Unit 1: The Body in Sport 2. Understanding the muscular system and how it is affected by exercise In this section you will learn how the skeletal and muscular systems are linked in the creation of movement during sports activities. You will also learn about the structure of joints and levers in the production of movement.

Classification of muscles All sports performers need to be able to move. Movement is possible through the use of muscles, but not all muscles bring about movement. There are three different types of muscle tissue that make up the muscular system. Can you name them?

The three different types of muscle tissue are: Cardiac muscle, which is only found in the heart. Smooth muscle, also known as involuntary muscle. Skeletal muscle, also known as voluntary muscle The structure and function of each of these muscle tissues are very different, and they are controlled by different methods

Cardiac Muscle This type of muscle is only found in the heart, and is a special form of involuntary muscle in that we have no direct conscious control over it. It also differs from voluntary muscle in that it does not tire, but continues to contract and relax throughout our lives.

Involuntary or Smooth Muscle Examples of this type of muscle can be found in parts of the digestive tract propelling food through the digestive system and the blood vessels that aid blood flow away from the heart to all parts of the body.

Skeletal or Voluntary Muscle This type of muscle is attached to the skeleton of the human body and is responsible for bringing about movement and maintaining body posture. These muscles are controlled by the central nervous system and we move these muscles with conscious thought.

Your body has over 600 muscles to enable it to move. You are going to concentrate on just 11. Can you name any muscles? Hamstrings Quadriceps Triceps Deltoid Latissimus dorsi Gastrocnemius Bicep Pectoral Gluteus maximus / Gluteals Trapezius Abdominals

Anterior View of the muscular system

Posterior view of the muscular system

Muscle and Sporting action Triceps - Extends lower arm at the elbow Volleyball player has arms outstretched to block the ball Biceps - Flexes arm at the elbow Tennis serve – racket preparation, when racket is behind head Deltoids - Abducts upper arm at the shoulder Preparation for a cartwheel in gymnastics Pectorals - Adduction of upper arm at the shoulder Arm action in front crawl (pull) Trapezius - Adducts and rotate scapula, rotation of head at atlas and axis Lifting of the head to watch the flight of the shuttle in badminton

Muscle and Sporting action Gluteals - Extends the leg at the hip Running action, one leg is left stretched back behind the other Quadriceps - Extends the leg at the knee Follow through after kicking a ball in football Hamstrings - Flexes the leg at the knee Taking the leg back in preparation to strike the ball in rugby Gastrocnemius - Plantar flexion of the foot Going up onto toes prior to take off in a diving competition Latissimus dorsi - Adducts and rotates the humerus at the shoulder Pulling the arm back in archery Abdominals - Flexes and rotates the trunk Forward action in sit ups

Structure and function of skeletal muscle Skeletal muscles are made up of many thousands of fibres. These in turn are made of even smaller fibres called myofibrils. It is within these smallest fibres that the contraction of the muscle takes place.

Muscle movement Skeletal muscle has a vast supply of nerve and blood vessels. Skeletal muscle is also termed voluntary muscle because movement is created via conscious thought process. Muscles pull to produce movement. In other words, the cells of the muscle tissue contract and then relax to their original size.

How Muscles Work: When you move a part of your body your muscles will either: CONTRACT – Bulge (get fatter) and shorten Or: RELAX – Return to their original length

Muscle Contraction Muscles work (contract and shorten) when stimulated (told to do so) by the central nervous system (CNS). The brain sends messages via the spinal cord to the muscles it wishes to move. The spinal cord acts like a telephone wire. Muscular tissue has the ability to contract (shorten and bulge) and then return to its original length because it has ELASTICITY. Voluntary / Skeletal muscles usually works across a joint. They are attached to both bones by strong cords called Tendons. Tendons are white, flexible, very strong and are different shapes depending upon the muscle. In other words Tendons are the cords that connect Muscles to Bone so a muscle has tendons at both ends.

Antagonistic Pairs Muscles work in pairs to provide movement for physical activity, for example the biceps and triceps work together to create movement.

Antagonistic pairs Prime movers – these muscles determine the movement of an action via contraction. For example during the bicep curl, the prime mover during the flexion phase is the bicep. Antagonistic – this muscle works together with the prime mover but creates an opposition action. Using the example of the bicep curl again, during the flexion phase the triceps enable the arm to bend at the elbow joint for the bar to move towards the shoulder girdle.

Antagonistic pairs During the downward phase of the bicep curl the opposite occurs. For example the prime mover (Agonist) is the triceps and the antagonistic muscle is the bicep.

Origins and Insertion Muscles PULL on Bones – muscles are attached to two different bones with tendons. To make a joint move – one of these bones will move but not the other ORIGIN –attached to the STATIONARY bone INSERTION – attached to the MOVING bone

Origins and insertion

Muscle Contraction Muscles contract to produce movement. There are three main types of muscle contraction: two where obvious movement occurs and one where no obvious movement is visible. Isometric contraction is where the muscle stays the same length during contraction, or when the activity is being carried out. Tension occurs in the muscle but the distance between the ends stay the same

Muscle Contraction Isotonic concentric contraction is when the muscle shortens when performing an action. There is obvious movement when the ends of the muscle move closer together. Isotonic eccentric contraction occurs when the muscles lengthen under tension. The ends of the muscle move further away during an action.