Muscles and Movements

• How muscles work to create movement

• Types of muscular contractions

How muscles work• All skeletal muscles create movement

by pulling on the bones they attach to• Muscles can only pull, they can never

push• Muscles work in opposing pairs, where

one causes the movement while the other controls it

• Example – biceps / triceps

Reciprocal Inhibition

• One muscle contracts while the other relaxes and causes the limb to move

• More examples – hamstrings/quadriceps– pectorals (chest) / trapezius (upper

back)

Pairs of Muscles• Muscle doing the work = AGONIST• Muscle relaxing = ANTAGONIST• Example 1 – arm curl (upwards): • Agonist = biceps / Antagonist = triceps• Example 2 – standing up after a squat: • Agonist = Quadriceps / Antagonist =

Hamstrings

Types of Contractions

Isotonic• muscle length changes during contraction

Isometric• muscle contracts and its length stays

same

Isotonic Contraction

Concentric• Muscle length shortens during contraction• Bending of the joint• Example – biceps during arm curl (upwards)

Isotonic Contraction

Eccentric• Muscle lengthens during contraction• Straightening of the joint• Example – biceps during arm curl

(downwards)

Isometric Contraction

• Muscle applies a force without changing its length

• Example – quadriceps during a wall sit, work very hard to prevent body from sliding down the wall to the floor

- static balance in gymnastics