Muscular System
Types of Muscle
Skeletal muscle (voluntary): Gives form to the body and helps to produce movement.
Cardiac Muscle (involuntary): Forms the wall of your heart
Smooth Muscle (involuntary): Forms part of the walls of most vessels and hollow organs
Skeletal Muscle
Muscles attach to bones via tendons, when your muscle contracts the movement happens across that joint pull in the direction of the muscle fibres causing movement.
Origin: is where the muscle starts (originates from). It often referred to as the proximal attachment point.
Insertion: is where the muscle ends (inserts). Commonly known as the distal attachment.
Muscle Terminology
Agonist or Prime mover: Contracts/ shortens which creates movement. Example during in a bicep curl, curling the weight towards your shoulder.
Antagonist: A muscle that opposes the action of the prime mover. Example lowering the weight in a bicep curl.
Assistor/Synergists: Complements the action of the prime mover. This includes the secondary muscles involved the movement.
Stabilizer: Contract to keep the proximal parts of your body stable while movement is happening.
Reciprocal Inhibition: The law that when one muscle contracts the antagonist must has to relax in order for contraction to occur.
Basic Types of Muscle Fibers
- Slow Twitch/Type 1: Aerobic, important for endurance activities (e.g. running long distance).
- Fast Twitch /Type IIb : Anaerobic, power and speed (e.g. power lifting, sprinting and shorter explosive movements)
- Intermediate Type IIa : can be trained to act like either fast or slow twitch fibers depending on training
Types of Muscle Contractions
Concentric – muscles shortens and contracts creating movement in the joint
Eccentric – Muscles lengthen
Isometric – Joint does not move while muscles contract.
