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