Question

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Types of contraction - Activity Label the type of muscle contraction illustrated by the images below. I 1pt Concentric Eccentric Isometric Isometric Eccentric Concentric

Answer 1

All the answers are correct 1) Eccentric 2) Isometric 3) Concentric

EXPLANATION:

MUSCLE CONTRACTION: Any activity increases the intramuscular tension and changes in the muscle length. The Muscle fibers are contracted and relaxed during the muscle work. Depending upon change in the length and tone of the muscles contraction is divided into three categories:

1) Isotonic contraction

​​​​​2) Isometric contraction

3) Isokinetic contraction

1) ISOTONIC CONTRACTION: Isotonic contraction is the type of contraction with change in length of the Muscle. There are types of isotonic contraction : a) Concentric contraction b) eccentric contraction

concentric contraction: This type of contraction is otherwise called shortening contraction. In these contraction muscle shortens to generate tension. The proximal and distal components are drawn towards the center. Energy expenditure is more in this contraction.

Example: Biceps curls - lifting the dumbbell ( flexion of elbow against gravity)

Eccentric contraction: This type of contraction is otherwise called lengthening contraction. Here the proximal and distal components are pulled apart from the center. Energy expenditure is less in this contraction because of gravity assistance.

Example: In biceps curl, lowering of dumbbell from flexion to extended position of elbow.

2) Isometric contraction:

In isometric contraction there is no changes in length of the muscle but muscle tension is increased. Intramuscular tension is increased without change in muscle length. Both the proximal and distal components are fixed here. Energy expenditure also low.

3) Isokinetic contraction:

In Isokinetic contraction the velocity and speed is same and the resistance is variable. These type of contraction can be done only with the help of special equipment such as biodex or dynamometer. It is mostly used in sports field.

KEY POINTS TO REMEMBER:

1) Isometric contraction: no change in length but tension( force) developed.

Example: Holding a book in 90 degree elbow flexion

2) Concentric contraction: shortening contraction/ against gravity/proximal and distal ends comes together

Example: Lifting a book from the table. Biceps work concentrically

3) Eccentric contraction: Lengthening contraction/ movement towards gravity/ proximal and distal ends drawn away

Example: Placing a book back to the table. Biceps work Eccentrically.