1.5 - Types of Muscle Contractions (Stretching)
Description
This article is from the Stretching FAQ, by Brad Appleton Brad_Appleton@ivhs.mot.com with numerous contributions by others.
1.5 - Types of Muscle Contractions (Stretching)
The contraction of a muscle does not necessarily imply that the muscle
shortens; it only means that tension has been generated. Muscles can
contract in the following ways:
"isometric contraction"
This is a contraction in which no movement takes place, because the
load on the muscle exceeds the tension generated by the contracting
muscle. This occurs when a muscle attempts to push or pull an
immovable object.
"isotonic contraction"
This is a contraction in which movement *does* take place, because the
tension generated by the contracting muscle exceeds the load on the
muscle. This occurs when you use your muscles to successfully push or
pull an object.
Isotonic contractions are further divided into two types:
"concentric contraction"
This is a contraction in which the muscle decreases in length
(shortens) against an opposing load, such as lifting a weight up.
"eccentric contraction"
This is a contraction in which the muscle increases in length
(lengthens) as it resists a load, such as pushing something down.
During a concentric contraction, the muscles that are shortening serve
as the agonists and hence do all of the work. During an eccentric
contraction the muscles that are lengthening serve as the agonists
(and do all of the work). (See "1.4 - Cooperating Muscle Groups").
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