sport and recreation PDF

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U N I T U N I T

2

The active

bodyOUTCOME 1

Explain how the musculoskeletal, cardiorespiratory and

energy systems function during physical activity, including

how energy systems work together to enable activity to occu

OUTCOME 2

Explain the impact of participation in physical activity on the

health of selected population(s) and analyse factors affectingparticipation in physical activity.


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CHAPTER 5

Musculoskeletal

system

C H A P T E R 5

The study of the body’s muscles and bones is centralto any secondary physical education student. Thesetwo body systems are closely inter-related. Onecannot function without the other. When musclescontract, bones, via their joints, must move or bodymovement is impossible. The major bones andmuscles figure in everyday sport reports in the media

and are crucial in ensuring all fitness programs arespecific to desired outcomes. The different musclefibre types, the range of muscle movements and howthey are stimulated to move by the central nervoussystem are both interesting and essential learning forthe developing sportsperson.


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C H A P TE R 5

Assessment tasks Topics Page

Written reports Organs protected by bones (activity 1)Types of bones and muscles (activity 2)Action muscles in sport (activity 9)

161162179

Oral presentation The human spine — personal stories (activity 3) 165

Laboratory report Dissection of lamb shank (activity 5) 168

Data analysis Heart rate investigation (activity 7) 173

Multimedia presentation Interesting facts search (activity 6) 169

Report on participation inphysical activity

Primary school activity patterns (activity 4) 166

Tests Muscle insertion and origin knowledge (activity 8)Review questions

178182

Assessment tasks

After completing this chapter, students should be able to:

• identify the major muscles and bonesin the human body, the roles that thetwo systems play in the body, and themain muscle origins and insertions

• describe the major joint systems in the body• explain the different types of muscle

contractions, and how muscles areactivated via the CNS

• analyse the importance of activity forbone development, the components ofa typical joint system, and the ways thatmuscles are used in sport

• outline the different types of muscle andthe two major types of muscle fibres

• outline the acute changes to the muscularsystem during physical activity.


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Skeletal system

FunctionsThe skeletal system has four main functions in bodily health. Bodymovement is the most important function to understand in physical educa-tion, but you also need to be aware of the other functions of this dynamic

system.

Body movement

The human body has over 200 bones, all of which provide sites for muscleattachment. When a muscle contracts, it moves the bone to which it isattached and thus creates movement. Any irregularity on a bone’s surfaceprovides a possible site for a muscle attachment. Figure 5.1 illustrates thesites for the biceps muscle attachments.

Figure 5.1:

Bones offer ready attachments

for muscle tendons.

Support and protection

The skeleton provides solid support for the body and helps battle the forcesof gravity. Everyone has a solid skeleton, but the differences in people’sposture indicate the interdependence of the skeletal and muscular systemsin maintaining correct posture.

The strong protective skeletal layer protects many vital body organs.This is particularly evident when the rib cage is examined (figure 5.2). Thisnaturally enclosing shell effectively protects the heart, lungs and kidneys

from all but the most traumatic of injuries.There are two main types of bone tissue:• compact bone, which is found in the shaft or diaphysis of the long

bone. This comparatively solid bone surrounds the cavity of the long bone, offering an extremely strong structure that gives the body its rigidframework. Collagen is a central ingredient in providing compact bonerigidity and tensile strength (as it is with cancellous bone). In someways the skeleton is stronger and more durable than concrete ; and

• cancellous bone (also described as spongy bone, being less dense thancompact bone), which provides some of the shock absorption requiredat the end of long bones or at the edges of more irregular bones.

Two origins

of biceps


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Key knowledge• The musculoskeletal system:

movement terminology, major

joints and joint action, major

muscles, characteristics and

functions of skeletal muscle

fibre types, nervous control

of muscles, the mechanics

of breathing, types of

muscular contractions

Key skill• Use correct terminology

to describe the role of the

body systems at rest

and when undertaking

physical activity.

Written report

Organs protected by bones

Study figure 5.2. The rib cageprotects the heart. List otherimportant body organs that theskeleton protects to some extent.

Activity 1

Figure 5.2:

Skeletal bones from the

front of the body

Skull

Rib

Humerus

Ulna

Pelvic

girdle

Femur

Fibula

Tibia

Tarsals

Humerus

Vertebral

column

Carpals

Metacarpals

Phalanges

Patella

Metatarsals

Phalanges

Clavicle

Scapula

Sternum

Pectoral

girdle

Mineral storage site

Bone tissue efficiently stores a number of minerals that are important forhealth. Calcium, phosphorus, sodium and potassium all contribute tothe health and maintenance of bone tissue as well as carrying out other

roles in the body (see chapter 11, Live It Up 2, second edition, for furtherinformation).

Production of blood cells

Essential production of new red blood cells occurs within the cavity of long bones. Production levels are high during growth years, diminishing as ageincreases and the need for high rates of red blood cells decreases. Such cellsare essential for oxygen transportation throughout the body. Haemoglobin, a protein inside red blood cells, transports oxygen molecules from thelungs to the body. Much of an adult’s bone cavity is filled with yellow bonemarrow which is a source of long-term energy.

Radius

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Carpals (wrist)(a)

Radius

Ulna

Types of bonesThere are five types of bones, distinguished by their shape.1. Short bones (figure 5.4[a]) are roughly cubical, with the same width and

length, for example, the carpals of the wrist and the tarsals of the foot.2. Long bones (figure 5.4[ b]) are longer than they are wide,

and they have a hollow shaft containing marrow (figure 5.3),for example, femur, phalanges and humerus.

3. Sesamoid bones (figure 5.4[c]) are small bones developed in tendonsaround some joints, for example, the patella at the knee joint.

4. Flat bones (figure 5.4[d]) provide flat areas for muscle attachment andusually enclose cavities for protecting organs, for example, scapula, ribs,sternum and skull.

5. Irregular bones (figure 5.4[e]) have no regular shape characteristics,for example, vertebrae and bones of the face.

Figure 5.4:

Exam ples of bone ty pes

( a ) Short bones —

the car pals of the wr ist ;

( b ) A lon g bone — the humerus ;

( c ) A sesamoid bone — the patella ;

( d ) A fl at bone — the sca pula ;

( e ) An irre g ular bone — a vertebra

Cartilage

Head of femur— spongy bonecontaining red marrow, wherered blood cellsare made

Shaft —hard or

compact bone, which gives the bone itsshape and strength. (It contains calcium and phosphorus.)

Cavity containingbone

marrow

Cartilage(d)







of muscles, the mechanic of

breathing, types of muscular

contractions

Key skill• Use correct terminology to

describe the role of the body

systems at rest and when

undertaking physical activity.

Written report

Types of bones and muscles

Look at figure 5.4 and read the information on this page.Use figure 5.2 and label as many of the bones as you can:

long, short, sesamoid, flat or irregular. Once you have studiedthe ‘Muscular system’ section of this chapter, also nameand sketch on to figure 5.2 the 10 major muscle groups.Use the muscle diagrams in figure 5.15 for reference.

Activity 2

Epiphysealplates

Vertebralprocesses

(e)

(b)

Femur

Fibula

Tibia

Patella(kneecap)

(c)

Figure 5.3:

A lon g b

one — the femur

Largeflat surface

area formuscle

attachments

and protectionof organsbeneath them

Vertebralbody

Spinal canal — protects

the spinal cord

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Dietary influence

Some vitamins and minerals are essential in maintaining skeletal health.A properly balanced diet provides adequate supplies of these components(see chapter 11, Live It Up 2, second edition, for further information).• Vitamin A is important for optimal bone development

and tooth formation. It has been proven influential in healthyskin growth and repair. Sources of vitamin A are liver, kidneys,

milk fat, egg yolks and dark green and yellow vegetables.• Vitamin C is important for collagen production which provides bones

with tensile strength and works to bind the salt crystals which form thecement-like mass of the skeleton. Sources of vitamin C are citrus fruits(oranges, lemons, limes, grapefruit) and all types of vegetables.

• Vitamin D influences the rate of growth in developing bones andpromotes calcium absorption from the digestive tract. Sources of vitaminD are milk, fish-liver oils and safe exposure to the sun’s ultra-violet rays.

• Calcium helps create the bone rigidity which is so important to the bone’s role of structural support. The stores of calcium in bones

fluctuate with the body’s general demand for thisimportant mineral. Calcium is required for other

body functions such as muscle contractionand the operation of the nervous system,

so the skeletal supplies rise and falldepending on the body’s calls

for extra supplies.

Figure 5.7:

F ood sources r ich in

bone-nurtur in g nutr ients

164CHAPTER 5 LIVE IT UP 1


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of muscles, the mechanics of


contractions

Key skill• Use correct terminology

to describe the role of the

body systems at rest

and when undertaking

physical activity.

Oral presentation

The human spine — personal stories

Read and discuss the article in figure 5.8.1. Discuss any stories that classmates may have regarding back or

spinal problems encountered already in their lives. These storiescould be sparked by some of the f acts presented in the article.

2. Af ter school discuss these issueswith the adultsin your immediate and maybe your extended f amilies.Take notes on any relevant back or spinal stories they may have.

3. Are bad back stories more common as people age? Think of some reasons f rom the knowledge you havepicked up so f ar.

4. Do an Internet search and take notes on any interesting sitesor news that you can locate on the topic.

5. Present your findings to the class.

Activity 3

1. The human spine, a uniquevertical structure that allows usto walk on two f eet rather thanfour, has 26 stacked verte brae andat some stage in lif e, one of thesewill cause enough pain to sendyou to a doctor.A bout 80 per cent

of usw

ill suff er back pain becauseof poor posture.

2. In the embryonic stage of development, the spine is longerthan the body and soon af ter birth, it is straighter than it ever will beagain. When a ba by sits up andholds its head erect, it develops thefirst characteristics cervical curve

of the spine. When the child beginsto stand, the second lumbar

curve completes theS-shape of the spine, which brings the

head and torso into vertical

alignmentwith thef eet.

3. The spine is one of the firststructures of the body to show signs of ageing. According to recent research, children who f ailto crawl eff ectively, or who areforced to walk too early, are at risk of later spinal dysf unction. So, too, are people who sit for too long.

4. During the day, the downwardpressure of gravity on verte braldiscs reduces height by up to 2.5 centimetres. This is exacer bated by long periods of sitting which, surprisingly, is one of the moststressf ul things you can do to yourspine as it puts four times morepressure on discs than standing.Conversely, astronauts in zero gravity grow by a boutsix centimetres.

5. Sitting and many other activitiesput people at risk of developing back pain but stretching, bikeriding, rowing, yoga, swimming, toe touching and ‘curls’ areconsidered good maintenanceha bits for healthy, flexi ble spines.

Certainly, most back specialistsadvise that you should never sitlonger than 20 minutes in a fixedposition without stoppingfor a stretch break.

Compiled by Jennifer Verrall

The Knowledge

Five things you didn’t know about …

The human spine

Figure 5.8

Source:

The Age , Education Age ,

13 November 2001.

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How activity affects skeletal health

You should aim for a balance when deciding on levels and types of physicalactivity, noting each activity’s influence on skeletal growth and health.Manystudies have positively linked weight-bearing activity (such as running and

jumping) with the healthy rates of bone growth in length and width. Thiscorrelation has been especially evident in active versus inactive children.

The accuracy of these studies is highlighted when the high bone densi-

ties of athletes in resistance-based sports are compared with the lower bonedensities of elite swimmers (whose main physical activity, although as aero-

bically strenuous, does not involve bearing weight).Lower bone densities become particularly evident in ageing females, for

whom osteoporosis is a problem. Low-level resistance weight training forwomen in these older age groups has proven to help reduce the chances andseverity of osteoporosis.

These findings do not suggest that all resistance training is beneficial.Overtraining (see chapters 9 and 10 in Live It Up 2, second edition) can resultin bone damage — for example, stress fractures in distance runners’ feet, orin the limbs of footballers who have excessive training regimes. Growing

bones may also suffer when a person lifts heavy weights in low repetitions,which can be especially traumatic to the epiphyseal plates.

Figure 5.9:

Low-level resistance

weig ht trainin g can delayor lessen osteo porosis.









contractions

Key skills• Use correct terminology to




• Observe and record how

the body systems function

during physical activity.

Report on participation in physical activity

Primary school activity patterns

List the exercise-based activities in which you participatedduring primary school and now at high school.1. What were the reasons for your activities at primary school?2. Who decided what you played or participated in?

3. What role did these activities play in your bone developmentand bone growth?4. As a high school student, do you exercise enough to promote

your bone growth and bone development?5. Explain how you would change someone’s exercise routine

if their present habits were sedentary.6. In class discussion, assess your attitude towards, and knowledge

of, the correct ways to participate in safe weight trainingfor bone and muscle development in adolescents.

Activity 4




Types of jointThe skeleton has three major joint types. Synovial joints offer a range ofmovement while immoveable joints (such as in the skull, pelvis, sacrum andsternum) offer no movement, and slightly moveable joints (such as in thevertebrae and where the ribs join the sternum) are joined by cartilage andallow small movements.

Synovial jointsThese freely moveable joints are of most interest to physical education

because they are directly involved in producing skilled movement. They areclassified by a number of qualities:• free movement in at least one direction• cartilage that offers protection and cushioning• ligaments that secure bones in place and allow

controlled ranges of movement• enclosure by a joint capsule (a layer of tissue that surrounds

the joint and holds it together)• a synovial membrane that lines the inside of the joint capsule

and secretes synovial fluid which promotes lubricated

movement by the joint.The knee joint is perhaps the most publicised of the synovial joints, given

its propensity for collapsing during football or netball matches.However, theknee joint is actually more stable than the shoulder joint. Strong ligamentssecuring the knee joint restrict its range of movement, whereas the shoulder

joint has a less restrictive ligament structure as well as a relatively shallow ball-and-socket joint framework (figure 5.12). Thus the shoulder has muchgreater mobility than does the knee, but with much less stability and ahigher likelihood of dislocation.

Figure 5.12:

T he shoulder and knee joints are t wo of the most commonly reco g nised

of the synovial joints , but their anatomy means they have di fferent qualit ies

in mobility and stability.

Figure 5.10:

I mmoveable fibrous joints form

the skull.

Figure 5.11:

Slig htly moveable ( cart ila g enous )

joints in the s pine

Fixed joint

Cartilage disc

Vertebr

a

Shoulder joint Coracoid process

Acromionprocess

Articular capsule

Glenohumeral

ligaments

Scapula

Tendon of biceps brachii muscle

Coracohumeral

ligament

Anatomical neck

Greater

tubercle

Lessertubercle

Humerus

Posterior ligaments ofthe right knee joint

Posteriorcruciateligament

Anteriorcruciateligament

Medial meniscus

Patellarligament (cut)

Medial collateral ligament

Tibia

Femur

Lateral collateral

ligament

Lateral

meniscus

Fibula











contractions




undertaking physical exercise.

• Perform, observe, analyse,

evaluate and report on

laboratory exercises related

to the body systems.

Laboratory report

Dissection of lamb shank

In a laboratory and with a partner, dissect a lamb shank,recognising each of the following: • freedom of movement before ligaments are cut• cartilage• ligaments• origins• insertions• cancellous bone• compact bone• bone cavity• bone marrow• the site of the epiphyseal plate.(All these terms are described throughout this chapter and/orin the glossary.) Write a short report on your findings.

Activity 5

Figure 5.13:

T here are many terms for s peci fic skeletal movements in var ious act ivit ies.

Flexion

Extension

Lateral flexion Rotation Forward

rotation

Backward

rotation

Elevation Depression

Flexion

Extension

AdductionAbduction Extension

Dorsiflexion

Plantarflexion

External rotation Internal rotation

Flexion

Flexion Abduction AdductionExtension

Inversion Eversion





movement terminology,

major joints and joint action,

major muscles, characteristics

and functions of skeletal

muscle fibre types,

nervous control of muscles,

the mechanics of breathing,

types of muscular

contractions.

Multimedia presentation

Interesting facts search

Read the article in figure 5.14 and carry out the following activities.1. Use an Internet search engine to find some websites that give

similar interesting facts on the human body.2. Create a three-slide PowerPoint presentation that shows some

amazing facts about the skeletal system that you have just studiedwhile also providing some tantalising facts about the muscularsystem that you are about to study.

Activity 6

1. More power!Looking for an innovative wayto save on power bills this winter? The human body is an efficient powersource and the idea of harvesting itsenergy is a rapidly growing field ofresearch. According to NASA, thehuman body is, on average, 15 percent fat and capable of producing11 000-watt hours of power. Somewatchmaking companies are alreadyin on the act, producing timepieces

that are powered by a weight thatswings with the movement of thewearer, and in turn powers a tinygenerator. Next time the lights goout, keep in mind that your brainis capable of powering a 10-wattlight globe.

2. Navel gazingTime to contemplate the navel.The bellybutton is actually yourfirst scar, left from the severing ofthe umbilical cord at birth. To settlethe ‘innie’ versus ‘outie’ debate onceand for all, the general consensusis that a concave navel is orthodox,

belonging to 90 per cent of people.A protruding bellybutton resultsfrom scar tissue and unusual medicalpractice. The substance that builds uparound the navel is called bellybuttonlint and is mostly made up ofclothing fibres and dead skin flakes.According to a survey conducted byDr Karl Kruszelnicki, lint is morelikely to appear in the concave

bellybuttons of old, hairy men.

3. Speed livesThe various functions of the human

body can produce great bursts ofenergy, none more so than nervemessages that speed around the bodyat approximately 384 kilometres an

hour. A distant second in the speedstakes are nasal fluids, which aresneezed out of the body at closeto 160 kmh. The bursts of air thatcome out of the mouth as a cough,languish behind, clocking up a morecautious 96 kmh.

4. Dealing with lossDespite its many endearing qualities,the human body is one of the biggestlosers known to man. Humans shedaround 400 000 skin particles every

hour, which pales in comparisonto the 300 000,000 cells lost everyminute. Babies are born with 300

bones— however, by adulthood,94 of those have been connected toothers, leaving only 206. Of moreimmediate concern, the averageperson releases almost 600 millilitresof intestinal gas by flatulence everyday, most of which is caused by theswallowing of air and the fermen-tation of undigested food. Statisticson what percentage of said gas isreleased in elevators was unavailableat the time of going to print.

5. ChemistryThe human body is like amobile chemistry lab, with complexreactions taking place all the time.Resource companies, tired of scouringthe outback for rich deposits, may

be interested to learn that insideour own bodies we have copper,zinc, cobalt, calcium, manganese,phosphates, nickel and silicon.Most chemicals in the body areproduced by the liver, which is

like the body’s chemical factory.The liver is also responsible forproducing enzymes, which act likedoormen, quickly escorting chemicals(such as recreational drugs) out ofthe body at the first sign of trouble.

Peter Kerr

The Knowledge

Five things you should know about …

The human body

Figure 5.14

Source:

T he Ag e , 18 April 2002.



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Muscular system

FunctionsThe human body has over 600 muscles. These muscles function to allow arange of physical movements that we either consciously or subconsciouslycontrol. These movements range from fine motor skills such as blinking an

eye or writing, to gross body movements such as sprinting or throwing a ball (see chapters 1 and 3 for more information on skilled movement). The body’s health relies on essential subconscious movements that need muscleeffort; for example, the diaphragm and intercostal muscles help breathing,while muscular contractions around the digestive tracts enable nutrientintake to be converted for body use.

Body movement

All muscles that we can consciously control (voluntary muscles) are attachedto bones. The central nervous system sends a message to the relevantmuscle, then the muscle(s) pull the bones to allow the desired movement(see ‘Origins and insertions’, page 177 ).

Figure 5.15:

Skeletal muscles , from the

front and back of the body

Pectoralis ma jorbrings arm to sideand across chest.

Bicepsbrachii

flexeselbow.

Flexors

flex wrist and fingers.

Abdominalsprotect vital organs,

maintain

good postureand flex hips.

Extensorsturn foot and toes upwards(dorsiflexion)

Deltoid

Quadriceps

flex hip- joint

and extend

knee.

Inner and outer thigh

Deltoid raises arm. Latissimus dorsi

draws arm backwardsand turns it inwards. (It also drawsdownwards anupstretched arm.)

Trapezius raisesshoulder and pulls head back.

Rhomboids

(under

trapezius)

Extensorsextend wrist

and fingers.

Lower back and waist

Gluteals extend hip- joint

and move leg outwards.

Gastrocnemius flexes kneeand turns foot downwards

(plantar flexion).

Hamstrings flex knee and extend hip joint.

Achilles

tendonFlexors turn foot and

toes downwards

(plantar flexion).

Tricepsbracchiextendselbow.



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Adequate posture

Muscles are continually in a state of ‘tone’ that affects their ability to helpour body to maintain an upright posture when awake and to function safelyduring sleep. People with poor muscle tone generally have poor postureand resultant aches and pains because gravity is defeating the muscles’resistance. Muscles of the upper back — such as the trapezius, rhomboidsand the latissimus dorsi — particularly influence posture maintenance.

Regular exercise helps improve muscle tone, which allows resting musclesto resist being stretched and keeps them in constant readiness.

Essential bodily functions

The involuntary muscles, over which we have little or no conscious control,function continuously and preserve our ongoing body needs whether weare awake or not. The heart is a muscle over which we generally havelittle control, and muscular effort also controls our digestive and breathingdemands.

Types of muscle• Skeletal muscles are often called striated muscles,

given their microscopic striped appearance (figure 5.16).These muscles are responsible for all voluntary movementsand are toned by fitness programs. They determine postureand are further examined on page 172.

• Smooth muscles are found in the digestive system and thewalls of other vital organs such as the bladder and blood vessels.These muscles are classed as involuntary because a person hasno conscious control over their movements.

Figure 5.17:

Smooth muscle contracts

rhythmically and wor ks

without conscious effort.

Figure 5.18:

C ardiac muscle is a combinat ion

of the other t wo muscle ty pes.

Figure 5.16:

Skeletal muscle

• Cardiac muscle is the muscle of the heart. It has a striated appearance but is also involuntary, so it has a mix of the qualities of the othertwo types of muscle. This is an extremely effective combination for itsdemanding and vital role in a person’s health and wellbeing.

CHAPTER 5 MUSCULOSKELETAL SYSTEM



Connective tissueConnective tissue plays an important role in the function of both the skeletaland muscular systems. It is classed as soft tissue (particularly in sportsinjuries; see chapter 10, Live It Up 2, second edition) because it does not havethe rigidity of bone whereas it does have the flexibility of soft tissue alongwith the strength that collagen provides.

Cartilage

This smooth, slightly elastic tissue is found in various forms within the body: hyaline cartilage coats the ends of the bones in synovial joints ; discsof cartilage separate the vertebrae of the spine; the ribs attach to the sternumvia cartilage; and the hard part of the ear and the tip of the nose are alsocartilage.

Tendons

Tendons attach muscle to bones. They are inelastic and very strong, allowingmovement by helping muscles pull through the joint and on the bones. The

biceps muscle (figure 5.19) is an example of a muscle that works through two joints; it has two tendonous origins at the scapular (allowing the humerus to

flex away from the body) and the tendonous insertion into the radius in theforearm allows the forearm to flex upwards towards the humerus.

Ligaments

Ligaments cross over joints, joining bone to bone. Their slight elasticityallows small movement from the bones of the joint. Their main functionis to provide stability at the joint, preventing dislocation. If ligaments areseriously damaged in an accident, they may not be able to repair themselvesand may require surgery.

Skeletal muscleSkeletal muscles create movement by pulling on the bones to which they are

attached. Muscles can only pull not push, so they need to work in pairs toproduce movement. When the biceps muscle pulls upwards on the forearm,for example, the triceps needs to relax or stretch to allow the movement tooccur. Similarly, when the quadriceps muscle contracts to kick a football orto push from the ground when acceleration is required during a team game,the hamstrings muscle group must relax or stretch. The movement of thearm or leg is called flexion.

This paired movement is called reciprocal inhibition. The muscle whichcreates the movement is called agonist or ‘prime mover’, while the musclewhich relaxes to allow the movement to occur passively is called theantagonist.

Figure 5.19:

T endons of the bice ps muscle

Figure 5.20:

Lig aments of the knee joint

( side and rear views )

Biceps

(short

head)

Biceps

(long

head)

Tendon

insertion

on radius

Tendon originates

at scapula.

Biceps

muscle

belly

Quadriceps

tendon

Joint capsule

Patella

Oblique poplitecligament

Fibular collateral ligament

Patella ligament

Posterior cruciate

ligament

Anterior cruciateligament

Tibial collateral ligament

Fibular collateral ligament







and functions of skeletal

muscle fibre types, nervous

control of muscles, themechanics of breathing types

of muscular contractions

• The cardiorespiratory system:

structure of the heart

and lungs, mechanics of

breathing, gaseous exchange,

blood vessels, blood flow

around the body at rest

and during exercise


describe the role of the bodysystems at rest and when


Data analysis

Heart rate investigation

Take your heart rate, following directions from the teacher.After one to five minutes of quiet contemplation,record your heart rate again.1. What was the percentage fall in the rate? 2. Who had the greatest percentage fall in your class? 3. What is an acute body response?4. Take your heart rate again after walking around the classroom

for a few minutes. Answer the above questions again, comparingthis new heart rate with your heart rate after five minutes rest.

Activity 7

Muscle fibre typesThere are two distinct types of muscle fibres within the body’s muscularsystem. They are known as fast twitch (or white) fibres, and slow twitch(or red) fibres.

Each is better suited to a different intensity of physical activity.The characteristics of each will be better understood with knowledge ofthe anaerobic and aerobic energy systems that will be studied in chapter 7.H

owever, at this stage of study, it is enough to appreciate the character-istics of each of these fibre types.

Figure 5.21:

F emale body builders develo p

their fast t witch muscle fibres

to a hig h de g ree.



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C haracter ist ics of fastand slow t witch fibres Characteristic

Fast twitch

(white fibres)

Slow twitch

(red fibres)

1. Size Bigger Smaller

2. Force available Maximal Low

3. Oxygen supply L

imited P

lentiful 4. Nerve supply Plentiful Sparse

5. Speed of contraction Fast Slow

6. Genetic inheritance High High

7. Fatiguability High Low

8. Blood supply Low High

9. Hypertrophy potential High Low

10. Ability to change from FT to ST,or vice versa

Nil Nil

11. Chances of one person having thesame fibre type throughoutMinimal Minimal

(These characteristics will be better understood af ter readin g cha pter 7.)

12. Stores of creatine phosphate High Low

13. Stores of glycogen High High

14. Mitochondrial density Low High

15. Capillary density Low High

16. Myoglobin stores Low High

17. Stores of fat Low High

Table 5.1

Figure 5.22:

Steve M one g hett i is a well-known elite endurance athlete who has a hig h percenta g e

of slow t witch fibres in his le g muscles.



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(a) (b)Figure 5.23:

F or fl e xion at the elbow ,

the bice ps contracts while

the tr ice ps stretches.

F

or e xtension at theelbow , the tr ice ps

contracts while the

bice ps stretches.

Figure 5.24:

C limbin g a ro pe:

( a ) the a g onist muscle on the way

u p is the bice ps performin g an

isotonic concentr ic contract ion ;

( b ) the a g onist on the way down is

also the bice ps , now performin g an

isotonic eccentr ic contract ion.

Triceps

Biceps

Flexion

Extension

CHAPTER 5 MUSCULOSKELETAL SYSTEM

Types of muscular contractionThere are three types of muscular contraction: isotonic, isometric andisokinetic.

Isotonic contractions

These contractions change the length of the muscle while creating a force. If

the muscle shortens, it is a concentric contraction; if the muscle lengthens, itis an eccentric contraction.

These contractions occur when climbing a rope, for example. The bodypulls itself up, leading the biceps to shorten, create the force and performan isotonic concentric contraction. When the body lowers under control,the biceps lengthens, creates the controlling force and performs an isotoniceccentric contraction.


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Isometric contractions

This type of muscularcontraction creates force, but the length of themuscle does not change.

The contractionproduces the mostamount of force ofany type of muscular contraction,and therefore causes the muscle to tire more quickly.Many sports rely onperformers using isometric contractions, for example, the rugby scrum,rock climbing, amateur wrestling holds, the position out on the trapeze insailing, and the grip on a playing stick or racquet.

Isokinetic contractionsThese contractions allow the performer to work at a constant angularvelocity against a weight or resistance that changes as the performer moves

through the working muscle’s possiblerange of movement.

These contractions are only possiblewith the use of expensive, specialisedequipment, as sold under such brandnames as Biodex, Cybex, Kincom andHydragym. Muscles are stronger orweaker depending on their degree offlexion around the central joint (see

chapter 5, Live It Up 2, second editionfor further information). Isokineticequipment is able to accommodate

these differences and allow themuscle to work maximally at all

degrees of flexion throughoutthe training movement.

Figure 5.26:

T he quadr ice ps muscle g rou p can be both assessed and trained throu g h

its full ran g e of mot ion on a Biode x machine.

Figure 5.25:

I sometr ic

muscle

contract ions

are im portantto many s ports.




T he or igins , insert ionsand act ions of the ma jormuscles

Muscles that act on the leg

Muscle Origin(s) Insertion Action(s)

Lower leg• Tibialis anterior• Gastrocnemius

• Soleus

TibiaFemur

TibiaFibula

TarsalsTarsals

Tarsals

Dorsi flexionPlantar flexionKnee flexionPlantar flexion

Quadriceps• Rectus femoris• Vastus intermedius• Vastus lateralis• Vastus medialis

PelvisFemurFemurFemur

TibiaTibiaTibiaTibia

Hip flexionKnee extensionKnee extensionKnee extension

Hamstrings• Biceps femoris

• Semitendinosus

• Semimembranosus

PelvisFemurPelvis

Pelvis

Fibula

Tibia

Tibia

Hip extensionKnee flexionHip extensionKnee flexionHip extensionKnee flexion

Hip• Adductors•

G

luteals

• Sartorius

• Iliopsoas

PelvisP

elvis

Pelvis

Lumbar vertebrae

Femur

Femur

Tibia

Femur

Hip adductionH

ip extensionHip abductionHip flexionKnee flexionFemur rotationHip flexion

Muscles that act on the arm


Upper arm• Biceps brachii

• Brachialis• Brachioradialis• Triceps brachii

Scapula

HumerusHumerusScapulaHumerus

Radius

UlnaRadiusUlna

Elbow flexionShoulder flexionElbow flexion

Elbow flexionElbow extensionShoulder extension

Muscles that act on the wrist


Wrist flexorsWrist extensors

HumerusHumerus

MetacarpalsMetacarpals

Wrist flexionWrist flexion

Table 5.2

Origins and insertionsKnowing where the muscular tendons attach to bones is helpful in under-standing a muscle’s action. Figure 5.23, which illustrates how a muscle bodymoves into the tendon attachment, also shows the origins of the biceps aswell as its insertion. A muscle’s origin is the attachment that is closer (orproximal) to the body’s midline, while the insertion is further (or distal) tothe body’s midline. The insertion is usually attached to the bone that moves

most when the muscle contracts.

cont inued







and functions of skeletalmuscle fibre types, nervous

control of muscles, the

mechanics of breathing,

types of muscular contractions





Test

Muscle insertion and origin knowledge

Ask your teacher to photocopy table 5.2— one copyfor every two students.• Cut up each column, then cut out each term and place into

four piles: muscle, origin, insertion and action.• Mix up the terms in each pile.• With a partner, place the terms back in the correct columns,

trying this exercise without checking your text book.• Paste the terms into your workbook in columns, in the correct order.

Activity 8

Table 5.2 cont inued

Muscles that act on the shoulder


Shoulder• Pectoralis major

• Deltoids

• Latissimus dorsi

• Teres major

ClavicleS

ternum

Scapula

Lumbar vertebraePelvisScapula

HumerusR

ibs

Humerus

Humerus

Humerus

Shoulder flexionH

oriz

ontal shoulderflexionDiagonal flexionShoulder abductionShoulder flexionShoulder extensionShoulder adduction Shoulder extensionShoulder adductionShoulder extension


Muscle Origin(s) Insertion Action(s)Shoulder girdle• Pectoralis minor• Serratus anterior

• Trapezius

• Rhomboids

RibsRibs

Vertebral columnVertebral column

ScapulaScapula

Scapula

Scapula

Scapula depressionScapula abductionOutward rotationScapula elevationOutward rotationScapula adductionInward rotation



Rectus abdominis

Obliques

Erector spinae

Pelvis

Pelvis

PelvisSacrum

RibsSternumRibs

Base of skullRibs

Trunk flexion

Trunk rotationTrunk flexionTrunk rotationTrunk extension




Brain

Motor unit

Neuromuscular

junction

Motor neurons

Motor nerve

Spinal cord

1

2

3

44 4

4 4




major muscles, characteris-

tics and functions of skeletal

muscle fibre types, nervous

control of muscles, the

mechanics of breathing,

types of muscular contractions





• Observe and record how the

body systems function during

physical activity.

• Identify and discuss the range

of acute effects that physical

activity has on the body.

Written report

Action muscles in sport

Select a sport or recreational activity of your choice.1. List four different body movements used in the activity.2. Sketch each movement. These may be your best art work

or simple but clear stick figures. Use one A4 page for each drawing.3. Clearly indicate the agonist muscles and the antagonist muscles

for each movement.

Activity 9

Figure 5.27:

N er vous control of muscular movement 4

Stages of nervous control

of muscle action

1 Brain initiates message.

2 Nervous impulse branches

from spinal cord to motor nerve.

3 Message passes into

motor neurons.

4 Message branches off

to arrive at all muscle fibres

controlled by that nerve;

travels across gap at

neuromuscular junction

(aided by acetylcholine)

and all connected muscle

fibres contract.

Nervous control of musclesTo enable conscious control of muscles, the brain must send electricalnervous messages to the muscle. These messages or signals travel down

the spinal cord to the motor nerves which branch fromthe spinal cord to the relevant muscles. Leaving

the spinal cord, the motor nerve separates intosmaller motor neurons which then divide

a number of times to attach to individualmuscle fibres. Where the nerves meet themuscle fibres, there is a gap (called aneuromuscular junction or, the synapticcleft) across which the nerve impulsehas to travel. A ‘neuro-transmitter’,which is a chemical compound calledactetylcholine, helps the nerve impulsemake this jump. The muscle willcontinue to contract for as long as the

brain sends messages and the relevantenergy sources last (figure 5.27).

One motor neuron and the fibres thatit controls form a ‘motor unit’. When anelectrical nerve impulse tells the fibres to

contract, all the fibres linked to this nervecontract totally. This is known as the ‘all ornone’ law and is further explained in chapter 5in Live It Up 2, second edition. So when you lift adrink to your mouth, your brain tells far fewermotor units to contract than when you attempta heavy biceps curl during weight training.




Acute responses of the muscular systemAcute muscular system responses to exercise are those that occur within theworking muscles themselves. These responses vary according to the type,intensity and duration of the exercise performed, and may differ accordingto the type of muscle fibre recruited (fast-twitch as opposed to slow-twitch fibres). However, these responses basically include:• increased motor unit and muscle-fibre recruitment• increased blood flow to the muscles• increased muscle temperature• increased oxygen supply and utilisation• depletion of muscle energy stores.

Increased motor-unit and muscle-fibre recruitment

Any physical activity creates a need for muscular contractions. When exercise begins, motor unit recruitment must increase so that more muscle fibresare activated to contract. The greater the force or effort required, the greaterthe number of motor units recruited and the greater the number of musclefibres activated.

Increased blood flow to the musclesAs the muscles demand extra oxygen during exercise, this leads to vasodi-lation of the capillaries and redistribution of blood flow from the internalorgans to the working skeletal muscles.

Increased muscle temperature

Increased blood flow to the muscles coupled with the heat generated as a by-product of the increased production of adenosine triosophate (ATP, seechapter 7) during exercise, results in an increase in muscle temperature.

Increased oxygen supply and utilisation

The muscle cells attract and utilise more oxygen during exercise because of

the increased demand for ATP.

Depletion of muscle energy stores (ATP-PC, glycogen and triglycerides)

Muscular sources of fuel for the production of ATP begin to deplete duringexercise.


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C H A P T E

R R E V I S I O N

182LIVE IT UP 1

Review questions

1. Define in your own words the key terms listed below, all of whichappear in this chapter. When you have finished, check your definitionswith those in the glossary on page 285:

bone densitycalcium

cancellous bonecardiac musclecartilagecollagencompact bonediaphysisdiaphragmepiphyseal platesflat bonesflexionhaemoglobinintercostal musclesirregular bonesisokineticisometricisotonic

joint capsuleligament

long bonesmuscle fibresmuscle functionsmuscle origins and insertionsnervous control of musclesosteoporosisred blood cellssesamoid bonesshort bonessmooth musclessynovial jointstendonstypes of bonevertebraevitamins A, C and D

2. Discuss the five main functions of the skeletal system. 3. List the five types of bones in the skeletal system

and give one example of each. 4. After studying aspects of the spinal column,

(a) list the four main sections of the spine(b) how many vertebrae are in each section?(c) describe how the vertebrae change along

the length of the spine(d) provide some possible reasons for this change

(e) list the main functions of the spine(f) which major muscle groups surround the spine?(g) discuss some effects that these muscle groups

exert on the spine. 5. What are the main vitamins that affect the health

of the skeletal system? 6. Name the main dietary sources of these vitamins. 7. What role does exercise play in skeletal health during your life? 8. Examine the knee and elbow joints. Explain the major differences

between the two and how these may relate to sporting injuries. 9. Test a partner on his or her knowledge of movement terminology. 10. Test a partner on his or her knowledge of the major muscle groups

in the body. 11. Examine the main functions of the muscular system. 12. Name and describe the three types of muscle. 13. Consider these sports and decide, with reasons,

which of fast twitch, slow twitch fibres or a combinationof both would be more important in them:– weight-lifting – athletics, long jumper– Tour de France – athletics, decathlete– soccer goal-keeping – tennis– hockey, inside right – sprint cycling– netball, wing attack – basketball, centre– AFL, centre half forward – water polo.

http://../technology/crosswords/chapter5.htahttp://../technology/review-questions/chap-05.doc


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14. Name the agonist and the antagonist musclein each of these movements.(a) a pushup(b) a chinup with hands facing towards you(c) a chinup with hands facing away from you(d) a biceps curl in weight training(e) a bench press in weight training

(f) a leg extension in weight training(g) an upright row in weight training(h) a half squat in weight training(i) accelerating from the blocks in an athletic sprint(j) the full rowing movement when rowing(k) a forehand in tennis(l) shooting for goal in netball(m) a hockey penalty stroke(n) moving from standing to sitting(o) throwing a cricket ball from the boundary to the ‘keeper’.

15. Using the same movements described in question 14, decidewhat type of muscular contraction is being performed in each.

16. Name the stages passed by a nervous impulse as it moves

from the brain to a muscle site to initiate a movement. 17. Outline the ways the muscular system can respond

to one session of physical activity.

Usef ul websites

Major muscle groups and microscopic structure—www.anatomy.usyd.edu.au / mru / lectures

Muscle biochemistry—web.indstate.edu / thcme / mwking / muscle.html

Muscle physiology homepage—www.muscle.ucsd.edu / musintro / struct.html

Muscle structure

—

www.rrcc.cccoes.edu / academic / health / fitnesscenter / muscle.htm

Muscle structure and function—members.tripod.com / Dramo13 / Muscles / structure.html

www.naturalstrength.com

Muscles—www.e-muscles.net

www.innerbody.com

NewMexico State performance training handbook—web.nmsu.edu / ~johtaylo / index.html

www.exploratorium.edu / sports / sports_faq.html

Documents

sport and recreation PDF