Muscular system recap.

Classifications of muscles There are three types of muscle you need to know. There are three types of muscle you need to know. Cardiac muscle Cardiac muscle Skeletal muscle Skeletal muscle Smooth muscle Smooth muscle

Cardiac muscle Found only in the heart. Found only in the heart. Not under our control Not under our control The muscle cells look like one big line The muscle cells look like one big line

Smooth muscle The muscle cells are spindle shaped. The muscle cells are spindle shaped. Located around the major organs. Located around the major organs. Muscle is not under our control. Muscle is not under our control.

Skeletal muscle Muscle is attached to the bone via tendons. Muscle is attached to the bone via tendons. The muscle cell is spindle formed and consists of fibres the overlap. The muscle cell is spindle formed and consists of fibres the overlap. When electricity is induced to the muscle fibres they become shorter. When electricity is induced to the muscle fibres they become shorter. The muscles cells are voluntary, (under our control). The muscles cells are voluntary, (under our control).

Using muscles Muscle fatigue Muscle fatigue When your using your muscles a lot and they don’t get enough oxygen, they become tired or FATIGUED. When your using your muscles a lot and they don’t get enough oxygen, they become tired or FATIGUED. Muscle atrophy Muscle atrophy If you don’t use your muscles enough they become smaller and wasted, this is called MUSCLE ATROPHY. If you don’t use your muscles enough they become smaller and wasted, this is called MUSCLE ATROPHY. Cramp Cramp A sudden contraction of a muscles that wont relax, caused by a lack of blood supply to the muscle. A sudden contraction of a muscles that wont relax, caused by a lack of blood supply to the muscle.

The sliding filament theory The sliding filament theory is very complex, but can be simplified by thinking of the muscles like a giant comb, the teeth of the come are the muscle fibres and when the muscle contracts these fibres overlap pulling the tendons together making the muscle shorter. The sliding filament theory is very complex, but can be simplified by thinking of the muscles like a giant comb, the teeth of the come are the muscle fibres and when the muscle contracts these fibres overlap pulling the tendons together making the muscle shorter.

Antagonistic - agonist Muscles can only pull, because of this they must work in pairs. Muscles can only pull, because of this they must work in pairs. When one muscle contracts to move the skeletal system this is called agonist. When one muscle contracts to move the skeletal system this is called agonist. The muscle that relaxes is called the antagonist. The muscle that relaxes is called the antagonist.

The purpose of tendons Tendons are formed at the end of the muscles and attach the muscle to the bone allowing the body to move. Tendons are formed at the end of the muscles and attach the muscle to the bone allowing the body to move.

The purpose of ligaments Ligaments are designed to support joints by attaching to both bones making the joint secure during twisting and stretching movements during sport. Ligaments are designed to support joints by attaching to both bones making the joint secure during twisting and stretching movements during sport.

Types of muscle contraction Isometric contraction Isometric contraction Muscle stays the length, its like trying to move an immoveable object. Muscle stays the length, its like trying to move an immoveable object. Isotonic contraction Isotonic contraction When the muscles move and (become shorter and longer) just like weight lifting. When the muscles move and (become shorter and longer) just like weight lifting.

Muscle Fibre Types Muscle Fibre Types

Learning Outcomes By the end of this session you should be able to: 1. Identify 3 different types of fibres 2. Describe the characteristics of each type 3. Identify which sports use each type

Muscle Fibre Types Muscles are composed of thousands and thousands of individual muscle fibres Muscles are composed of thousands and thousands of individual muscle fibres Not all fibres are alike in structure and function Not all fibres are alike in structure and function Can be classified into 3 types: Can be classified into 3 types: Type IType I Type IIAType IIA Type IIBType IIB

Type I Fibres Slow twitch or slow oxidative fibres: Slow twitch or slow oxidative fibres: Red in colour Red in colour Large amounts of mitochondria, myoglobin and capillary network Large amounts of mitochondria, myoglobin and capillary network Work slowly (split ATP at a slow rate) Work slowly (split ATP at a slow rate) Able to repeatedly contract or maintain contraction for a long duration Able to repeatedly contract or maintain contraction for a long duration High resistance to fatigue High resistance to fatigue Fibres work mainly aerobically Fibres work mainly aerobically

Type IIA Fibres Fast twitch or fast oxidative glycolytic fibres (FOG) Fast twitch or fast oxidative glycolytic fibres (FOG) Similar to Type I Fibres Similar to Type I Fibres Red in colour Red in colour Large amounts of myoglobin, many mitochondria and capillaries Large amounts of myoglobin, many mitochondria and capillaries Resistant to fatigue Resistant to fatigue Work rapidly to split ATP, fast contraction speed Work rapidly to split ATP, fast contraction speed Work aerobically or anaerobically Work aerobically or anaerobically Used in high intensity, short duration activities such as 200m swim or 800m Used in high intensity, short duration activities such as 200m swim or 800m

Type IIB Fibres Fast twitch or fast twitch glycolytic (FTG) fibres Fast twitch or fast twitch glycolytic (FTG) fibres White in colour White in colour Low number of myoglobin, few mitochondria, few capillaries Low number of myoglobin, few mitochondria, few capillaries Fatigue easily Fatigue easily Fast contraction speed, split ATP quickly Fast contraction speed, split ATP quickly Much stronger force of muscle contraction Much stronger force of muscle contraction These are used for activities of a very high intensity (anaerobic) These are used for activities of a very high intensity (anaerobic) e.g. powerlifting or 100m sprinte.g. powerlifting or 100m sprint

Fibre Mix Most skeletal muscle is a mixture of all 3 types Most skeletal muscle is a mixture of all 3 types Proportion of types varies in relation to usual action of the muscle Proportion of types varies in relation to usual action of the muscle For example – the postural muscles of the neck and back and leg have a higher proportion of Type I Fibres For example – the postural muscles of the neck and back and leg have a higher proportion of Type I Fibres Why do you think this is? Why do you think this is?

Fibre type and athletic success l Some outstanding athletes have a much higher percentage of whatever fibre type is most advantageous to their event l Elite distance runners - calf muscles composed of 90% slow twitch (Type I) fibres

Fibre type and athletic success l Sprinters - 92% fast twitch (Type II) fibres l What role does genetics play in determining this? l The slow and fast twitch characteristics of muscle fibres appear to be determined early in life, perhaps within the first few years

Fibre type and athletic success l Studies have revealed that identical twins have nearly identical fibre compositions l Little evidence showing change of fibre type from a few weeks training l More recent evidence suggests the possibility of fibre type change with high volume of training l However, the percentage of change is too small to make a difference in sports that require a high percentage of one fibre type to another

Effects of Exercise on Fibre Type Can change the characteristics of some fibre types Can change the characteristics of some fibre types Some Type IIB fibres can transform into Type IIA fibres with long distance endurance training Some Type IIB fibres can transform into Type IIA fibres with long distance endurance training Prolonged endurance training has been shown to increase the diameter of Type IIB fibres, increase the no. of mitochondria within the fibres, and increase the capillaries surrounding the fibres Prolonged endurance training has been shown to increase the diameter of Type IIB fibres, increase the no. of mitochondria within the fibres, and increase the capillaries surrounding the fibres The fibres can then use the aerobic energy system more efficiently The fibres can then use the aerobic energy system more efficiently

Effects of Exercise (cont) Strength training can increase the size of Type IIB fibres (greater muscle mass - hypertrophy) Strength training can increase the size of Type IIB fibres (greater muscle mass - hypertrophy) No increase in the number of fibres No increase in the number of fibres