Certificate III in Fitness

Introduction to Anatomy and Physiology (IAP)

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Certificate III in Fitness

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Contents Chapter 1 – SISFFIT004 – Incorporate anatomy & physiology principles into fitness programming .. 3

Anatomical terminology ..................................................................................................................... 3

Movement terminology and muscle actions ...................................................................................... 6

Structural levels of body organisation .............................................................................................. 14

Functions of major muscles during exercise and movement ........................................................... 16

Types of muscle contractions ........................................................................................................... 17

Tissue types ....................................................................................................................................... 18

Body systems, their interdependence and contribution to a healthy body ..................................... 22

Structure and function ...................................................................................................................... 23

Respiratory System ........................................................................................................................... 48

Energy systems, pathways and substrates and relevant recovery options ...................................... 51

Thermoregulation of the human body ............................................................................................. 55

Posture .............................................................................................................................................. 57


Chapter 1 – SISFFIT004 – Incorporate anatomy & physiology principles into fitness programming

Anatomical terminology Anatomic terms describe the directions within the body as well as the body’s reference planes. Many of these are taken from Latin and Greek languages, and each has a very specific meaning. The terms used to describe locations and positions reference a person in the standard anatomical position.

The Anatomical Position Anatomy is the study of the structure of the human body, and the anatomical position is the central concept behind all descriptions of location within the body. The anatomical position (neutral position) is the starting position for describing any movement. It is important that you know this to be able to understand what is meant by certain movement patterns

• Standing tall

• Legs together and knees straight

• Arms by the sides

• Palms facing forward

• Toes pointing forward

Directional Terms Various body parts and their relationship with other similar body parts can be easily understood by the usage of Directional terms in anatomy. Directional terms simply describe the position of one part of the body in relation to another. Most of the directional terms used to describe the relationship of one part of the body to another can be grouped into pairs that have opposite meanings. For example, superior means toward the upper part of the body, and inferior means toward the lower part of the body. It is important to understand that directional terms have relative meanings; they


make sense only when used to describe the position of one structure relative to another. For example, your knee is superior to your ankle, even though both are in the inferior half of the body. Understanding directional terms is important because it helps you communicate with other fitness professionals and clients, as well as complete everyday aspects of your job such as instructing correct exercise technique, assessing someone’s movement and creating a balanced exercise program.

• Anterior (or ventral): Towards the front of the body o The mouth is on the anterior part of the head

• Posterior (or dorsal): Towards the back of the body o The spine is on the posterior part of the trunk

• Medial: Towards the midline/inside of the body o The big toe is medial to the little toe

• Lateral: away from the midline of the body o The ears are on the lateral part of the head

• Superior: Above another body part o The head is superior to the stomach

• Inferior: Below another body part o The liver is inferior to the diaphragm

• Proximal: When a body part is closer to the trunk than another o The thighs are proximal to the toes

• Distal: When a body part is further from the trunk than another o The fingernails are at the distal ends of the fingers

• Superficial: Superficial means toward, nearer to, or on the surface of the body o The skin is superficial to bones

• Deep: Means away from the surface of the body o Bones are deep to the skin

• Ipsilateral: Means a part of the body is on one side in relation to another o The right Radius and right Humerus are ipsilateral

• Contralateral: This means that organs or body parts being discussed are on the opposite sides

o The eyes are contralateral to each other


The Planes of Movement Movements (directional movements) of the human body are also often described in terms of the ‘plane’ in which they pass through. The planes are imaginary lines (vertical or horizontal) drawn through an upright body. There are three planes of motion in which we move:

Sagittal Plane The sagittal plane divides the body into left and right. When we move along this plane, we are using the strength of our muscles to move parts of the body forward or backward. This means most running, biking, rowing, and lifting movements make use of this plane. For example, in a squat, both hips move from extension into flexion, and back into extension. The hips and knees spend a lot of time in flexion, so mobility work should involve extending both joints.

Frontal Plane The frontal plane (coronal plane) divides the body into anterior (front) and posterior (back) parts. When we move along this plane, we are moving toward or away from the midline. Many of our daily movements and exercises involve very little abduction. We tend to stay neatly hugged in toward the middle.

Transverse (horizontal) Plane The transverse plane divides the body into superior(top) and inferior(bottom) parts, but it is a little less straightforward. Any time we rotate a joint, we are moving along the transverse plane. In daily life, this is the action that is performed least frequently, particularly with the large joints in the hips, shoulders, and spine.


Most movements are not straight up and down, or side to side, i.e. one dimensional. If they were, you wouldn’t be able to move your leg away from you, toward you, in front or behind you. Your body moves in three dimensions and therefore combines a mixture of movements in different planes. Here’s a rundown of the different types of movement that occur within each plane: Sagittal

• Flexion

• Extension

• Dorsiflexion

• Plantarflexion Frontal

• Adduction

• Abduction

• Elevation

• Depression

• Inversion

• Eversion Transverse

• Rotation - Internal and External

• Pronation

• Supination

• Horizontal Flexion

• Horizontal Extension

Movement terminology and muscle actions The language of movement is designed to allow us to describe how the body moves through space The anatomical position is the frame of reference for the language of movement. Knowing how the body moves and the actions that various joints allow is crucial for safe and effective exercise instruction. Selecting exercises to work muscle groups or simulate sports movements. Knowing the language of movement will also allow you to communicate with other exercise professionals in a common language.


• Flexion: Where the angle between two bones decreases o Think bending

• Extension: Where the angle between two bones increases o Think straightening

o Note: Hyperextension is an extension of a joint beyond anatomical position. It is not considered to be aa anatomical movement as such.

• Horizontal flexion: Where the angle between two bones decreases in the transverse (horizontal) plane


• Horizontal extension: Where the angle between two bones increases in the transverse (horizontal) plane

• Abduction: Movement of a limb away from the midline of the body

• Adduction: Movement of a limb toward the midline of the body


• Pronation (hand): Movement of the forearm so the palm faces downward or backward

• Supination (hand): Movement of the forearm so the palm faces up or forward

• Elevation: Moving a body part superiorly o Think shrugging the shoulders o The scapula moves to a more superior position


• Depression: Moving a body part inferiorly o Think carrying 2 heavy suitcases o The scapula moves to a more inferior position as they are pulled downwards

• Inversion: Is when the plantar surface (bottom) of the foot turns medially

• Eversion: Is the when the plantar surface of the foot turns laterally


• Dorsi-flexion: Is moving the top of the foot toward the shin or ‘raising’ the toes

• Plantar-flexion: Is moving the top of the foot away from the shin or ‘pointing’ the toes

• Lateral trunk flexion: Refers to movement of the spine laterally away from the midline of the body

o When you bend to one side


• Circumduction: This is a movement where the joint is the pivot, and the body segment moves in a combination of flexion, extension, adduction and abduction

• Protraction: This is forward movement of the scapula that results in ‘hunching’ of the shoulders

• Retraction: This is backward movement of the scapula as they pull together to ‘square’ the shoulders and push the chest out


• Rotation: Refers to a pivoting or ‘twisting’ movement o Rotation is broken down further into medial and lateral rotation

• Medial (internal) rotation: The movement of a body segment where the front (anterior) of the segment rotates medially (inwards) towards the midline of the body

• Lateral (external) rotation: The movement of a body segment where the front (anterior) of the segment rotates laterally (outwards) away from the midline of the body


Structural levels of body organisation The human body has many levels of structural organisation:

• Atoms

• Cells

• Tissues

• Organs

• Organ system The simplest level is the chemical level. The chemical level includes the tiniest building blocks of matter, atoms, which combine to form molecules, like water, carbohydrates, proteins, fats, etc. In turn, molecules combine to form organelles, the internal organs of a cell. Cells are the smallest functional units of life. Individual cells may have some common functions but vary widely in size and shape. The average number of cells in the human body is 100 trillion. Each type of cell carries out a set of unique tasks within the human body, e.g. the conversion of nutrients into energy, reproduction (cell division) etc. Tissues are groups of similar cells that perform specialised functions. The four basic tissue types are epithelial, muscle, connective, and nervous tissue. Each tissue type has a characteristic role in the body:

• Epithelium covers the body surface and lines body cavities

• Muscle provides movement

• Connective tissue supports and protects body organs

• Nervous tissue provides a means of rapid internal communication by transmitting electrical impulses

An organ is a structure that is composed of at least two or more tissue types and performs a specific set of functions for the body. The liver, stomach, brain, and blood are all organs. Organs can be classified based on the functions they perform. For example, the tongue, ears, eyes, skin, and nose are sensory organs. Many organs working together to accomplish a common purpose create an organ system. For example, the heart and the blood vessels of the cardiovascular system circulate blood and transport oxygen and nutrients to all the body cells. Besides the cardiovascular system, the other organ systems of the body are the integumentary, skeletal, nervous, muscular, endocrine, respiratory, lymphatic, digestive, urinary, and reproductive systems An organism is the highest level of organisation. It is the total of all structural levels working together. In short, it is the human being (or organism) as a whole.



Functions of major muscles during exercise and movement Muscles must work together to produce different bodily movements, and a muscle’s role may change depending on the movement. While many muscles may be involved in any given action, muscle function terminology allows you to quickly understand the various roles different muscles play in each movement. There are four different roles that a muscle can fulfil during movement, these roles are;

• Agonist

• Antagonist

• Synergist

• Fixator

Agonist The agonist(s) in a movement are all the muscle(s) that provide a force to help complete the movement. This can sometimes be a single muscle, but sometimes there can be multiple muscles involved in the movement. The muscle which initiates the movement, and provides the major force behind the movement, is known as a “Prime mover”. For example, in the bicep curl, which produces flexion at the elbow joint, the Brachialis, Brachioradialis and Biceps Brachii are all agonists. In this instance, though, the Brachialis is the “Prime mover” as it is the agonist that initiates the movement and does most of the work. The expectation at a Cert III level is to be aware of muscle groups, not specifically each muscle within the group itself. It is important to remember that the agonist is not always the muscle that is shortening (contracting concentrically). For example, in a bicep curl, the bicep is the agonist on the way up when it contracts concentrically, and on the way down when it contracts eccentrically. It is the prime mover in both cases.

Antagonist An antagonist muscle is in opposition to a prime mover in that it provides some resistance and/or reverses a given movement. For example, during elbow flexion where the bicep is the agonist, the tricep muscle is the antagonist. While the agonist contracts causing the movement to occur, the antagonist typically relaxes so as not to impede the agonist. The antagonist doesn’t always relax though, another function of antagonist muscles can be to slow down or stop a movement. For example, you would see this if the weight involved in the bicep curl was very heavy. When the weight was being lowered from the top position, the antagonist tricep muscle would produce enough tension to help control the movement as the weight lowers. This helps to ensure that gravity doesn’t accelerate the movement causing damage to the elbow joint at the bottom of the movement. Prime movers and antagonists are often paired up on opposite sides of a joint, with their prime mover/antagonist roles reversing as the movement changes direction. For example, the triceps become the agonist and the bicep the antagonist when the elbow extends against gravity such as in a push-up, a bench press or a tricep pushdown.

Synergist The synergist in a movement is the muscle(s) that stabilises a joint around which movement is occurring, which in turn helps the agonist function effectively. Synergist muscles also help to create


the movement. For example, in the bicep curl, the synergist muscles are the brachioradialis and brachialis which assist the biceps to create the movement and stabilise the elbow joint.

Fixator The fixator in a movement is the muscle(s) that stabilises the origin of the agonist and the joint that the origin spans (moves over) to help the agonist function most effectively. For example, in the bicep curl, this would be the rotator cuff muscles, the ‘guardians of the shoulder joint.’ Fixator muscles are most commonly found in the two major joints on the body, the hip and the shoulder joints. Fixators are also sometimes called stabilisers.

Types of muscle contractions The contraction of a muscle does not necessarily imply that the muscle shortens; it only means that tension has been generated. Muscles can contract in the following ways

• Isotonic – concentric and eccentric

• Isokinetic

• Isometric

Isotonic contractions Isotonic contractions are those which cause the muscle to change length as it contracts and causes movement of a body part. There are two types of isotonic contractions:

• Concentric

• Eccentric Ask someone to flex, and they are likely to perform a concentric contraction. Next time you walk through your local gym, I am sure you will see the emphasis of people’s workout will be on concentric work only. With a concentric contraction, a muscle shortens its fibres to cause a joint movement to occur. For example, when you sit in a chair and flex your elbow joint to 90 degrees, the biceps in the anterior aspect of your arm contract concentrically to produce this movement. If you continue to hold your arm in this position, biceps are working isometrically to maintain the position against the pull of gravity. With an eccentric contraction, a muscle lengthens its fibres to cause a joint movement to occur. For example, in the squat exercise, the quadricep muscles will contract eccentrically (lengthen) in the downward phase of the movement. Concentric and eccentric are also terms used to describe the phase of a movement. The concentric phase is the phase of the movement that is overcoming gravity or load, while the eccentric phase is the phase resisting gravity or load. For example, in a push-up, the concentric phase is the up phase where gravity is overcome, and the eccentric phase is the downward phase where gravity is resisted.

Isometric With isometric contractions, muscles don’t need to move (shorten or lengthen) at all to contract or develop tension. An isometric contraction refers to any contraction of muscles where little or no movement occurs. For example, if during the squat a person stopped moving at a certain point (say halfway up) and held that position for 5 seconds, the quadriceps muscle would be contracting isometrically, it would still be under load/tension, but no movement would occur.


Isokinetic Isokinetic contractions are like isotonic contractions, in that the muscle changes length during the contraction. Where they differ is that isokinetic contractions produce movements of a constant speed. Examples of using isokinetic contractions in the day-to-day and sporting activities are rare; they are mainly performed under artificial conditions, such as when using a machine called an isokinetic dynamometer.

Tissue types The term tissue is used to describe a group of cells found together in the body. Although there are many types of cells in the human body, they are organised into four broad categories of tissues: epithelial, connective, muscle, and nervous. Each of these categories is characterised by specific functions that contribute to the overall health and maintenance of the body.

Epithelial tissue Epithelial tissues(epithelium) are widespread throughout the body. They form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception. For example, the skin is an organ made up of epithelial tissue which protects the body from dirt, dust, bacteria and other microbes that may be harmful. Cells of the epithelial tissue have different shapes. Cells can be thin, flat(squamous) to cubic(cuboidal) to elongated(columnar) may be arranged in single or multiple layers.


Connective tissue Connective tissues bind structures together, form a framework and support for organs and the body, stores fat, transport substances, protect against disease, and help repair tissue damage. Connective tissue is the most abundant and the most widely distributed of the tissues. All connective tissue consists of three main components: fibres (elastic and collagenous fibres), ground substance and cells. Connective tissue cells can reproduce but not as rapidly as epithelial cells. Most connective tissues have a good blood supply, but some do not. The following tissues are found in the human body, ordinary loose connective tissue, adipose (fat) tissue, dense fibrous tissue, cartilage, osseous tissue (bone), blood, and lymph, which are all considered connective tissue


Muscle tissue Muscle tissue plays the vital role of providing movement and heat generation to the organs of the body. Within muscle tissue are three distinct groups of tissues: skeletal muscle, cardiac muscle, and smooth muscle. Each of these tissue groups is made of specialised cells that give the tissue its unique properties. Skeletal Muscle Skeletal muscle is the most common and widely distributed muscle tissue in the body, making up around 40% of the body’s total mass. It forms all the skeletal muscles, such as the biceps brachii and gluteus maximus, and is found in the eyes, throat and diaphragm. Four characteristics define skeletal muscle tissue cells: they are voluntary, striated, not branched, and multinucleated. Skeletal muscle tissue is the only muscle tissue under the direct conscious control of the cerebral cortex of the brain, giving it the designation of being voluntary muscle. All conscious movements of the body, including movement of the limbs, facial expressions, eye movements, and swallowing are the products of skeletal muscle tissue. The contraction of skeletal muscles also produces the bulk of the body’s heat as a by-product of cellular metabolism. When viewed under the microscope, skeletal muscle cells appear to have a striped, or striated, pattern of light and dark regions. These stripes are caused by the regular arrangement of actin and myosin proteins within the cells into structures known as myofibrils. Myofibrils are responsible for the skeletal muscles’ great strength and ability to pull with incredible force and propel the body. Cardiac Muscle Cardiac muscle cells are found only in the heart and are specialised to pump blood powerfully and efficiently throughout a person’s lifetime. Four characteristics define cardiac muscle tissue cells: they are involuntary and intrinsically controlled, striated, branched, and single nucleated. Cardiac muscle is an involuntary tissue because it is controlled unconsciously by regions of the brain stem and hypothalamus. It is also considered to be an intrinsic, or self-controlled, tissue because the normal cardiac rhythm is set by specialised pacemaker cardiac muscle cells in the heart itself. The cells of cardiac muscle tissue are shorter than skeletal muscle tissue and form a network of many branches between the cells. Intercalated disks of overlapping cell membrane form between the cardiac muscle cells to lock them together tightly, and allow the quick passage of electrochemical signals between cells. The cells do not fuse during development, leaving each cell with a single nucleus. One commonality between skeletal and cardiac muscle is the presence of striations due to the arrangement of actin and myosin into regular myofibrils. The presence of myofibrils and many mitochondria in cardiac muscle cells provides them with great strength and endurance to pump blood throughout an entire lifetime. Visceral Muscle Visceral muscle cells are found in the organs, blood vessels, and bronchioles of the body to move substances throughout the body. Visceral muscles are also commonly known as smooth muscle due to their lack of striations. Four characteristics define smooth muscle tissue cells: they are involuntarily controlled, not striated, not branched, and singly nucleated. The unconscious regions of the brain control visceral muscle through the autonomic nervous system. Thus, visceral muscle is involuntarily controlled. This is evidenced by the inability to consciously control many physiological processes such as blood pressure or digestion. Each visceral muscle cell is long and thin, with a single central nucleus and many protein fibres.


Nervous tissue Nervous tissue is found in the brain, spinal cord, and nerves. It is responsible for coordinating and controlling many body activities. It stimulates muscle contraction, creates an awareness of the environment, and plays a major role in emotions, memory, and reasoning. Nervous tissue is grouped into two main categories: neurons and neuroglia. Neurons, or nerves, generate and transmit signals called nerve impulses, or action potentials, while neuroglia do not. Neurons have three principal parts: the dendrites, the cell body, and one axon. The main part of the cell, the part that carries on the general functions, is the cell body. Dendrites are extensions, or processes, of the cytoplasm that carry impulses to the cell body. An extension or process called an axon carries impulses away from the cell body. Neuroglia or glial cells do not transmit impulses, but instead, support the activities of the neurons, supply them with nutrients, get rid of dead cells and pathogens such as bacteria. They also bind neurons together and form insulation between neurons so that electrical signals do not get crossed.


Body systems, their interdependence and contribution to a healthy body The human body contains trillions of cells, 78 different organs and more than 1000,000 kilometres of blood vessels. These cells, vessels and organs work together to keep us alive. Each cell, vessel and organ belong to one of 11 body systems.

• The skeletal system makes up the framework of the body and allows us to move when our muscles contract. It stores minerals (e.g. calcium, phosphorous) and releases them into the body when they are needed. The skeletal system also protects internal organs and produces blood cells

• The cardiovascular (circulatory) system delivers oxygen and nutrients to the tissues and carries waste products to the organs responsible for elimination

• Different types of muscles enable motion, generate heat to maintain body temperature, move food through the digestive tract and contract the heart

• The nervous system is responsible for the control of the body and communication among its parts

• The endocrine system secretes hormones into blood and other body fluids. These chemicals are important for metabolism, growth, water and mineral balance, and the response to stress

• The lymphatic system helps rid the body of toxins, waste and other unwanted materials

• The respiratory system supplies oxygen to the blood and removes carbon dioxide

• The digestive system stores and digests foods; transfers nutrients to the body, eliminates waste and absorbs water

• The reproductive system is responsible for producing new life

• The urinary system produces, stores and eliminates urine, the fluid waste excreted by the kidneys

• The urinary system removes waste products such as urea, uric acid, and creatinine from the blood to be passed out of the body as urine

• The integumentary system reduces water loss, contains receptors that respond to touch, regulates body temperature, and protects the inside of the body from damage


Each individual body system works in conjunction with other body systems. The cardiovascular system is a good example of how body systems interact with each other. Your heart pumps blood through a complex network of blood vessels. When your blood circulates through your digestive system, for example, it picks up nutrients your body absorbed from your last meal. Your blood also carries oxygen inhaled by the lungs. Your cardiovascular system delivers oxygen and nutrients to the other cells of your body then picks up any waste products created by these cells, including carbon dioxide, and delivers these waste products to the kidneys and lungs for disposal. Meanwhile, the cardiovascular system carries hormones from the endocrine system and the immune system’s white blood cells (Leukocytes) that fight off infection. Each of your body systems relies on the others to work well. Your respiratory system relies on your circulatory system to deliver the oxygen it gathers. At the same time, the muscles of your heart cannot function without the oxygen they receive from your lungs. The bones of your skull and spine protect your brain and spinal cord, but your brain regulates the position of your bones by controlling your muscles. The cardiovascular system provides your brain with a constant supply of oxygen-rich blood while your brain regulates your heart rate and blood pressure. Even seemingly unrelated body systems are connected. Your skeletal system relies on your urinary system to remove waste produced by bone cells; in return, the bones of your skeleton create a structure that protects your bladder and other urinary system organs. Your cardiovascular system delivers oxygen-rich blood to your bones. Meanwhile, your bones are busy making new blood cells. Working together, these systems maintain internal stability and balance, otherwise known as homeostasis.

Structure and function

Muscular System The muscular system is made up of the muscles of the body and the tendons (tough, dense fibrous bands that join muscle to bone) that connect them to the skeleton. Muscles are one of those things that most of us take entirely for granted, but they are incredibly important for two key reasons;

• Muscles are the "engine" that your body uses to propel itself

• It would be impossible for you to do anything without your muscles Muscles are made of many cells called fibres (think of muscle fibres as long cylinders). Length of these cylinders varies from a few millimetres to many centimetres. Each fibre is made up of long thin cells which are packed in bundles. Each bundle is wrapped in a thin skin (tissue) called perimysium (perry-miss-ee-um). Each muscle has lots of these bundles. The bigger the muscle, the more bundles of fibres it has.


Groups of muscle bundles that join into a tendon at each end are called muscle groups, or simply muscles. When most people think of "muscles," they think about the muscles that we can see, for example, most of us know about the biceps muscles in our arms. But there are three different types of muscle within our bodies, these are;

• Skeletal muscle

• Cardiac muscle

• Smooth muscle Each type of muscle also has its own unique role that it performs within our bodies. Skeletal muscle

• Skeletal muscles connect to tendons and bones and are responsible for creating movement

• Skeletal muscles are under voluntary control

• Voluntary muscles are the ones that you can control

• The brain sends messages to the muscle to 'contract' or 'relax' Cardiac muscle

• Cardiac muscle is found only in your heart and pumps blood around your body

• Cardiac muscle can contract with the force of a skeletal muscle

• Cardiac muscle contracts involuntarily

• Involuntary muscles don't need the brain to send them messages. They know their job and keep performing it

Smooth muscle

• Smooth muscle forms the walls of internal organs that are hollow, like your digestive system, blood vessels, bladder, airways and, in a female, the uterus

• Smooth muscle is responsible for expanding and contracting allowing blood and fluids to enter and pass through the vessels and organs at varying rates

• Smooth muscle contraction occurs involuntarily and more slowly than skeletal muscle contraction. For example, your stomach and intestines do their muscular thing all day long, and, for the most part, you never know what's going on in there

Important - Both cardiac and smooth muscles are fatigue-resistant (they don’t tire), as opposed to skeletal muscle which fatigues relatively easily. Shapes of skeletal muscle As you already know, skeletal muscle comes in many different sizes and are made up of bundles of fibres. How these bundles of fibres are arranged varies considerably, resulting in muscles with different shapes that allow them to do many types of jobs Muscles come in five different shapes;

• Circular

• Convergent

• Parallel

• Pennate

• Fusiform


Circular In shape, these muscles appear circular and normally surround external body openings, which they close by contracting. The general term used for these kinds of muscles is “sphincter”. The orbicularis oris is an example of a circular muscle. Convergent These are muscles where the base is much wider than the insertion, giving the muscle a triangular or fan shape. This fibre arrangement allows the muscle to contract with great force. The pectoralis major is an example of a convergent muscle.

Parallel Parallel muscles have fibres which run parallel to each other and are sometimes called strap muscles. They are generally long muscles which cause large movements, are not very strong but have good endurance. The sartorius is an example of a parallel muscle.

Pennate Pennate muscles have many muscle fibres that attach obliquely (in a slanting position) to its tendon and are very strong but tire easily. Pennate muscles come in three forms;

• Unipennate: All the muscle fibres are on the same side of the tendon o An example is the extensor digitorum longus

• Bipennate: The muscle fibres on both sides of the central tendon Like a feather o An example is the rectus femoris

• Multipennate: There are multiple rows of diagonal fibres, with a central tendon which branches into two or more tendons

o An example is the deltoid muscle which has three sections; anterior, posterior and middle

Fusiform Sometimes included in the parallel muscle group, these muscles are more spindle-shaped, with the muscle belly being wider than the origin and insertion. The biceps brachii is an example of a fusiform muscle.


Muscle fibre types Within skeletal muscle there are three types of fibre;

• Type I - slow twitch (I)

• Type II A - fast twitch (IIa)

• Type II B - fast twitch (IIb) Each one has its own characteristics and is suited to a movement. Type I - slow twitch (I) Type I fibres are “slow twitch” fibres. They use oxygen to fire, and they take longer to get going, but they can go for a longer period without getting tired (resistant to fatigue). For this reason, the muscles containing mainly slow twitch fibres are often postural muscles such as those in the neck and spine due to their endurance capabilities. The force per contraction on these muscle fibres is spread out over time. People who have trained for marathons and enjoy running long distances will have a higher percentage of type I fibres than a sprinter. Marathon runners, cross-country skiers and distance cyclists often possess up to 90% slow twitch fibres. Athletes that rely on short bursts of energy possess the lowest levels of slow twitch fibres, often around only 25%. Type II A - fast twitch (IIa) These fibres are fence-sitters… halfway between type I and type IIb. These are equal parts aerobic (oxygen dependant) and anaerobic (no oxygen used). They are the “jack of all trades” muscle fibre. Not great at long distances, not great at sprinting, but pretty good for either. This makes them most suitable to stop and go activities such as basketball, soccer, and hockey, as well as max output activities such as weightlifting, and many track and field events. Type II B - fast twitch (IIb) Type IIb fibres are “fast twitch” fibres. These fire anaerobically (without oxygen), they fire extremely quickly, but they get tired easily. These fibres are recruited in activities that require an all-out burst, e.g. powerlifting and 100 metre sprints. Sprinters and most fast animals in nature (cheetahs, lions,


deer, etc.) will have more “fast twitch” fibres. People who are loaded with type IIb fibres will tire more easily on long distance runs, but they will beat you off the line in a quick race. A person’s muscle fibre composition is already built into their genetics. They are born with a certain percentage of each muscle fibre, and they will affect how successful they are at either developing as say a long-distance runner, or sprinter. Most bodies have around 60% fast-twitch and 40% slow-twitch fibres; however, some individuals like elite athletes can have up to 90% of one or the other. Therefore, different people can be more suited to either short, fast or long duration activities. A sprinter with 80% fast-twitch fibres will have a better chance of being fast than somebody with only 30% fast-twitch fibres. The good news is that it’s possible through training to adjust the levels of each of the types of muscle fibres. Don’t get too excited, fibre types can’t be changed; however, fibres can adapt to the type of training they are exposed to. So, if your genetics say you should run marathons, but you really want to be a sprinter, with the right amount of training, your slow-twitch fibres would overtime begin to behave more like fast twitch muscle fibres. Global and local muscular systems The muscles which are responsible for movement and postural control can be divided into 2 systems/groups: the local muscular system (stabilisation system) and the global muscular system (movement system). The terms local and global simply refer to the location of the muscle in relation to the joint of motion. Local and global muscles are deemed more prone to stabilisation not based upon fibre type, rather on their biomechanical advantage (or disadvantage) relative to the joint. The smaller the moment arm (leverage system) of the muscle, the less torque or motion (concentric/eccentric action) it will be able to induce. Thus, by default, they may be better delegated to stabilising (isometric action). Conversely, a larger moment arm generally indicates a muscle’s greater distance from the joint and the greater potential to manipulate movement. Both the local and global muscle systems must work together for efficient normal function. Neither system in isolation can control the functional stability of body motion segments. The local muscles are predominantly involved in joint support or stabilisation. They are not typically movement producers but provide stability to allow movement of a joint. They are usually located near the joint and have a broad spectrum of attachments to the passive elements of the joint, making them ideal for increasing joint stiffness and stability, such as the transverse abdominis and multifidus. The major local muscles include the:

• Deep cervical flexors

• Rotator cuff

• Rhomboids

• Mid and lower trapezius

• Transversus abdominis

• Multifidus

• Diaphragm

• Muscles of the pelvic floor

• Gluteus medius and minimus

• External rotators of the hip

• Vastus medialis obliquus


The global muscles are predominantly larger and responsible for movement. They consist of more superficial musculature that attaches from the pelvis to the rib cage and/or the upper and lower extremities. They are associated with movement of the trunk and limbs and equalising external loads placed upon the body. They also are important for transferring and absorbing forces from the upper and lower extremities to the pelvis. The major global muscles include the:

• Sternocleidomastoid

• Upper trapezius

• Levator scapulae

• Pectoralis major

• Deltoid

• Latissimus dorsi

• Rectus abdominis

• External obliques

• Erector spinae

• Gluteus maximus

• Hamstrings

• Quadriceps

• Iliopsoas

• Adductors

• Gastrocnemius/soleus

Major muscle groups There are over 600 skeletal muscles in the human body, but very few qualify as major muscle groups. Major muscles are the largest muscle groups in the body and are largely responsible for large body movements. But although these major muscles perform the move, they are helped by many small muscles called synergists. Major muscles will mostly be the prime movers, but they cannot act alone.

The major muscle groups are:

• Trapezius, also known as traps

• Triceps

• Back o Rhomboids o Latissimus dorsi, also known as lats o Erector spinae

• Gluteals, also known as glutes

• Hamstrings

• Calves

• Shoulders, also known as deltoids

• Chest or pectoralis, also known as pecs

• Biceps

• Abdominals, also known as abs

• Quadriceps, also known as quads


Contractibility and activation Muscle tissue is very resilient and can be stretched or shortened at high speeds without significant damage to the tissue. The performance of muscle tissue under varying loads and speeds is determined by the four properties of the muscle tissue: irritability, contractility, extensibility, and elasticity. Irritability or excitability is the ability to respond to stimulation (all muscles respond to stimulus). In a muscle, the stimulation is sent through a motor neuron that releases a chemical neurotransmitter. All muscles are linked to nerve fibres that carry messages from the central nervous system Contractility (contractibility) is the ability of a muscle to generate tension and shorten when it receives enough stimulation. Contractibility enables a muscle to become shorter or thicker, and this ability, along with interaction with other muscles, produces movement of internal and external body parts Extensibility is the muscle’s ability to lengthen or stretch to their normal resting length and beyond to a limited degree. The skeletal muscle itself cannot produce the elongation; another muscle or an external force is required. With the application of force, muscle can be stretched without damage if it is not stretched past its physiological limits. Typically, smooth muscle is subjected to the greatest amounts of stretching. Elasticity is the ability of muscle fibres to return to its resting length after being stretched. Muscles require the property of elastic recoil for them to be able to do their jobs. A useful analogy is that of an elastic band, that will always resume its resting shape after it has been stretched. This property enables the muscle to prepare for a series of repeated contractions, which is typically required when performing activities in daily life, exercise or sport. All these properties are essential for all body actions, including movement and posture.


Nervous System Nerves and nerve impulses The nervous system is the highway along which your brain sends and receives information about what is happening in the body and around it. This highway is made up of billions of nerve cells, or neurons which join together to make nerves.

• A nerve is a fibre that sends impulses through the body

• These fibres are covered by a fatty substance called myelin. Myelin helps the messages go fast through the neurons

• Nerve cells work by a mixture of chemical and electrical action

The two main parts of the nervous system are the central nervous system and the peripheral nervous system. The central nervous system The brain and the spinal cord make up the central nervous system. The brain lies protected inside the skull and from there controls all the body functions by sending and receiving messages through nerves. The peripheral nervous system The peripheral nervous system carries messages to and from the central nervous system. It sends information to the brain and carries out orders from the brain. There are two major parts to the peripheral nervous system. The somatic system and the autonomic system. Somatic system

• sends sensory information to the central nervous system through peripheral nerve fibres. Sensory means that it sends the information coming from all your senses, touch, vision, hearing, taste, smell and position.

• sends messages to motor nerve fibres to get the muscles to move the body. Autonomic system

• is responsible for making sure that all the automatic things that your body needs to do to keep you going, like breathing, digesting etc. continue working smoothly without your having to think about them.

The autonomic nervous system is further subdivided into the sympathetic and the parasympathetic nervous systems. The sympathetic nervous system is activated in cases of emergencies to mobilise energy, while the parasympathetic nervous system is activated when organisms are in a relaxed state. How nerve cells work At the end of each nerve cell, there is a synaptic terminal. This is full of extremely tiny sacs which hold neurotransmitter chemicals.

• These chemicals transmit nerve impulses from one nerve to another or from nerves to muscle cells

• An electrical nerve impulse travels along the neuron to these sacs which then release the neurotransmitter chemicals


• The chemicals move along to the next neuron sparking an electrical charge which moves the nerve impulse forward

• This happens several times until the message gets where it's going

• It's a bit like you running around the house switching lights on. Pressing the switch causes electricity to flow through to the light bulb

Messages travel through the cranial nerves, which then branch out from the brain and go to many places in the head such as the ears, eyes and face. Messages can also travel through the spinal nerves, which branch out from the spinal cord. Reflex arcs and relationship to stretching The nervous system is very complex. For most major actions in the body, the brain must decide what movement or action must be taken. The nerve impulses must be transmitted out of the brain, down the spinal cord and out to the intended receiver. Then when the action is carried out, the impulse must return via the reverse pathway to tell the brain it was completed and start the next process. This is the path for any brain-controlled, conscious, impulses. Many processes in the body do not require direct thought to complete. The heart functions, breathing, metabolic processes, disease fighting, and many other autonomic processes happen automatically in the body. The body uses signals to increase, decrease, or maintain any of these actions. For example, if the carbon dioxide levels in the body begin to rise, the autonomic nervous system, through acid/base thermostats, calls for an increase in respiratory rate. Another automatic response by the nervous system is the reflex. The body reacts in a predetermined way based on specific stimulus. This may be a practised response or a pre-programmed one. A reflex arc is a nerve pathway that connects certain muscle groups to others, without involving the brain. These sorts of pathways primarily control involuntary movements in response to some sort of stimulus. Rapidly blinking the eyes in response to dust or dirt in the air is one example; coughing when food is lodged in the windpipe and kicking the leg out when whacked in the centre of the knee are others. Reflex arcs are wholly independent of the pathways that most nervous impulses travel on. The stretch reflex (or myotatic reflex) is one of those responses. What is the Stretch Reflex? The stretch reflex; which is also often called the myotatic reflex, knee-jerk reflex, or deep tendon reflex, is a pre-programmed response by the body to a stretch stimulus in the muscle. When a muscle spindle is stretched, an impulse is immediately sent to the spinal cord, and a response to contract the muscle is received. Since the impulse only has to go to the spinal cord and back, not all the way to the brain, it is a rapid impulse. It generally occurs in 1-2 milliseconds. This is designed as a protective measure for the muscles, to prevent tearing. The muscle spindle is stretched, and the impulse is also immediately received to contract the muscle, protecting it from being pulled forcefully or beyond a normal range. What causes it? The stretch reflex is caused by a stretch in the muscle spindle. When the stretch impulse is received a rapid sequence of events follows. The motor neuron is activated and the stretched muscles, and its supporting muscles, are contracted while its antagonist muscles are inhibited. The stretch reflex can be activated by external forces (such as a load placed on the muscle) or internal forces (the motor neurons being stimulated from within.) An example of the former is a person holding an empty tray in their outstretched arm and then having a plate of food set on it. The


stretch reflex would kick in to keep the tray at the same height and balanced. An example of the latter would be the shivering of a cold muscle. The motor neurons are stimulated from an internal “stretch” to warm the muscles. Any abrupt, forceful stretch on the muscle causes the stretch reflex to fire, in a healthy person. Delays in or absence of the stretch reflex are signs of possible neurological or neuromuscular compromise. What to Avoid When Stretching? Many people have never learnt how to stretch correctly. Maybe you have done this yourself: You watch other people stretching in the gym and try to imitate what you see. But who is to say that the person you are watching is doing it right? Here are some of the most common mistakes made while stretching:

• Bouncing. Many people have the mistaken impression that they should bounce to get a good stretch. Bouncing will not help you and could do more damage as you try to push too far beyond the stretch reflex. Every move you make should be smooth and gentle. Lean into the stretch gradually, push to the point of mild tension and hold for a few seconds. Each time you will be able to go a little further, but do not force it.

• Not Holding the Stretch Long Enough. If you do not hold the stretch long enough, you may fall into the habit of bouncing or rushing through your stretch workout. Hold your stretch position for at least 15 to 20 seconds before moving back to your original position.

• Stretching Too Hard. Stretching takes patience and finesse. Each move needs to be fluid and gentle. Do not throw your body into a stretch or try to rush through your stretching routine. Take your time and relax.

• Forgetting Form and Function. Think about your sport or activity. Which muscles will you be using? A stretching routine for a marathon run will be very different from a routine for an hour of lifting weights. Pay attention to the muscles you will need to use in your program and make sure your form for each stretch is attained correctly. Consider the range of motion you will be putting that muscle through. The whole point of stretching is getting your muscles accustomed to moving through a specific range of motion, so if the muscle is not used to going that far, you may end up with an injury.

So, to avoid the stretch reflex and potential damage to your muscles and joints, avoid pain. Never push yourself beyond what is comfortable. Only stretch to the point where you can feel tension in your muscles. This way, you will avoid injury and get the maximum benefits from your stretching.


Role of nervous system in different types of training Both the somatic nervous system and the autonomic nervous system play important roles in controlling and regulating the body’s response to exercise. The somatic nervous system controls voluntary muscles such as the skeletal muscle. The autonomic nervous system controls involuntary muscles such as cardiac and smooth muscles. The role of the somatic nervous system in exercise is straight forward. Skeletal muscle will not contract unless it receives a signal from a motor neuron. The action potential in the motor neuron causes the neuron to release its neurotransmitter that acts as a signal to initiate contraction. Hence, the somatic nervous system directly regulates exercise. The role of autonomic nervous system in regulating exercise is very diverse. The exercise response is mediated primarily through the sympathetic branch of the nervous system. The sympathetic branch promotes responses that prepare the body for exercise. The primary functions of the sympathetic branch of the autonomic nervous system during exercise are to: Enhance cardiorespiratory function

• Heart function o Heart rate and strength of cardiac contraction increase

• Respiratory airways dilate o Increased airflow o Decreased resistance to airflow

▪ improves gas exchange Regulate blood flow and maintain blood pressure

• Coronary vessels dilate, increasing the blood supply to the heart muscle to meet its increased demands

• Blood pressure increases, allowing better perfusion of the muscles and improving the return

of venous blood to the heart

• Peripheral vasodilatation allows more blood to enter the active skeletal muscles

• Vasoconstriction in most other tissues diverts blood away from them and to the active muscles

Thermoregulation - maintain thermal balance

• Increased sweating

• Vasodilatation – increased blood to the skin Increase fuel mobilisation to produce energy

• Glucose is released from the liver into the blood as an energy source

• Adipose cells release fatty acid to be used as fuel Increase mental activity

• Allows better perception of sensory stimuli and more concentration on performance In addition to the activation of the sympathetic nervous system described above, the parasympathetic nervous system is simultaneously inhibited during exercise.


Skeletal System The human skeleton is quite simply a collection of about 206 different shaped bones that align with each other to create a protective framework for the body. The main bones of the upper skeleton are:

• Skull - Cranium, Mandible and Maxilla

• Shoulder girdle - Clavicle and Scapula

• Spine

• Arm - Humerus, Radius and Ulna

• Hand - carpals, metacarpals and phalanges

• Chest - Sternum and ribs The main bones of the lower skeleton are:

• Pelvic girdle - Ilium, pubis and ischium

• Leg - Femur, Tibia and Fibula

• Ankle - Talus and Calcaneus (not shown)

• Foot - tarsals, metatarsals and phalanges


The axial & appendicular skeleton Although we often look at the skeleton as a structure, it can also be divided into two parts; the axial and the appendicular skeleton. The axial skeleton is the central core of the body, while the appendicular skeleton forms the extremities of the arms and legs.

The axial skeleton is the central core of the human body housing and protecting its vital organs and consists of the following three parts (80 bones in total):

• Skull

• Vertebral column o Cervical -7 vertebrae o Thoracic - 12 vertebrae o Lumbar - 5 vertebrae o Sacrum - 5 fused or stuck together bones o Coccyx - four fused vertebrae

• Bony thorax (ribs and sternum) The axial skeleton also provides attachments for muscles and passageways for nerves and blood vessels to pass through. The main purpose of the appendicular skeleton is to allow movement to occur through the joints of our arms and legs. Without the appendicular skeleton, you would be unable to move around and do the activities you do daily. The appendicular skeleton consists of the following six parts (about 126 bones in total);

• Arms

• Legs

• Hands

• Feet

• Pelvic girdle

• Shoulder girdle


Types of bones There are 5 types of bones (in terms of bone shape) in the human body

• Long bones

• Short bones

• Flat bones

• Irregular bones

• Sesamoid bones Long Bones Long bones are some of the longest bones in the body, such as the Femur, Humerus and Tibia, but are also some of the smallest including the metacarpals (fingers). They consist of a shaft - which is the main (long) part and a variable number of endings (extremities), depending on the joints formed at one or both ends of the long bone. Long bones are usually somewhat curved; this contributes to their mechanical strength. Examples include:

• Femur

• Tibia

• Fibula

• Humerus

• Ulna

• Radius Short bones A short bone is one that is cube-like in shape, being approximately equal in length, width, and thickness. The only short bones in the human skeleton are in the carpals of the wrists and the tarsals of the ankles. Short bones provide stability and support as well as some limited motion. Examples include:

• Scaphoid bone (wrist bone)

• Carpal bones

• Cuboid bone (ankle bone)

• Tarsal bones Flat bones Flat bones are strong, flat plates of bone which provide protection to the body’s vital organs and allow for muscular attachment Examples include:

• Cranial bones (protecting the brain) o Frontal bone o Parietal bones

• Sternum (protecting organs in the thorax)

• Ribs (protecting organs in the thorax)

• Scapulae (shoulder blades)


Irregular bones Irregular bones have complicated shapes that cannot be classified as "long", "short" or "flat". Their shapes are due to the functions they fulfil within the body, i.e. provide major mechanical support for the body and protection Examples include:

• Atlas bone

• Axis bone and other vertebrae

• Hyoid bone

• Sphenoid bone

• Zygomatic bones and other facial bones Sesamoid bones The Sesamoid bones are named because they resemble a sesame seed. Sesamoid bones develop in some tendons in locations where there is considerable friction, tension, and physical stress. The presence, location and quantity of sesamoid bones varies considerably from person to person Examples include:

• Patella (knee cap) bone

• Pisiform (smallest of the carpals) bone

• Two small bones at the base of the 1st Metatarsal of the foot Bony landmarks The surfaces of bones have various structural features adapted to specific functions. These features are called bone surface markings, or bony landmarks. Markings are bone features that serve as:

• Sites of attachment for muscles, ligaments, and tendons

• Joint surfaces

• Channels for blood vessels and nerves

Bone Markings: projections Marking Description Example

Condyle Large, smooth, rounded articulating oval

structure Lateral condyle of the Tibia

Crest Narrow, prominent ridge of bone Iliac crest

Epicondyle Raised area on or above a condyle Medial epicondyle of the Humerus

Facet Smooth, nearly flat articular surface Rib facet

Head Bony expansion carried on a narrow neck Head of the Radius

Line Narrow ridge of bone, less prominent than

a crest Linea Aspera of the Femur

Process Any bony prominence Olecranon process of the Ulna

Ramus Arm like bar of bone Inferior ramus of the pelvis

Spine Sharp, slender projection Spine of the scapula

Trochanter Rough, rounded projection (only on Femur) Lesser trochanter of the Femur

Trochlea Smooth, grooved, pulley-like articular

process

Bottom of the Humerus that

articulates with the trochlea notch of

the Ulna

Tubercle Small rounded projection Greater tubercle of the Humerus

Tuberosity Large, rough, rounded projection Tibial tuberosity of the Tibia


Bone Markings: cavities, openings and depressions Marking Description Example

Aditus Entrance to a cavity Laryngeal aditus connects the

pharynx and the larynx

Canal Passageway through a bone Femoral canal located in the anterior

thigh

Fissure Narrow, slit-like opening between bones Superior orbital fissure

Foramen Round or oval opening through a bone Foramen magnum in the occipital

bone of the skull

Fossa Shallow, basin-like depression Olecranon fossa of Humerus

Meatus Canal like passageway External auditory meatus of the

temporal bone

Sinus Chamber with bone usually filled with air Frontal sinus on each side in the

forehead

Sulcus Narrow groove or furrow Central sulcus in the brain

Major Joints Location of joint Common Joint Name Bones of the Joint Actions of the Joint

Neck C1, C2 and skull Rotation

Intervertebral Vertebrae

Flexion, extension,

lateral flexion and

rotation


Shoulder Humerus, scapula and

clavicle

Flexion, extension, horizontal flexion,

horizontal extension, abduction, adduction,

rotation, circumduction,

elevation, depression, protraction and

retraction

Elbow Humerus, Radius and

Ulna Flexion and extension

Wrist Radius, Ulna and

carpals

Flexion, extension, abduction, adduction

and circumduction

Sacroiliac Sacrum and Ilium Very limited range due

to strong ligaments


Hip Femur and pelvis

Flexion, extension, horizontal flexion,

horizontal extension, abduction, adduction,

rotation and circumduction

Knee Femur, patella, Tibia

and Fibula Flexion and Extension

Ankle Tibia, Fibula and

tarsals

Plantar flexion, dorsiflexion, inversion, eversion, supination

and pronation


Cardiovascular System All cells in the body need to have oxygen and nutrients, and they need their wastes removed. These are the main roles of the circulatory system. The heart, blood and blood vessels work together to service the cells of the body. Using the network of arteries, veins and capillaries, blood carries carbon dioxide to the lungs (for exhalation) and picks up oxygen. From the small intestine, the blood gathers food nutrients and delivers them to every cell. Blood Each time the human heart beats, blood rushes out of the muscular pump and winds through approximately 100,000 kilometres of blood vessels. That network of tubes connects every cell of the body, each of them dependent on blood. This vital fluid delivers essential nutrients, carts away waste products, fights infection and heals wounds. Blood is an amazing mixture of three different types of cells suspended in a liquid called plasma. If a person weighs 70 kg, their body contains approximately 5.5 litres of blood.

What is the Role of Blood in Human Body? When you scrape your knee, you bleed red because of red blood cells. A single drop of blood contains millions of these. Shaped like a tiny doughnut with a depression instead of a hole in the centre, each cell rushes through the widest blood vessels and squeezes through the slimmest vessels, known as capillaries. The red colour comes from heme, an iron-based chemical. Heme is a part of the protein haemoglobin, a workhorse chemical that transports oxygen. As red blood cells circulate throughout the body, iron latches onto oxygen brought in by the lungs. Red blood cells deliver oxygen to tissues and organs, such as muscle, the liver and the brain. The table below explains how the structure of a red blood cell is adapted to its function.

Feature Reason

Small size Let’s red blood cells pass through narrow capillaries

Flattened disc shape Provides a large surface area, allowing rapid diffusion of oxygen

Contains haemoglobin Haemoglobin absorbs oxygen in the lungs and releases oxygen in the rest of the body

Does not contain a nucleus Increases amount of space inside the cell for haemoglobin

Blood also contains white blood cells (Leukocytes). These help the body fight disease. If viruses or bacteria enter your bloodstream, white blood cells strike back. Their first punch, called innate immunity, will send in cells that are programmed to attack any kind of invader. Neutrophils, one type of attacking white cell, can gobble up invading bacteria. Other white blood cells called lymphocytes, deliver a second punch in the attack, known as acquired immunity. Once the body recognises an invader, lymphocytes produce antibodies, special chemicals tailored to fight a specific kind of invading microbe or material.


Blood also contains platelets, specialised cells that promote clotting. Platelets move along the walls of blood vessels like border guards, says Keith Hoots, the director of the Division of Blood Diseases and Resources. If platelets reach a break in a blood vessel, such as occurs when you get a cut, they’ll plug the leak. Clotting proteins that circulate in the plasma then glom onto the platelets to form a clot. The transport of hormones, antibodies, nutrients (water, glucose, amino acids, minerals and vitamins) and waste products (carbon dioxide and urea), as well as the maintenance of body temperature; is the role played by plasma, a yellowish fluid that consists of water and other substances such as cholesterol. Plasma also serves as the medium for the transport of the other blood components for them to perform their functions.

The heart and blood vessels The heart is a muscular pump that pushes blood through blood vessels around the body. The heart beats continuously, pumping between 5700 – 8600 litres of blood per day. Blood vessels form the living system of tubes that carry blood both to and from the heart. All cells in the body need oxygen and the vital nutrients found in the blood. Without oxygen and these nutrients, the cells will die. The heart helps to provide oxygen and nutrients to the body's tissues and organs by ensuring a rich supply of blood. Not only do blood vessels carry oxygen and nutrients, but they also transport carbon dioxide and waste products away from our cells. Carbon dioxide is passed out of the body by the lungs; most of the other waste products are disposed of by the kidneys. Blood also transports heat around your body. The heart is a fist-sized organ which lies within the chest behind the breastbone (sternum). The heart sits on the primary muscle of breathing (the diaphragm), which is found beneath the lungs. The heart is considered to have two 'sides' - the right side and the left side. The heart has four chambers - an atrium and a ventricle on each side. The atria are both supplied by large blood vessels that bring blood to the heart (see below for more details). Atria have special valves that open into the ventricles. The ventricles also have valves, but, in this case, they open into blood vessels. The walls of the heart chambers are made mainly of the unique heart muscle. The different sections of the heart must squeeze (contract) in the correct order for the heart to pump blood efficiently with each heartbeat.



The right side of the heart receives blood lacking oxygen (deoxygenated blood) from the body. After passing through the right atrium and right ventricle, this blood is pumped to the lungs. Here blood picks up oxygen and loses another gas called carbon dioxide. Once through the lungs, the blood flows back to the left atrium. It then passes into the left ventricle and is pumped into the main artery (aorta) supplying the body. Oxygenated blood is then carried through blood vessels to all the body's tissues. Here oxygen and other nutrients pass into the cells where they are used to perform the body's essential functions. A blood vessel's primary function is to transport blood around the body. Blood vessels also play a role in controlling your blood pressure and can be found throughout the body. There are five main types of blood vessels: arteries, arterioles, capillaries, venules and veins.

• Arteries carry blood away from the heart to other organs. They can vary in size. The largest arteries have special elastic fibres in their walls. This helps to complement the work of the heart, by squeezing blood along when the heart muscle relaxes. Arteries also respond to signals from our nervous system, either tightening (constricting) or relaxing (dilating).

• Arterioles are the smallest arteries in the body. They deliver blood to capillaries. Arterioles are also capable of constricting or dilating and, by doing this, they control how much blood enters the capillaries.

• Capillaries are tiny vessels that connect arterioles to venules. They have very thin walls which allow nutrients from the blood to pass into the body tissues. Waste products from body tissues can also pass into the capillaries. For this reason, capillaries are known as exchange vessels.


• Groups of capillaries within a tissue reunite to form small veins called venules. Venules collect blood from capillaries and drain into veins.

• Veins are the blood vessels that carry blood back to the heart. They may contain valves which stop blood flowing away from the heart.

Summary of blood vessel function and adaptions

Blood Vessels

Function Adaption

Artery Carry blood away from heart at high

pressure Thick, elastic, muscular walls to withstand

pressure and to exert force

Capillary Allow exchange of materials between

blood and tissues Thin permeable walls

Vein Return low pressure blood to the

heart A large diameter to offer the least flow resistance. Valves to prevent backflow


Cardiac Cycle Heart structure and function can also be described by the Cardiac Cycle: The heart's primary function is to pump blood to the circulation. This is accomplished by a series of contractions (systole) and relaxation (diastole) of the heart muscle, which occurs in a rhythmic or cyclic pattern. How do the heart and blood vessels work?


The following sequence describes the cardiac cycle: Stage 1 - Atrial systole/Ventricular diastole The right atrium, which has been filled with blood from the circulation, contracts and empties blood into the relaxed right ventricle, with the tricuspid valve open. Almost at the same time, blood from the left atrium, which has come from the lungs, empties into the left ventricle, through the open mitral valve. During this time, the valves in the vena cava and the pulmonary vein are closed to prevent the backflow of blood. Stage 2 - Ventricular systole/atrial diastole After contraction, the atria relax, the atrioventricular valves close, and the ventricles simultaneously contract with a higher pressure to pump blood into the lungs, via the pulmonary artery, and the systemic circulation, via the aorta. Stage 3 - Ventricular diastole/atrial systole After pumping out blood, the ventricles relax, and the pulmonary and aortic valves close to prevent backflow. Refilling of the right and left atria occurs as they relax and start the whole cycle once again. Oxygen demands of fitness activities Regardless of whether a person is lifting weights, or performing cardiovascular exercise (e.g. swimming), an exercising body will require more oxygen than a body at rest. As the muscles begin to work harder during exercise, their demand for oxygen increases. This happens because oxygen is needed to burn calories more efficiently. Since the blood picks up oxygen in the lungs, and the demand for oxygen increases during exercise, the lungs must work harder. The increased demands on the lungs include supplying the increased oxygen needed by the exercising muscles as well as removing excess carbon dioxide produced by working muscles. Therefore, you breathe more heavily and frequently during exercise. With a faster breathing rate, more oxygen is picked up at the lungs for delivery to the working muscles. If the muscles do not receive enough oxygen during exercise, a shift to anaerobic metabolism occurs. This results in the production of lactic acid. Lactic acid can affect the delivery of oxygen by changing how oxygen and carbon dioxide bind to haemoglobin molecules in the blood.

Relationships between exercise intensity and circulatory and ventilator responses At the onset of exercise, the energy requirements of the skeletal muscles increase instantly. This increased metabolic demand places additional stress on the cardio-respiratory system to deliver oxygen to the working tissue cells and to remove carbon dioxide and other waste products from the tissue cells. To get more oxygen to the active muscle cells at the onset of exercise, blood flow to the tissues must increase. This means that the heart must pump more blood. Therefore, cardiac output is increased. An increase in cardiac output produces a proportionate increase in the circulation of oxygen. Systolic blood pressure, stroke volume and heart rate also increase rapidly at the onset of exercise but will reach a steady state (remain constant) within approximately 2 minutes. Diastolic blood pressure remains relatively unchanged, but arteries feeding the working muscle dilate (resistance decreases). This rapidly increases blood flow to active muscle in proportion to other organ tissues. Other blood vessels feeding tissue with less metabolic demand constrict. The other major cardiovascular response to short-term, light to moderate aerobic exercise other than increased blood flow is the increased ability of active tissue to extract more oxygen already


carried in the blood. This effect is reflected by an expanded a-v O2 difference. This is a measurement of the difference in the amount of oxygen carried by the arterial and venous blood. A greater a-v O2 difference means that more oxygen is being extracted from the blood resulting in lower oxygen concentrations in the venous blood. During long-term, moderate to heavy aerobic exercise, cardiac output, stroke volume, heart rate, systolic blood pressure increases rapidly. Once steady state is achieved, cardiac output remains relatively constant owing to the downward drift of stroke volume and the upward drift of heart rate. Systolic blood pressure and resistance may also drift downward during prolonged, heavy work. This cardiovascular drift is associated with rising body temperature. During incremental exercise to maximum, cardiac output, heart rate, systolic blood pressure increases in a rectilinear fashion with increasing workload. Stroke volume increases initially and then plateaus at a workload corresponding to approximately 40–50% of VO2 max. Diastolic blood pressure remains relatively constant. Resistance decreases rapidly with the onset of exercise and reaches its lowest value at maximal exercise. During exercise, pulmonary ventilation increases to augment oxygen supplies to working muscle and to remove waste products of metabolism. The volume of air breathed each minute is referred to as minute volume. Minute volume is the product of the breathing rate times the tidal volume. Tidal volume (TV) describes the volume of air moved during either the inspiratory or expiratory phase of the breathing cycle. Exercise increases both the breathing rate and the tidal volume, thus increasing minute ventilation. Exercise minute ventilation can increase about 17-20 times the resting value. This increase allows more oxygen to reach muscles that need it and to have a supply of oxygen in the blood to be used. If the intensity of the exercise continues to rise, the amount of oxygen able to be taken will eventually reach its maximal point, and VO2 max will be reached, this means the maximal level for oxygen consumption has been reached.

Respiratory System Mechanics of breathing The respiratory system is the system in the human body that enables us to breathe. The act of breathing includes: inhaling and exhaling air, into and from the body; the absorption of oxygen from the air to produce energy; the discharge of carbon dioxide, which is the by-product of the process. The action of breathing in and out is due to changes of pressure within the thorax, in comparison with the outside The act of breathing takes place in two phases:

• Inspiration (inhalation)

• Expiration (exhalation) Inspiration and expiration involve the following muscles:

• Rib muscles = the muscles between the ribs in the chest

• Diaphragm muscle Muscle movement – the diaphragm and rib muscles are constantly contracting and relaxing (approximately 16 times per minute), thus causing the chest cavity to increase and decrease.


Inspiration Inspiration (inhalation) is the process of breathing in, by which air is brought into the lungs. It occurs with the help of diaphragm muscles. The muscles of the diaphragm contract which move it in a downward direction. Due to this, the volume of the chest cavity increases, and it results in a decrease in air pressure inside the chest cavity. Now, the oxygenated air present outside the body being at high pressure, flows rapidly into the lungs by passing through the nasal cavity, pharynx, larynx, trachea, bronchi and bronchioles. Expiration After the exchange of gases in the lungs, the air must be expelled. Expulsion of the air from the lungs is called expiration (exhalation). Expiration is largely a passive process that depends more on the natural elasticity of the lungs than on muscle contraction. This happens when the muscles of diaphragm relax and come back to their original position. This decreases the volume of the chest cavity, due to which our chest cavity contracts and pushes out carbon dioxide containing foul air through bronchi, trachea, larynx, pharynx, nasal cavity and nostrils. When we breathe out, not all the air in the lungs gets expelled. Some of it remains in the lungs. This keeps the lungs from collapsing and allows more time for the exchange of gases.

Respiratory volumes and relationships to fitness levels and exercise Lung Volumes and Capacities The amount of air contained in the lungs during ventilation can change considerably depending on what muscles are driving airflow and how forcefully they contract. The different amounts of air drawn into or out of the lungs by contracting different groups of muscles are called primary lung volumes. Different combinations of the primary lung volumes (sum of two or more primary lung volumes), in turn, provide us with lung capacities, which define either how much air is present in the lungs or how much air can be moved by the lungs under specific situations. Total Lung capacity is dependent upon many factors such as weight, sex, age and activity. For example, females tend to have a 20-25% lower capacity than males. Tall people tend to have a larger total lung capacity than shorter people. Heavy smokers have a drastically lower TLC than non-


smokers. Some people, such as elite athletes, have a TLC well above average. While the average TLC is about 5.8 litres (5800 cm3), it varies from one person to the next Primary lung volumes

Lung Volume Definition Average Values (mL)

Male Female

Tidal Volume

(TV)

• Volume of air inspired or expired per breath at

rest

• Tidal volume increases with activity to

accommodate increased need for gas exchange

600 500

Inspiratory

Reserve Volume

(IRV)

• The amount of extra air inhaled (above tidal

volume) during a deep breath.

• IRV decreases with exercise

3000 1900

Expiratory

Reserve Volume

(ERV)

• The amount of extra air exhaled (above tidal

volume) during a forceful breath out

• ERV decreases when exercising

1200 800

Residual Volume

(RV)

• The amount of air left in the lungs following a

maximal exhalation

• There is always some air remaining to prevent

the lungs from collapsing

1200 100

Primary lung capacities

Lung Capacity Definition Average Values (mL)

Male Female

Inspiratory

Capacity (IC)

• The total volume of air a person can inspire

after a normal expiration

• IC = IRV + TV

3600 2400

Expiratory

Capacity (EC)

• The total volume of air a person can expire after

a normal inspiration

• EC = TV + ERV

1600

Functional

Residual

Capacity (FRC)

• The volume of air that will remain in the lungs

after a normal expiration

• FRC = ERV + RV

4800 3200

Vital Capacity

(VC)

• The volume of air that is exhaled by a maximal

expiration following a maximal inspiration.

• VC = IRV + TV + ERV

4800 3100

Total Lung

Capacity (TLC)

• Total volume of air accommodated in the lungs

at the end of a forced inspiration

• TLC = IRV + TV + ERV + RV

6000 4200

Regular exercise leads to numerous and varied physiological changes that are beneficial from a health standpoint. If you're wondering whether you'll change your total lung capacity or forced vital capacity by putting in a single hard day at the gym, the answer is no. Exercise doesn't alter lung capacity or the amount of oxygen the lungs can take in during a single breath. Studies comparing TLC and FVC show little difference between regular exercisers and non-exercisers. So even though people often report feeling out of breath or winded during exercise, it is unlikely that pulmonary function limits their ability to exercise; unless they have a disease that specifically impairs lung function such as asthma, bronchitis or emphysema. Over time though, there will be changes to the lungs' efficiency that can help a person breathe easier.


Breathing Rate Increases So, what happens during exercise? The most significant change during a moderate to vigorous-intensity workout is the number of breaths taken per minute. The muscles need more oxygen when they're working, which will cause an increase in the "breathing rate." While at rest, a person may take about 15 breaths per minute, but when they work out, that rate more than doubles to between 40 and 50 breaths in a minute. As a person exercises harder and harder, their breathing rate and heart rate will increase to a certain point and then won't go any higher. The point at which your body can no longer use any more oxygen is called your VO2 max. Tidal Volume Increases Not only does a person’s breathing rate increase during exercise, but they'll also start taking in larger gulps of air. This, as you know, is called the "tidal volume”. Tidal volume increases by as much as 15% during exercise. Total lung capacity doesn't change much for an individual over time, even with changes to fitness levels. And during an individual workout, the total capacity isn't changing -- though the amount of air they are currently consuming has gone up. As the lungs take in more air with each breath, the heart also increases its output, pumping more blood with each stroke. Exercise Adaptations If a person has been working out for a while and they may have noticed that they are not breathing quite as heavily as they once did, this is the body's gradual adaptations to exercise. First, the person is becoming more efficient at using oxygen. People who work out regularly have a higher blood volume and are better able to draw the oxygen from their blood to their muscles. The muscles also get more efficient at removing the waste products of exercise, namely carbon dioxide. Additionally, as a person continues to exercise, their breathing muscles, including their diaphragm and intercostals, are getting stronger and making breathing easier.

Energy systems, pathways and substrates and relevant recovery options The human body needs energy to function, but where does this energy come from? Ultimately, the energy that keeps us moving comes from the food we eat. However, we cannot use energy directly from food. It must first be converted into adenosine triphosphate (ATP). Adenosine triphosphate is the immediate useable form of energy used for all cellular function. The body does store a minimal amount of ATP within the muscles, but the majority is synthesised from the foods we eat. After food is digested, the carbohydrates, protein and fat break down into simple compounds - glucose, amino acids and fatty acids - which are absorbed into the blood and transported to various cells throughout the body. Within these cells, and from these energy sources, ATP is formed to provide fuel. The body is not able to store a significant amount of ATP, and you will almost always be requiring a continuous supply. Therefore the body has developed 3 different systems to supply cells with the necessary ATP to fuel energy needs

• ATP-PC system (immediate source)

• Anaerobic lactate system (somewhat slow, uses carbohydrates)

• Aerobic system (slow, uses either carbohydrate or fat) ATP-PC system ATP and phosphocreatine (PC) compose the ATP-PC system, also sometimes called the phosphagen system. It is immediate and functions without oxygen. It allows for up to approximately 12 seconds (+ or -) of maximum effort. During the first few seconds of any activity, stored ATP supplies the


energy. For a few more seconds beyond that, PC cushions the decline of ATP until there is a shift to another energy system. It is estimated the ATP-PC system can create energy at approximately 36 calories minute. Anaerobic lactate system The lactate system is the predominant energy system used for all-out exercise lasting from 30 seconds to about 2 minutes and is the second-fastest way to resynthesise ATP. During glycolysis carbohydrate—in the form of either blood glucose (sugar) or muscle glycogen (the stored form of glucose)—is broken down through a series of chemical reactions to form pyruvate (glycogen is first broken down into glucose through a process called glycogenolysis). For every molecule of glucose broken down to pyruvate through glycolysis, two molecules of usable ATP are produced. Thus, very little energy is produced through this pathway, but the trade-off is that you get the energy quickly. Once pyruvate is formed, it has two fates: conversion to lactate or conversion to an intermediary metabolic molecule called acetyl coenzyme A (acetyl-CoA), which enters the mitochondria for oxidation and the production of more ATP. Conversion to lactate occurs when the demand for oxygen is greater than the supply (i.e. during anaerobic exercise). Conversely, when there is enough oxygen available to meet the muscles’ needs (i.e. during aerobic exercise), pyruvate (via acetyl-CoA) enters the mitochondria and goes through aerobic metabolism. When oxygen is not supplied fast enough to meet the muscles’ needs (anaerobic glycolysis), there is an increase in hydrogen ions (which causes the muscle pH to decrease; a condition called acidosis) and other metabolites (ADP, Pi and potassium ions). Acidosis and the accumulation of these other metabolites cause several problems inside the muscles, including inhibition of specific enzymes involved in metabolism and muscle contraction, inhibition of the release of calcium (the trigger for muscle contraction) from its storage site in muscles, and interference with the muscles’ electrical charges. Because of these changes, muscles lose their ability to contract effectively, and muscle force production and exercise intensity ultimately decrease. Aerobic System The aerobic system is the most complex of the three energy systems. The metabolic reactions that take place in the presence of oxygen are responsible for most of the cellular energy produced by the body. However, aerobic metabolism is the slowest way to resynthesise ATP. Oxygen, as the patriarch of metabolism, knows that it is worth the wait, as it controls the fate of endurance and is the sustenance of life. “I’m oxygen,” it says to the muscle, with more than a hint of superiority. “I can give you a lot of ATP, but you will have to wait for it.” The aerobic system—which includes the Krebs cycle (also called the citric acid cycle or TCA cycle) and the electron transport chain—uses blood glucose, glycogen and fat as fuels to resynthesise ATP in the mitochondria of muscle cells. Given its location, the aerobic system is also called mitochondrial respiration. When using carbohydrate, glucose and glycogen are first metabolised through glycolysis; with the resulting pyruvate used to form acetyl-CoA, which enters the Krebs cycle. The electrons produced in the Krebs cycle are then transported through the electron transport chain, where ATP and water are produced (a process called oxidative phosphorylation). Complete oxidation of glucose via glycolysis, the Krebs cycle and the electron transport chain produces 36 molecules of ATP for every molecule of glucose broken down. Thus, the aerobic system produces 18 times more ATP than does anaerobic glycolysis from each glucose molecule. Fat, which is stored as triglyceride in adipose tissue underneath the skin and within skeletal muscles (called intramuscular triglyceride), is the other primary fuel for the aerobic system and is the largest store of energy in the body. When using fat, triglycerides are first broken down into free fatty acids


and glycerol (a process called lipolysis). The free fatty acids, which are composed of a long chain of carbon atoms, are transported to the muscle mitochondria, where the carbon atoms are used to produce acetyl-CoA (a process called beta-oxidation). Following acetyl-CoA formation, fat metabolism is identical to carbohydrate metabolism, with acetyl-CoA entering the Krebs cycle and the electrons being transported to the electron transport chain to form ATP and water. The oxidation of free fatty acids yields many more ATP molecules than the oxidation of glucose or glycogen. For example, the oxidation of the fatty acid palmitate produces 129 molecules of ATP. No wonder clients can sustain an aerobic activity longer than an anaerobic one!

Reference - http://www.ideafit.com/fitness-library/the-three-metabolic-energy-systems

Why are the energy systems important? The energy systems are what enable every cell, tissue and organ in our bodies to function and survive. Without enough energy being continuously supplied through the energy systems, the body would literally shut down, cease to function and die! Essentially the body is like a machine and like any machine it needs energy to power it, for example; A car without petrol in the tank is just a piece of metal that can't do anything. With fuel, the car can come to life and go from 'A to B’. However, understanding exactly how energy systems function and all the biochemical processes involved can be very confusing. Is it really that important to be able to explain the chemical breakdown of the oxidative Krebs cycle or anaerobic glycolysis? Not really. You need to understand the basics of how energy is generated and how the energy systems work and interact with each other. Why? This will help ensure that you are advising the right type of fuels for your clients to consume. As well as designing and prescribing the correct type of training, and applying the variables (sets, reps, rest intervals, etc.) correctly to ensure your clients achieve their specific goals by design rather than by accident. The energy systems and fitness When a person lifts weight at the gym or goes for a run, there are many body systems involved that work together for this to be possible, for example;

• Going for a 30-minute run requires the following; o Nervous system - memory of running movement patterns, action potentials to

skeletal, cardiac and smooth muscle o Muscular system - contraction and force production of leg muscles to run o Respiratory system - inhalation of O2 and exhalation of CO2 o CV system - heart and blood vessels transport O2 and nutrients to muscles and

remove CO2 and waste products Energy is continuously required by all these systems for them to work. For this reason, the three energy systems work together continuously. All energy systems are available and “turn on” at the outset of any activity. What determines whether one (or two) is relied upon is the effort required? Duration and intensity are the two variables that will determine which system is most active at any given time. When exercise begins, energy will come from the anaerobic energy systems, the initial 10 seconds or so are almost exclusively through the ATP-PC system. As exercise continues, the anaerobic systems become depleted (due to the limited stores of ATP, PC and glycogen) and the aerobic system becomes increasingly dominant. The higher the intensity of the exercise, the quicker the anaerobic systems will be depleted. For exercise to continue, once the anaerobic systems have

http://www.ideafit.com/fitness-library/the-three-metabolic-energy-systems


become significantly depleted, the intensity of exercise needs to drop to a level that allows the aerobic system to provide enough energy. When it comes to working with clients and developing appropriate exercise programmes that help them achieve their goals, it is vital to consider the energy systems. Understanding which energy system will predominantly be used during training is crucial to ensuring that they are prescribed the correct duration and intensity of exercise. Recovery Procedures for speeding recovery from exercise generally are either active or passive. With active recovery (often termed “cool-down), a person performs submaximal exercise, believing that continued physical activity in some way prevents muscle cramps and stiffness and overall recovery. With passive recovery, a person usually lies down, presuming the total inactivity reduces the resting energy requirements and thus frees oxygen to fuel the recovery process. Modifications of passive recovery have included massage, cold showers etc. The ATP-PC system recovers as the creatine in the cell connects to the free phosphates again, storing them as PC to be used when they are needed again. This process takes up to 2 minutes for complete recovery but can be half restored at around the 30 second mark. When exercising aerobically at or close to the lactate threshold (lactate system), a build-up of lactate will contribute to fatigue. During recovery, it becomes increasingly important to rid the body of the lactate as quickly as possible. It has been demonstrated that active recovery is more effective in reducing lactate levels post exercise than passive recovery. This is due to the increased blood flow to the muscle during active recovery, enhancing the transport of lactate from the muscle to the removal sites. The clearance of lactate during recovery is due to its oxidation to carbon dioxide and water; it is then transported to the liver where it is converted back to glucose. Its conversion to glycogen in the muscle via gluconeogenesis and its role in providing energy for the recovery process. The optimal level of recovery exercise ranges between 30 and 45% VO2 Max for bicycle exercise and 55 to 60% VO2 Max when recovery involves running. These intensities can result in between 40-50% of lactate removal occurring within 15 minutes of recovery. Recovery for the aerobic system is about restoring fuel stores to their pre-exercise levels. This requires the ingestion, digestion and transportation of the fuel and can take between 12 and 48 hours depending on the intensity and duration of the aerobic performance. Passive procedures facilitate recovery because any additional exercise will only serve to elevate metabolism and delay recovery. Process of recovery The process of recovery once fatigue has occurred requires oxygen. Pyruvic acid in the presence of oxygen will be converted to acetyl coenzyme A, which is then broken down through the Krebs cycle to produce more ATP. Without oxygen, it is converted to lactate and removed from the muscle and taken to the liver to be converted into glucose. This process can take anywhere between 30 and 60 min.


Thermoregulation of the human body Thermoregulation is a process that allows the body to maintain its core internal temperature. All thermoregulation mechanisms are designed to return the body to homeostasis. This is a state of equilibrium. A healthy internal body temperature falls within a narrow window. The average person has a baseline temperature between 37°C and 37.8°C. Many factors can affect the body’s temperature, such as spending time in cold or hot weather conditions. Factors that can raise internal temperature include:

• hot, humid conditions

• fever

• exercise

• digestion Factors that can lower internal temperature include:

• being exposed to cold weather or wearing soaked or wet clothing for a long time

• drug use

• alcohol use

• metabolic conditions, such as an under-functioning thyroid gland Control mechanisms The body’s temperature is monitored by the brain. If a person becomes too hot or too cold, the brain sends nerve impulses to the skin, which has three ways to either increase or decrease heat loss from the body’s surface: 1. Hairs on the skin trap more warm air if they are standing up, and less if they are lying flat. Tiny

muscles in the skin can quickly pull the hairs upright to reduce heat loss or lay them down flat to increase heat loss.

2. If the body is too hot, glands under the skin secrete sweat onto the surface of the skin, to increase heat loss by evaporation. Sweat secretion stops when body temperature returns to normal.

3. Blood vessels supplying blood to the skin can swell or dilate - vasodilation. This causes more heat to be carried by the blood to the skin, where it can be lost to the air. Blood vessels can shrink down again - vasoconstriction. This reduces heat loss through the skin once the body’s temperature has returned to normal.

Muscles can also receive messages from the brain when you are cold. They respond by shivering, which warms you up.


If you become too hot or too cold, there are several ways in which your temperature can be controlled. They involve sweating, shivering, skin capillaries and hairs. Too hot

• sweat glands in the skin release more sweat when we get too hot. This evaporates, removing heat energy from the skin

• vasodilation occurs. Blood vessels leading to the skin capillaries become wider (dilate), allowing more blood to flow through the skin, and more heat to be lost.

Too cold

• muscles contract rapidly, and we shiver when we're cold. These contractions need energy from respiration, and some of this is released as heat.

• vasoconstriction occurs - blood vessels leading to the skin capillaries become narrower (constrict), letting less blood flow through the skin and conserving heat in the body.

The hairs on the skin also help to control body temperature. They lie flat when we are warm and rise when we are cold. The hairs trap a layer of air above the skin, which helps to insulate the skin against heat loss.


Posture Posture is simply the position in, which the body is held against gravity while standing, sitting, lying down, or performing other weight-bearing activities (i.e. lifting in the gym or running). Posture is, therefore, an ever-changing dynamic process, which changes from minute-to-minute.

The spinal curves

The spine has natural curves that form an S-shape. Viewed from the side, the cervical and lumbar spines have a lordotic; a slight inward curve and the thoracic spine has a kyphotic’; a gentle outward curve. The spine's curves work like a coiled spring to absorb shock, maintain balance, and to facilitate the full range of motion throughout the spinal column.

Posture becomes important when attempting to decrease the stress experienced by various structures in the body (i.e. discs, joints and muscles), increase flexibility and strength, improve sporting performance, and overall well-being in day to day activities. For some people, this might mean a reduction in excess spinal curvature, and for others, it might mean trying to increase spinal curvatures.

As posture is an integral part of everyday life and the safe execution of exercises, fitness professionals should, therefore, always look at a client’s posture and make necessary adjustments or program exercises around this.

Acting within their scope of practice; fitness professionals can perform a general static postural analysis and functional movement analysis. Then use these results to choose appropriate flexibility and strengthen exercises to help the client reach their goals without causing any damage or exacerbate current injuries. No fitness professional has the scope to diagnose or perform any form of manual therapy work on their clients. Failure to do so will breach the code of conduct and lead to negligence.

For general postural changes, both specific (i.e. muscles) and non-specific (i.e. general movements) flexibility exercises can be used, and the strengthening exercises must meet general recommendations (see topic Programming for Fitness Instruction). It’s also important the client is practising using good posture throughout the day (e.g. sit upright in a chair instead of slouching). Other means, such as; soft tissue work, foam rolling, and various other means could be used to improve posture.


In other words, a fitness professional should aim to improve a client’s ability to stand, walk, sit and lie in positions where the least strain is placed on supporting muscles and ligaments during movement or weight-bearing activities. Furthermore, during exercise sessions, the fitness professional should always use reactive cues and proprioceptive feedback (i.e. use of stick or dowel to teach positions) to reinforce proper movement further.

Ideal Posture

Even though there is no such thing as a universally ideal posture; human beings all have different builds. Some key aspects must be remembered when aiming to achieve a better posture and the many health benefits that come with such (i.e. reduced tension, better breathing, improved sporting performance, and so on).

Even though the evidence isn’t clear cut on exactly why a less optimal posture occurs, it’s important to be aware of the signs of poor posture to prevent or manage future injuries or damage possibly. Possible causes could range from disturbed vision, muscle weakness, clinical muscle imbalances, direct trauma and negative self-belief, to work-related stress factors, poor sleep and excess use of technology (i.e. driving, iPads and so on).

There are clear indicators of poor posture when looking at a client from either the back or side views.

When examining clients from the back, a fitness professional might find;

• One ear lower than the other

• Head turned to the right or left

• Shoulders higher on one side

• Spine curved to the side

• One hip higher than the other

• Feet turned in or out

When examining clients from the side, a fitness professional might find;

• Head sits forward

• The upper back curve is flat

• Shoulders are rounded

• Stomach sticks out

• The lower back is too curved

The below acronym (POSTURE) is an excellent reminder on what to do to ensure a good posture is maintained;

Pelvis in neutral, with weight distributed

On the whole foot

Stable joints

Tight abdominals

Upright ribs

Retracted shoulders and

Ear in line with shoulder

Documents

Certificate III in Fitness