobic Short Sprints, Powerful climbing moves, strong bursts of power strokes, intense uphill MTB

Fatigue Extremely Quickly! Fibre Type Properties Quality Type 1 Type 2a Type 2b Contraction Speed Slow (80 – 100 ms) Fast (40-60 ms) Very Fast (< 40ms) Force Production Low High Very High Capillary Density Medium Oxidative Capacity Exercise Capacity Fatigue Quickly Fatigue Extremely Quickly!

Sports Specific Predominance

Dependent on sufficient impulse. Innervation of fibres ‘All or Nothing’ Law Dependent on sufficient impulse.

Muscle Twitch Muscle Innervation