Answer
There are two main types of muscle contraction, isometric and isotonic. There are also two subdivisions of isotonic contraction, concentric and eccentric. In isometric contractions the muscle changes length but its tension remains the same. In contrast when a muscle contracts isometrically its tension changes but its length remains the same.
The following are examples of isometric contractions:
a. Holding the plank yoga posture
b. Glute bridge pose
c. Stand two to three feet facing a fall. Lean forward supporting your weight with both palms placed against the wall. keep arms stretched fully; retain position for two to three minutes that position for 30 seconds to one minute
Work Step by Step
Isotonic Contractions:
In concentric contractions; tone of muscle does not change the muscle shortens as it does work. Examples are the biceps curl and the abduction of the arm by the deltoid. In eccentric contractions, the tone of the muscle does not change, but the muscle lengthens as it does work. The adduction of an upper limb by the deltoid is an example this subtype of isotonic contraction; also, in lowering a weight from a biceps curl, the elbow flexors lengthen to control the lowering of the weight.
