there are situations a muscle cannot function sufficiently um and then we call this as muscle insufficiency and we uh typically categorize them as active muscle insufficiency and passive muscle insufficiency what is M muscle active insufficiency this happened uh particularly for a muscle that is across multiple joints uh one example here is the hamstring we know the hamstring when they act as the acist um they help extend the hip and flex the knee when we um extend the hip um separately from uh flexing the knee the the hamstr has no problem performing this when we ask the hamst streams to do the both movement at the same time then uh this is something that we can observe that uh the muscle cannot uh bend the knee to the end range that we hope or extend the hip to the end range that we hope this is what we call Active insufficiency and why does this happen because when we talk about the length and the myosin acting uh bounding reaction this is um not hard for us to imagine that this is when the myosin acting not they're so close to each other there's no more cross bridge that U that is available uh for the hamstring to produce more uh tension let's continue to use hamst stream in another example but this time the hamstring functioning um as the antagonist so we know uh hamstring uh when they're uh functioning as the acist uh the um the the muscle functioning as the hip flexion and um sorry knee flexion and hip extension so when they're acting as the antagonist is the the the opposite direction so when uh the person is trying to bend to to touch the toe um the person is trying to bend the hip and extend the knee this is very difficult compared to when uh this person bend the knee a little bit they can easily to touch the toe so this is when the hamstring is being stretched and why is this hard because the meotine uh and actine are myosin and actine are far from each other so it's hard for the abounding U action to be uh happening and this this mechanism is um actually a protective uh mechanism to protect the muscle being you know damaged but also this is um um what we call passive insufficiency in this situation like this why do we need to know though why do we need to know the situation of active insufficiency versus passive insufficiency in clinical practice um the example that I gave you that I give you here is uh for an individual with a spinal injury and specifically this person is uh C6 uh damage in C6 um the client has movement of risk extension but not much for wrist flexion and not to mention the finger movements so uh but we want to help this person to be able to use their hand right so what we can do is to ask this person to relax and the gravity will bring the wrist down to create this rist flection and because of the passive insufficiency the uh finger extensor um finger extensors are being stretched and because of the length uh limitation uh when uh this extensor finger extensors are being stretched um um this actually helped this person to open the hand right when we ask the person to perform wrist extension because of that passive insufficiency that would actually close the fingers to create this kind of grasping kind of movement going on so this is what we uh take advantage of passive insufficiency of the finger extensors for individuals with spinal injury and clinically uh we call this movement as uh T Teno disas so when you hear people um talking about Teno disis you should uh refer to the passive insufficiency that we take advantage out of finger extensors specifically uh for uh people with spinal corn injury we can also use um this type of knowledge of uh muscle length uh in another uh scenario uh clinically so if you working with a client who has you know not so good posture like this person um showing here we know um in this uh posture um the back muscle is are being stretched and the uh chest muscle um the peack muscles are actually a shortening so we know um to counteract or to correct this um uh posture we can provide some muscle strengthening to the uh stretched muscle because when the muscle is being stretched they become weaker right so we can actually prescrib some some kind of muscle strengthening to the stretched muscle and what do we do for the PE muscles that are short turned we can stretch the the uh the PE muscles right but so in this situation we can prescribe some kind of stretching exercise to actually stretch the PEC minor and pec major so that this person can regain um a proper muscle tension for U the task that they need to do