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 increasesB.) muscle cells form more mitochondria and are able to store more Oxygen

Benefits of Aerobic Exercise

1.) More efficient body metabolism2.) Improves digestion3.) Enhances coordination4.) Strenghtens the skelelton5.) Enlarges the heart :

a.) more blood pumped out

b.) less fat in blood vessels (arteries/veins/capillaries)

c.) better gas exchange of O2 CO2

Resistance Exercise

You may know resistance training as “Lifting Weights”

Resistance ExerciseMuscles 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

Abduction Adduction

Opposing Movements

Prime Mover vs. Antagonist

Pronation Turning the palm over to face the palm tothe floor

SupinationTurning 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, allowingthe 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