Active and Passive Insufficiency
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. This is referred to as muscle insufficiency. It can either be passive or active.
The active insufficiency of a muscle that crosses two or more joints occurs when the muscle produces simultaneous movement at all the joints it crosses and reaches such a shortened position that it no longer has the ability to develop effective tension. When a prime mover (agonist) becomes shortened to the point that it cannot generate or maintain active tension, active insufficiency is reached.
- The shortening of the Rectus femoris limits full hip flexion when the knee is fully extended.
- Maximal shoulder flexion cannot be achieved simultaneously with maximal elbow flexion due to the shortening of the Biceps brachii.
- Maximal knee flexion and maximal plantar flexion are limited due to the shortening of the gastrocnemius.
- Full knee flexion and full hip extension cannot be achieved simultaneously due to the shortening of the hamstrings.
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.
- Full knee flexion is limited by the stretching of the Rectus femoris if the hip is fully extended.
During rehabilitation, each joint should be moved individually through its available range of motion in order to optimally improve or maintain the amount of range of motion at that joint.
- Clarkson HM. Musculoskeletal assessment: joint range of motion and manual muscle strength. Lippincott Williams & Wilkins; 2000.
- GUStrenght. What is Active Insufficiency of Muscle. Available from: https://youtu.be/FT7OABz8I5k
- 1. Rogers M, Rogers M. Understanding Active and Passive Insufficiency [Internet]. National Federation of Professional Trainers. 2020 [cited 17 September 2020]. Available from: https://www.nfpt.com/blog/understanding-active-and-passive-insufficiency
- Dr. Veronica Foster. Biomechanics Lecture 19 - Active and Passive Insufficiency. Available from:https://youtu.be/vCEYDZvox2s