Isometric Contraction= muscle increases in tension, no movement at the joint, muscle is moving while contracting,no visable shortening or lengthening.
Example: holding a barbell with the elbows flexed at 90 degree. (biceps contract isometrically)
Concentric Contraction= muscle shortens under tension, movement is produced around a joint, force exerted is greater than the resitance, muscle shortens while contracting.
Example: upwards phrase of a bicep curl (Bicep Brachii contract concentrically)
Eccentric Contraction= muscle lengthens under tension, helps control movement at a joint, force exerted is less then the resistance, muscle lengthens while contracting.
Example: downwards phase of a bicep curl.
-eccentric contraction of the biceps during downwards phrase is used to counteract force of gravity.
-gravity acts on mass weight and forearm, causing extension at the elbow.
-If bicep did not contract to control the rate of motion caused by gravity, the movement woud be quick, causing injury!!
- muscle contracts eccentrically acts as a brake to counteract effect of gravity.
- triple jumpers quadriceps muscles must contract eccentrically on landing during hop step phrase to stop the legs buckling and preventing the jumper from collapsing to floor.
Antagonistic Muscle action...
-Muscles never work alone, several muscle work at one time.
-muscle that produces desired movement is agonist/prime mover.
example= flexion of elbow, muscle responiable for the flexion is bicep brachii.
-in order for the bicep muscle to shorten when contracting, the triceps muscle must lengthen. tricep in this instance is known as the antagonist. (action opposite to that of agonist)
The two muscles work together to produce requied movement.
Fixators muscles and stabilisers also work in this movement. role is to stabilise orgin so that the agonist can achieve max and effective contraction.
Neutalisers or synergist in this movemnt prevent and undesired movements which may occur at the shoulder when biceps are working over two joint.
Commonly used antagonistic pairing,,,
anterior deltoid/ posteriar deltoid
rectus abdorminas/ erector spinalis
quadriceps groups/ hamstring group
tibialis/ gastrocenemius and soleus
wrist flexors/ wrist extensors