Types of Muscle Contractions

concentric muscle contraction

concentric muscle contraction

isometric muscle contraction

isometric muscle contraction

eccentric muscle contraction

eccentric muscle contraction

There are three important types of muscle contractions:

Concentric (muscle shortening): When your muscle exerts more force than is being placed upon it, your muscle is strong enough to shorten and therefore move the associated part of your body. This is also known as flexion and happens when you “successfully” contract your muscle(s).

Isometric (neither shortening nor lengthening): When your muscle exerts a force equal to the force being placed upon it, your muscle neither shortens nor lengthens, remaining static but still active. This is also known as dynamic stabilization.

Eccentric (muscle lengthening): When your muscle exerts less force than is being place upon it, your muscle is not strong enough to shorten and instead lengthens. This is also known as extension and happens when you relax your muscle(s). This is even sometimes referred to as negative muscle work. See also: The Importance of Eccentric Muscle Movement (<— coming soon)

 

EXAMPLE (biceps muscle): You have your elbow at your side and your forearm and hand outstretched with your palm up. You are handed three different objects:

An apple:
In this case, you are able to move your forearm toward your chest, raising the apple toward your mouth to take a bite. In this case, you are able to do so because your biceps muscle is able to exert more force (is stronger) than the force being placed upon it (the weight of the apple and gravity). So, your biceps muscle contracts and shortens, allowing you to lift the apple toward your mouth This is an example of a CONCENTRIC contraction of your biceps.

A large dictionary:
With this particular dictionary, your hand neither raises nor drops. This is because your biceps muscle is able to exert the same amount of force (muscle strength) as the force being placed on it (the weight of the dictionary and gravity). So, your biceps muscle contracts but no movement occurs. This is an example of an ISOMETRIC contraction of your biceps

A bowling ball:
Now, your forearm slowly (or quickly depending on how heavy the bowling ball is) starts to drop away from you toward the floor. This is because your biceps muscle is not able to exert more force (is weaker) than the force being placed upon it (the weight of the bowling ball and gravity). So, your biceps muscle contracts but lengthens, dropping the bowling ball away from you. This is an example of an ECCENTRIC contraction of your biceps.

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