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Saturday, June 18, 2011

Anatomy of physical performance

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P.E � The Anatomy Of Physical Performance


The human skeleton has 06 bones. Many of these, in combination with over 600 skeletal muscles, enable the human body to achieve a variety of actions, such as running, throwing, striking, jumping, pulling and pushing.








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Joints are covered with compressible articular ( this is something that describes surfaces which move or hinge ), or hyaline cartilage, which cushions the impact of large forces on bone ends. Joint movements are varied. All skeletal bones and joints enable the body to carry out a vast range of complex movements demanded by a variety of differing physical and sporting situations.


The human skeleton has been created by evolution to perform the following functions


To provide a lever system against which muscles can pull.


To provide a large surface area for the attachment of muscles.


To protect delicate organs (E.g.; the cranium protects the brain).


To give shape to the body


To give support to the body (E.g.; the firm construction of the thorax, which permits breathing).


To manufacture red blood cells and to store fat, calcium, and phosphate.


Types Of Bones


The shape and size of bones are designed according to their specific functions. They can be long, short, flat, or irregular.


A Long Bone


A long bone consists of a hollow cylindrical shaft formed of compact bone located at the knobbly ends of the shaft.


The tibia is an example of long bone.


A Short Bone


A short bone consists of entirely cancellous bone surrounded by a thin layer of compact bone. The carpals in the wrist are examples of short bones.


Flat And Irregular Bones


Flat and irregular bones consist of two outer layers of compact bone with cancellous bone between them. The cranium is an example of a flat bone. Examples of irregular bones include the vertebrae, the patella or sasamoid bone and wormian bones, which are small irregular bones sometimes formed in cranial sutures.


Irregular bones have no definite shape. The vertebral column, which is part of the axial skeleton, is composed of 4 un-fused vertebrae � five fused sacral vertebrae attached to four fused coccygeal vertebrae, making a total of 6 bones.














Bone


Bone is classified as either hard or spongy. It is the hardest connective tissue in the human body and is composed of water, organic material and inorganic salts.


Compact Bone


Compact bone consists of thousands of collagen-based structures called Haversian Systems, which consist of a central canal, surrounded by a ring shaped, calcium-based plates called lamellae.


Spongy or Cancellous Bone


Spongy or cancellous bone has a honeycomb appearance and consists of a thin criss-cross matrix of bone tissue called trabeculae, with red bone marrow filling the tiny spaces.


Joints in Action


Keywords And Concepts


Joint Feature Movement Patterns Synovial Joints Cardinal Planes





Bursae Abduction Ball And Socket Frontal


Capsule Adduction Condyloid Sagittal


Cartiliginous Joint Circumduction Gliding Transverse


Fibrous Joint Depression Hinge


Ligaments Dorsiflecxion Pivot


Menisci Elevation Saddle


Pads Of Fat Extension


Synovial Joint External Rotation


Synovial Membrane Flexion


Internal Rotation


Plantar Flexion


Pronation


Supination


Types Of Joint


Fibrous or Fixed Joint


A fibrous or fixed joint has no movement at all. Tough fibrous tissue lies between the ends of the bone, which are dovetailed together. Examples in the human body are the sutures in the skull.


Cartilaginous Joint


A cartilaginous joint allows some slight movement. Pads of white fibro cartilage separate the ends of the bones, which are covered in articular or hyaline cartilage, and slight movement is made possible only because the pads of cartilage compress. In addition, the pads of cartilage act as shock absorbers. The inter vertebral discs are examples of this type of joint.


Synovial Joint


A synovial joint is a freely moving joint and is characterised by the presence of a joint capsule and cavity. This type of joint is sub-divided according to the movement possibilities, which are dictated as a result of the bony surfaces that actually form the joint.


Muscles in Action


Keywords And Concepts


Agonist Fibre types Fusiform Pennate


Antagonist Type 1 Insertion Periosteum


Antagonistic Lla (FOG) Ligaments Skeletal Muscle


Aponeuroses LLB (FTG) Muscle Group Synergist


Fascia Fixator Origin Tendon





One of the important functions of the human skeleton is to enable movement. Physical activity is achieved as the result of the action of over 600 muscles that contract or shorten, thereby facilitating the movement of the skeleton across its joints.


Muscles are the converters of energy, since they change chemical energy into mechanical energy. This is achieved as a result of the contraction of hundreds of muscles fibres within the connective tissue of each muscle. During muscular contractions a muscle tightens to produce a state of tension that is adequate to meet the demands of the activity. The effect of regular physical activity is to develop and sustain local muscle strength and endurance. Some skeletal muscles, for example, the soleus muscle, are very fatigue resistant, while other muscles, for example, the biceps and gastrocnemius muscles, fatigue more quickly as they are essentially fast twitch. However, all muscles will contract only when stimulated by nerve impulses.


Shapes Of Muscles


Skeletal muscles vary in shape and function. Each muscle shape, its origins, insertion and positioning, has evolved specifically to deal with its unique functioning.


Fusiform


Fusiform means spindle-shaped, since the muscle fibres run the length of the muscle belly to converge at each end. This strap-like, round shape enables the muscle to perform a large range of movement fluidity.


Pennate


Pennate means featherlike. A pennate muscle is a flat muscle in which fibres are arranged around a central tendon, like barbs of a feather.


The major types of pinnate muscles are grouped according to the way in which the fibres are arranged around a central tendon.








Types of Muscle Fibre


Muscle tissue is composed of muscle fibres that contain two main fibre types, which contract at different speeds namely, fast twitch fibres and slow twitch fibres.


Within an individual there are different proportions of these fibre types to be found in different muscles, and evidence supports the view that fibre type distribution is inherited.


All muscle contains a mixture of slow and fast twitch fibres. The major differences between the two types are related to


1. Speed of contraction � slow twitch muscle fibres contract at a rate of about 0% when compared with fast twitch muscle fibres.


. Muscle fibre force � fast twitch fibres are bigger in size than slow twitch fibres, have larger motor neurons and therefore can generate high force rapidly


. Muscle endurance � slow twitch fibres are capable of resisting fatigue, whereas fast twitch fibres are easily fatigued.


More recently, it has been discovered that type II fibres (fast twitch) are subdivided into type IIa and type IIb. Type IIa fibres, otherwise known as FOG (Fast twitch high Oxidative Glycolytic), have a greater resistance to fatigue, compared with type IIb (Fast Twitch Glycolytic � FTG). The fatigue resistant nature of type IIa is entirely due to muscle adaptation in response to endurance training.


How Skeletal Muscle Works


Muscles and bones have specialised skeletal structures, such as tendons and the periosteum of a bone which generally transmit muscular forces to bones or, in the case of ligaments, attach bone to bone. These structures are commonly known as musculo-skeletal attachments.


Tendons


Muscles are attached to bones by tendons, which pass over joints. Tendons are strong and inelastic, and vary in length and structure from one to another. Small tendons, such as those to the muscles that control eye movement, have no nerve and no blood supply; whereas large tendons such as the Achilles tendon, are connected to the central nervous system and the circulatory system, and therefore have nerves and a blood supply both of which are substantially less prolific and effective than in the actual muscles. In some cases, the tendinous attachment to bone is a more flattened or ribbon shaped connection, called an aponeurosis. This type of tendon is without nerves. An example is the aponeurosis of the internal oblique muscles. Tendons are rigidly cemented to the periosteum.


Where the tendon fastens onto the periosteum, structures called Sharpy’s fibres firmly attach tendon tissue onto periosteal tissue


The periosteum is tough connective tissue, who’s function is to attach muscle tendons to bone, and to assist bone growth.





Other Connective Tissue


Fascia is a general form of connective tissue that overlays or underlines many body structures. A specialist example of this is the epimysium, which the name for the sheath or membrane that envelopes muscle systems.


Superficial fascia underlines the skin and forms the connective link between the skin and deep fascia of muscle.


The Origin and Insertion of Muscles


The tendon at the static end of the muscle is called the origin, and the tendon closest to the muscle at the end of the joint that moves is called the insertion of the muscle.


The Arrangement of Muscles


Muscles that cause joints to bend are called flexors, while those muscle that straighten a joint are called extensors.


Skeletal muscles are normally arranged in pairs, so that as one muscle is contracting the other is relaxing, thus producing co-ordinated movement.


The muscle that actually shortens to move the joint is called the prime mover, or agonist, whereas the muscle that relaxes in opposition to the agonist is called the antagonist. Muscles that are prime movers for one movement act as antagonists for the opposite movement. For example, the biceps (agonist) contracts while the triceps (antagonist) relaxes. This combined action causes the elbow to flex. When the elbow straightens the reverse occurs the triceps contracts, while the biceps relaxes. The action of muscles working in pairs is called antagonistic muscle action. Antagonistic muscle action limits and controls movements, especially when there are groups of muscles acting together.


In addition, there are muscles that stabilise the origin to the prime mover so that only the bone into which it is inserted will move. These are called fixators and synagists. Fixator muscles hold joints in position and are sited so that the origin and insertion are on opposite sides of a stabilized joint. Synergists are muscles that hold body position to enable the agonist to operate. Note that the terms “fixator” and “synergist” can be applied to the same muscle.








Types Of Muscular Contraction


Keywords And Concepts


Ballistic Isokenetic Mc Muscular Contraction


Concentric Isometric Muscle Plyometrics


Dynamic Contraction (Mc) Static


Eccentric Isotonic Mc


Muscular contractions can vary in speed, force and duration. For example, in cycling the action is cyclical and rhythmical, involving the interplay of agonist and antagonist, whereas the action of a boxer throwing a punch is ballistic in nature, since the arm is moved fluidly by a short, fast contraction of the agonist, and the movement is stopped as a result of the antagonist brake action.


During muscular contraction, a muscle may shorten, lengthen or stay the same. Where the muscle changes the length the contraction is classified as dynamic. When the muscle remains the same length, a static contraction occurs


Static Contractions � Isometric Muscle Contraction


Another name for static muscular contraction is an isometric contraction. This concept can be expressed as


Force of muscle = Force expressed


Contraction By Resistance


The result is that the muscle length and tension in the arm wrestling contest remain static. It is found that pushing or pulling without moving can produce a strength gain in the muscles used. In a training situation this is done by exerting the maximum possible force in a fixed position for sets of ten seconds, with a sixty second recovery interval. Its advantage is that a large amount of strength training can be done in a short time. Another advantage of isometric training is that it needs no special place or equipment and can be done at any time throughout the day. However, isometric training does little for cardiovascular fitness.


Concentric Contractions � Isotonic And Isokinetic Muscle Contraction


The sort of exercise in which muscles are used in a normal dynamic way and in which muscles contract at a speed controlled by the sportsman in whatever activity is being done called isotonic. In this case, the work is labelled concentric or positive because the resulting tension causes the muscle to create movement by shortening its length. The advantage of this type of exercise is that it stimulates real sporting use of the musculature. One of the adaptations produced by this type of training or exercise is to increase the capillarization of both skeletal and cardiac muscle and to enable these muscles to become more resistant to the onset of fatigue. Therefore it is most likely to lead to improvement in sporting performance.





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