Muscle Activity -- Understanding muscle actions --Benefits of Aerobic Exercise --Types of muscle contractions

Types of muscle contractions Isotonic Contractions  Myofilaments slide, muscles shorten, movement occurs Isometric Contractions  Muscles do not shorten *Tension in the muscle increases, but filaments don’t slide Muscle Tone  Continuous, partial contraction *Occurs when some fibers of a relaxed muscle are still contracting

How does exercise affect your muscles?  Inactivity  leads to weakness, then atrophy  Regular Exercise  increases size, strength and endurance  Aerobic Exercise  results in stronger, more flexible muscles that resist fatigue A.) muscles blood supply increases B.) muscle cells form more mitochondria and are able to store more Oxygen

Benefits of Aerobic Exercise 1.) More efficient body metabolism 2.) Improves digestion 3.) Enhances coordination 4.) Strenghtens the skelelton 5.) Enlarges the heart : a.) more blood pumped out b.) less fat in blood vessels (arteries/veins/capillaries) c.) better gas exchange of O 2  CO 2

Resistance Exercise You may know resistance training as “ Lifting Weights ”  Resistance Exercise  Muscles are pitted against a semi- immovable object  Increased Muscle Size  because of enlargement of each muscle cell and it’s connective tissue

All Skeletal Muscles…. “The Golden Rules” 1.) A muscle must cross at least 1 joint 2.) Usually, the muscle bulk lies proximal to the crossed joint 3.) All muscles have at least 2 attachments 4.) Muscles can only pull 5.) During a contraction: Insertion moves toward the origin Origin  attaches to the less movable bone (proximal) Insertion  attaches to the movable bone (distal)

Muscle Movements Prime Mover  Major responsibility of a particular movement Antagonist  opposes or reverses a movement Synergist  Assists a prime mover Fixators  specialized synergist that holds a bone in place to stabilize Prime Mover Contracts  Antagonist Relaxes

Opposing Motions Think of the actions of: Biceps Brachii vs. Triceps Brachii What movements are occuring during those motions?

Opposing Movements Prime Mover vs. Antagonist  Flexion  decreasing the angle at the joint  Extension  increasing the angle at the joint Where do these motions occur?  Knees, Elbows, Fingers, Toes

 Flexion Extension

Opposing Movements Prime Mover vs. Antagonist  Abduction  Moving a limb away from the body’s midline  Adduction  Moving a limb toward the body’s midline Where do these motions occur?  Shoulder, Hip

AbductionAdduction

Opposing Movements Prime Mover vs. Antagonist  Pronation  Turning the palm over to face the palm to the floor  Supination  Turning the palm up to the the ceiling Where do these motions occur?  Wrist

Opposing Movements Prime Mover vs. Antagonist  Plantarflexion  Pointing the toes away from the shin  Dorsiflexion  Bring toes toward the shin to expose the palmar surface of the foot Where do these motions occur?  Ankle/Foot

Opposing Movements Prime Mover vs. Antagonist  Inversion  point toes toward the other foot  Eversion  Point toes away from the other foot Where do these motions occur?  Ankle/Foot

Opposing Movements  Circumduction  combining movements to produce a circular motion (cone-like) Where?  Shoulder/Hip  Rotation  neck motion allowing on an axis, allowing the person to look either left or right Where?  Neck, Spine  Deviation  movement of the wrist to one side or the other (to the radius, or to the ulna) Where?  Hand/Wrist

 Circumduction   Rotation Deviation