Active and Passive Insufficiency

Original Editor - Innocent Abugu

Top Contributors - Innocent Abugu, Lucinda hampton, Kim Jackson and Alicia Fernandes  

Introduction

The amount of force or tension generated by a multi-joint muscle (muscle that crosses two or more joints) diminishes as the muscle moves the joints simultaneously. Muscle insufficiency is a condition in which a muscle is unable to exert its normal force and bring about movement of the part to which it is attached. It can either be passive or active.

Active Insufficiency

When a prime mover (agonist) becomes shortened to the point that it cannot generate or maintain active tension, active insufficiency is reached. Active insufficiency occurs when a multi-joint muscle shortens over both joints simultaneously, hence, creates so much slack, that muscle tension is almost completely lost.

• The hip cannot be fully flexed, and the knee fully extended simultaneously, because of the shortening of the rectus femoris.

Hip flexion without knee extension

Hip flexion together with knee extension (Active insufficiency)

• Maximal shoulder flexion cannot be achieved simultaneously with maximal elbow flexion due to the shortening of the Biceps brachii.
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Passive Insufficiency

When the opposing muscle (antagonist) is stretched to a point where it can no longer lengthen and allow further movement, passive insufficiency is reached. Passive insufficiency occurs when a multi-joint muscle is lengthened to its fullest extent at both joints, but also preventing the full range of motion of each joint it crosses.

• Full finger flexion cannot be achieved if wrist flexion occurs simultaneously.
  

• Maximal hip flexion and maximal knee extension are limited by the lengthening of the Hamstrings.