N P SPORTS MEDICINE

MUSCLES & MUSCLE ACTION P SPORTS MEDICINE

INTRODUCTION DID YOU KNOW? N P Humans have over 650 muscles which differ in size according to the jobs they do. These muscles constitute 40% of our  body weight.  The special function of muscle tissue is contraction.  CONTRACTION: a shortening or tensing of a part or organ (especially of a muscle or muscle fiber) N P SPORTS MEDICINE

TYPES OF MUSCLE TYPES OF MUSCLE N P VOLUNTARY/SKELETAL MUSCLE INVOLUNTARY MUSCLE CARDIAC MUSCLE N P SPORTS MEDICINE

VOLUNTARY/SKELETAL MUSCLE Muscle that is under the control of the will and is generally attached to the skeleton Fast acting, Powerful, Eventually will tire FOR EXAMPLE: Biceps and Deltoids N P SPORTS MEDICINE

INVOLUNTARY MUSCLE INVOLUNTARY MUSCLE N P Muscle whose activity is not under the control of the will; it is supplied by the autonomic nervous system -The part of the vertebrate that supplies stimulation via motor nerves to the smooth and cardiac muscles (the involuntary muscles) and to the glands of the body Slow acting We do not have conscious control Weak. FOR EXAMPLE: Muscles of Digestive Tract/Bladder N P SPORTS MEDICINE

CARDIAC MUSCLE CARDIAC MUSCLE N P A type of muscle with unique features only found in the heart. The cardiac muscle is the muscle of the heart and medically is called the myocardium. Own blood supply Does not tire Fast acting Powerful N P SPORTS MEDICINE

FUNCTIONING OF A MUSCLE Muscle has only one function and that is to contract. Muscles are attached to bones by tendons so when a muscle contracts it pulls on the bones that it is attached to and the result is movement of that bone. The type of movement is determined by the joint at which the bone occurs. Because a muscle can only contract it can not move the bone back to its original position, i.e. it can not relax. So muscles usually work in pairs of opposites (Antagonistic pairs). N P SPORTS MEDICINE

FUNCTIONING OF A MUSCLE (continued) Although muscles are known individually by the particular anatomical name, they are also known collectively by the type of movement that their contraction creates. E.g. When the biceps contracts it bends the arm and pulls the hand up towards the shoulder. The movement that has occurred is flexion at the elbow. So the biceps is known as a “Flexor” muscle. The opposite movement is extension and the triceps is known as an “Extensor” muscle N P SPORTS MEDICINE

MUSCLE ATTACHMENT MUSCLE ATTACHMENT N P Muscles are attached to bones by tendons. Tendons are fibrous straps that grow out of the bone and into the muscle. They are very strong and elastic, indeed the Achilles tendon is the strongest thing in the body. N P SPORTS MEDICINE

ORIGIN AND INSERTION ORIGIN AND INSERTION N P ORIGIN and INSERTION A muscle is attached to at least two bones. These two attachments are different and are known by different names: ORIGIN and INSERTION The origin is the point of attachment for the muscle to the bone that it is anchored to. The point of insertion is the point of attachment for the muscle to the bone that it moves. EX: The point of origin for the Biceps is the Scapula and the point of insertion is the radius i.e. it does not move the scapula but it does move the radius.   ORIGIN AND INSERTION N P SPORTS MEDICINE

DIFFERENT ROLES OF MUSCLE Different muscles perform different functions…sometimes at different times N P SPORTS MEDICINE

AGONIST (Prime Mover) AGONIST (Prime Mover) N P This is the muscle whose contraction and subsequent pull on the insertion tendon creates the movement EX: the hamstrings when bending the leg to run. N P SPORTS MEDICINE

ANTAGONIST ANTAGONIST N P This is the muscle that is relatively passive during the movement, but that will become the prime mover when the body part is returned to its original position EX: the quadriceps during the first part of the stride when running. N P SPORTS MEDICINE

SYNERGIST SYNERGIST N P This is the muscle that helps to stabilize the body part that is being moved. It is adjacent to the insertion tendon. EX: around the elbow during the bicep curl (Biceps is the agonist, Triceps is antagonist). SYNERGIST N P SPORTS MEDICINE

FIXATOR FIXATOR This is the muscle that provides stability at the point of origin for the working muscle, - EX: The muscles of the shoulder and upper back during the bicep curl. N P SPORTS MEDICINE

TYPES OF MUSCLE FIBER TYPES OF MUSCLE FIBER N P Muscle Fiber can be either: SLOW TWITCH – (Type 1) Endurance Fiber, works well with oxygen, aerobic Ex: Long Distance Runners FAST TWITCH – (Type 2) Power Fiber, Quick Bursts anaerobic Ex. Sprinters, Power Lifters N P SPORTS MEDICINE

Slow-Twitch Slow-twitch fibres contract slowly and can be used for longer periods of time. Postural muscle of the back are composed of mostly slow-twitch muscle fibers. Athletes who run long distances need more slow-twitch fibers in their legs. Slow-twitch muscle fibers rely on oxygen as their main energy source.

Fast-Twitch Fast-twitch fibers contract quickly and provide strength and speed, though they also fatigue more quickly. Sprinters require short but intense bursts of energy and therefore need more fast-twitch muscle fibers. Fast-twitch muscle fibers rely on ATP and glycogen as their main energy source. As ATP sources can be rapidly depleted, lactic acid is a by product of the breakdown of glycogen, fast-twitch fibers can only be active for a short period of time. .