Muscle Action

Question 1

With reference to muscle action, explain the concept of
Active insufficiency
Give an appropriate example to support your answer and suggest how the insufficiency maybe avoided.

Answer 1

Active insufficiency occurs in a two-joint agonist muscle when it cannot shorten enough to cause full range of motion of both of the joints it crosses at the same time.
Examples: - Hamstrings during knee flexion and hip extension
- gastrocnemius during ankle plantarflexion and knee flexion

Question 2

With reference to muscle action, explain the concept of
Passive insufficiency
Give an appropriate example to support your answer and suggest how the insufficiency maybe avoided.

Answer 2

Passive insufficiency occurs when an antagonist muscle cannot be stretched/lengthened enough to permit full range of motion at both joints it crosses at the same time. Examples: - Biceps Femoris during knee extension and hip flexion - Rectus Femoris during knee flexion and hip extension