Muscle Activity

Question 1

With reference to muscle activity, briefly explain the following term and give an example of the appropriate movement produced by a specified muscle to support your answer:
Isometric muscle work

Answer 1

Also called static muscle work where there is an increase in tension/activity within a muscle sufficient to resist any externally applied force but there is not alteration in muscle length and no movement occurring at the joints associated with the muscle.
EG. In normal standing with a stationary elbow joint which is flexed to 90 degs and holding heavy book in the hand Biceps Brachii will display isometric muscle work

Question 2

With reference to muscle activity, briefly explain the following term and give an example of the appropriate movement produced by a specified muscle to support your answer:
Concentric muscle work

Answer 2

When an active muscle shortens bringing the attachments closer together resulting in movement of the associated joint and a swelling of the muscle belly.
EG. In normal standing with an elbow joint which is flexing from 10 degs to 150 degs and holding heavy book in the hand Biceps Brachii will display concentric muscle work overcoming the weight of the book to create movement against resistance

Question 3

With reference to muscle activity, briefly explain the following term and give an example of the appropriate movement produced by a specified muscle to support your answer:
Eccentric muscle work

Answer 3

When an active muscle lengthens with the attachments moving apart resulting in movement of the associated joint and a swelling of the muscle belly.
EG. In normal standing with an elbow joint which is extending from 150 degs to 10 degs and holding heavy book in the hand Biceps Brachii will display eccentric muscle work controlling movement created by the weight of the book and the force of gravity

Question 4

With reference to muscle activity, briefly explain the following term and give an example of the appropriate movement produced by a specified muscle to support your answer:
Isotonic Muscle work

Answer 4

In an isotonic contraction, muscle tension remains unchanged and the muscle’s length changes. There are two types of isotonic contractions: concentric and eccentric. In a concentric contraction, the muscle tension rises to meet the resistance, then remains the same as the muscle shortens. In eccentric, the muscle lengthens due to the resistance being greater than the force the muscle is producing.

Question 5

With reference to muscle activity, briefly explain the following term and give an example of the appropriate movement produced by a specified muscle to support your answer:
Reciprocal muscle lengthening

Answer 5

When a primemover/agonist muscle produces concentric muscle activity the antagonist is reciprocally inhibited and will lengthen. When Biceps shortens via concentric contraction the Triceps will under go Reciprocal muscle lengthening