WHAT IS ACTIVE
INSUFFICIENCY?
Any muscle that crosses over more than one joint is capable of producing
force at more than one joint. Makes sense right? I mean, that’s what muscles
do. They generate force, either to move us around or lift things, or provide
stability. What most people don’t realize is that a muscle can only shorten by
a certain amount, typically up to 50% of its resting length. What this means is
that if a muscle is already shortened about one joint, then it cannot
forcefully contract to produce movement over the other joint that it crosses.
This is referred to as ACTIVE INSUFFICIENCY, and explains a lot about why
certain muscles are more or less active at certain joint angles.