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Body in Action – Muscular System Roughly 40% of your body mass is made up of muscle, the key purpose of which is to move the bones of your body. In this assignment muscle movements and short and long term responses to exercise will be looked at. Types of Muscle Within the body, there are three different types of muscle. 1. Cardiac Muscle 2. Skeletal Muscle 3. Smooth Muscle Cardiac Muscle This is specialised muscle of the heart (BTEC National Sport Book 1). This is an involuntary type of muscle and is continuously working within the walls of the heart.
This muscle does not tire quickly and each contraction along with a relaxation can be called a heartbeat. Skeletal Muscle Skeletal muscle is a type of striated muscle, usually attached to the skeleton. Skeletal muscles are used to create movement, by applying force to bones and joints; via contraction. (http://en. wikipedia. org/wiki/Skeletal_muscle) Unlike cardiac muscle, skeletal muscle is voluntary and can sometimes be known as voluntary muscle. Smooth Muscle Smooth muscle can also be known as involuntary muscle. These muscles are functioned by the nervous system and are contracted without thought.
These muscles can be found in the digestive system. Fibre Types All skeletal muscle contains a mixture of fast and slow twitch fibres. Slow-twitch fibres contract slowly and can be used for longer periods of time. Fast-twitch fibres contract quickly and provide strength and speed, though they also tire more quickly. To a large extent this fibre combination is hereditary, so if you want to become the next gold medal winner at the Olympics it is dependant on your parents. The duration and intensity of your activity will influence the physiology of your muscle tissue and the development of your muscle fibres.
Endurance athletes tend to develop a greater percentage of slow-twitch muscle fibres, while power athletes tend to develop a greater percentage of fast-twitch muscle fibres. (http://www. bodyandfitness. com/Information/Training/twitch. htm) Slow twitch fibres are known as type 1 and fast twitch known as type 2. Type 1 These fibres have very strong aerobic ability for oxidation, they contract very slowly, and they are very useful in endurance activities. They do not tire quickly and have high levels of mitochondria to produce high levels of energy. These are needed in endurance sports such as skiing and cycling.
Type 2a These are fast-oxidative fibres. These have the stored glycogen and enzymatic properties of FG fibres, in addition to high levels of oxidative enzymes, which assist aerobic metabolism. They have the best of both worlds. (http://www. bodybuilding. com/fun/drobson33. htm) These fibres are used in middle-distance sports, including the 400 and 800m. Type 2b These are known as fast glycolytic fibres. They contain low myoglobin content and few blood capillaries. These are needed for quick sports, which take little time, such as the 100m sprints. Characteristics of muscle tissue
Fibre TypeType 1 fibresType 2a fibresType 2b fibres Contraction timeSlowFastVery fast Size of motor neuronSmallLargeVery large Resistance to fatigueHighIntermediateLow Activity used forAerobicLong term anaerobicShort term anaerobic Force productionLowHighVery high Mitochondrial densityHighHighLow Capillary densityHighIntermediateLow Oxidative capacityHigh HighLow Glycolytic capacityLowHighHigh Major storage fuelTriglyceridesCP, glycogenCP, glycogen Major Muscles It would be unattainable for you to do anything without your muscles. Absolutely everything that you visualize with your brain is spoken as muscular motion.
The only ways for you to express an idea are with the muscles of your larynx, mouth and tongue, with the muscles of your fingers or with the skeletal muscles. As there are more than 640 muscles in the human body, it would be difficult to remember them all and their different functions, in the sporting world we learn and remember the main muscles. These are listed below according to BTEC National Sport Book 1. Muscles in the shoulder: •Levator scapulae – Raises shoulder blade •Pectoralis minor – Lowers shoulder blade •Trapezius – Lifts clavicle. Adducts, elevates and rotates scapular outwards. Rhomboideus major – Adducts scapular and rotates it inwards •Serratus anterior – Stabilises scapula when hand exerts pressure on an object Muscles in the arm: •Pectoralis major – Flexes, adducts and rotates arm medially •Latissimus dorsi – Extends, adducts and rotates arm medially. Moves arm downward and backwards •Deltoid – Abducts, flexes, extends and medially and laterally rotates arm •Teres major – Extends arm, assists in adduction and medial rotation of arm Muscles in the forearm: •Biceps brachii – Flexes and supinates forearm. Flexes arm •Brachialis – Flexes the forearm Brachoradialis – Flexes, semi-supinates and semi-pronates the forearm •Triceps brachii – Extends forearm. Extends arm •Pronator teres – Pronates and flexes forearm •Pronator quadratus – Pronates the forearm and hand •Supinator – Supinates forearm and hand Muscles in the abdomen: •Rectus abdominis – Compresses abdomen and flexes vertebral column •External obliques – Bends vertebral column laterally and rotates vertebral column •Transversus abdominis – Compresses abdomen •Quadratus lumborum – Side flexion Muscles in the back: •Iliocostalis lumborum – Extends lumbar region Iliocostalis thoracis – Maintains the spine’s erect position •Iliocostalis cervicis – Extends cervical region •Longissimus thoracis – Extends thoracis region •Longissimus cervicis – Extends cervical region •Longissimus capitis – Extends the head and rotates it to opposite side •Spinalis thoracis – Extends vertebral column •Spinalis cervicis – Extends vertebral column •Spinalis capitis – Extends vertebral column Muscles in the leg/foot: •Psoas major – Flexes and rotates thigh medially and flexes vertebral column •Iliacus – Flexes and rotates thigh medially and flexes vertebral column Gluteus maximus – Extends and rotates thigh laterally. •Adductor longus – Adducts, medially rotates and flexes the thigh •Adductor brevis – Adducts, laterally rotates and flexes the thigh •Adductor magnus – Adducts, flexes, laterally rotates and extends the thigh. •Rectus femoris – Extends knee and flexes hip •Vastus lateralis – Extends knee •Vastus medialis – Extends knee •Vastus intermedius – Extends knee •Sartorius – Flexes knee. Flexes hip and rotates femur laterally •Biceps femoris – Flexes leg and extends thigh •Semitendinosus – Flexes leg and extends thigh Semimembranosus – Flexes leg and extends thigh •Tibialis anterior – Dorsiflexes and inverts foot •Peroneus tertius – Dorsiflexes and everts foot •Gastrocnemius – Plantar flexes foot and flexes knee •Soleus – Plantar flexes foot •Plantaris – Plantar flexes foot •Tibialis posterior – Plantar flexes and inverts the foot •Peroneus longus – Plantar flexes and everts the foot •Peroneus brevis – Plantar flexes and everts the foot (http://www. brianmac. co. uk/musclefun. htm) Muscle Movement To carry the body into movement, muscles must cross the joint they move.
Some cross more than one joint to produce movements in more than one place, for example the bicep crosses the elbow and shoulder joint causing flexion at both joints. Agonist Agonist is a kind of muscle that causes movement to occur. It creates the normal range of movement in a joint by contracting. Agonists are also referred to as “prime movers” since they are the muscles that are primarily responsible for generating movement. (http://en. wikipedia. org/wiki/Agonist_(muscle) During a bicep curl, the bicep is the agonist. Antagonist This is the muscle that works along side the agonist. As one relaxes the other contracts.
If the antagonist did not relax then the muscle itself could not carry out movement. During a bicep curl the tricep is the antagonist. Origin A muscles origin is attached to the immovable or less movable bone. As the tricep contracts the origin is at the humerus. Insertion A muscles insertion is attached to the movable bone. As the tricep contracts the insertion is at the ulna. Synergist Synergists are muscles that work together to enable the agonists to operate more effectively. They work with the agonists to control and direct movement by modifying or altering the direction of pull on the agonists to the most advantageous position. BTEC National Sport Book 1) Fixator These stop muscles moving in any unwanted direction. They can help maintain posture by stabilising the joints. Types of Contraction: Isometric This contraction is one in which the muscle is activated, but instead of being allowed to lengthen or shorten, it is held at a constant length. An example of an isometric contraction would be carrying an object in front of you. The weight of the object would be pulling downward, but your hands and arms would be opposing the motion with equal force going upwards.
Since your arms are neither raising nor lowering, your biceps will be isometrically contracting. (http://muscle. ucsd. edu/musintro/contractions. shtml) Concentric A concentric contraction occurs when a muscle is contracted against a type of force. Using a free weights machine in a gym can be a concentric contraction for the knee joint. Another way of hearing concentric contraction is the positive phase of muscle contraction. Eccentric This occurs when a muscle returns to its normal length after shortening against a resistance.
Using the bicep curl as an example, this is the controlled lowering of your arm to the starting position. (BTEC National Sport Book 1) Responses to Exercise Short term An increase in body temperature and an increase in metabolic activity can be classified as short-term effects of exercise on your muscles. • Muscle damage The warm up of your muscles during and before any activity makes them more flexible and reduces the risk of muscle damage and injury. Long term These effects depend upon how strenuous the activity and how often the sport was participated in for. • Hypertrophy
The strength and bulk of the muscles increase in response to a programme of a progressive resistance training. Flexibility training leads to an increased range of movement around your joints. The muscles need to be kept in continuous use for them to remain in good condition. (BTEC National Sport Book 1) • Increased strength of tendons Tendons are designed to resist tension. Tendons can adapt, depending on how often training takes place. Adaptations to different training programmes Different adaptations occur depending what training programme is used. • Aerobic Endurance More myoglobin created in the muscle cells o More and bigger mitochondria in the muscle cells o Increase in oxidative enzymes hence increase in energy production within muscle cells o Increase in stores and use of fat o Increase in stores of glycogen in the muscle enabling more fuel to be available for aerobic work o Conversion of type 2b to type 2a fibres o Endurance training increases the aerobic capacity of slow twitch fibres, explains why long steady training results in loss of speed. • Anaerobic fitness o High intensity anaerobic training causes increase in size of fast twitch ibres and number of fast twitch fibres. • Muscular strength o Muscle hypertrophy of fast twitch fibres o Increased number of myofibrils within each muscle cell o Increased sarcoplasmic volume o Increase in contractile proteins o Increase in mass of fast twitch fibres o Increased number of fast twitch fibres – percentage of type 2 increases and type 1 decreases o Improved ability to remove lactate from muscle cell into blood therefore enhancement of alactic and lactate. • Flexibility o A long term training response is to toughen up proprioceptors so that reflexive muscle action is delayed.
Conclusion In this assignment the muscular system is described in detail, including how short and long term effects can result from exercise. The structure and function is explained and each response described. Bibliography BTEC National Sport Book 1 http://en. wikipedia. org/wiki/Skeletal_muscle http://www. bodyandfitness. com/Information/Training/twitch. htm http://www. bodybuilding. com/fun/drobson33. htm http://www. brianmac. co. uk/musclefun. htm http://en. wikipedia. org/wiki/Agonist_(muscle) http://muscle. ucsd. edu/musintro/contractions. shtml