One common thing I've found in media is that when a character has been immobile for an extended period of time (for whatever reason) they are able to pop right up as soon as the moment presents itself.

That's not how it works.

Muscles that don't get used get lazy.

Fast.

If any of you have been on a car or plane ride that's lasted several hours have probably felt achy when you've stood and exited. Now imagine if you don't have the option to even shift positions or stand up momentarily. Kept that way for even a few hours, a person's legs will not be in prime condition to jump up and run off to do the next thing.

They will be stiff. They might buckle. They will ache.

Another common whump I've seen is where characters are secured in place by their wrists above their head. If someone is bearing their full weight on their wrists this is going to hurt very very quickly. Arms were not made for that and it won't take much for the shoulders to become dislocated which is in itself another painful injury. Even if someone's weight isn't fully on the arms it's still uncomfortable as blood drains from the arms and numbness sets in. Then when the arms are released there's going to be feelings of pins and needles which can range from uncomfortable to painful depending on how long the limb has been without adequate blood flow.

- Also when someone is dangling they're at an increased risk of asphyxiation (inability to breathe). The lungs use gravity and alternating air pressure to move air in and out of the lungs. When someone is suspended the force on the torso is a lot greater. This restricts the amount of air that can come in and forces the person to lift up (as much they can) to relieve the pressure. (Ex: The Roman torture of crucifixion capitalized on this fact. If a person didn't die because of blood loss from earlier torture they would die because they couldn't lift themselves up to breathe)

Extended immobility is typically caused by illness/injury/advanced age and I haven't seen as many instances in the stories I've come across, but for anyone who's wondering here's some long term effects of prolonged immobility:

It only takes three days for muscles to start atrophying ("waste away"). In health care settings if someone is unconscious or unable to move for various reasons they might have people perform range of motion exercises on them to make sure their limbs don't lose the ability to function as they're supposed to. If a limb is "flexed" for too long, it can lose its ability to extend completely. Hand contractures and foot drop are two examples.

Immobility can also cause skin breakdown (pressure ulcers). These typically happen at the bony prominences of the body that take the most weight when a person is sitting or laying down. The most common places this is seen is at the tailbone and heels, but shoulders, hips, back/side of the head. For people who are unable to shift themselves in the health care setting they have to be repositioned every 2 hours. In a healthy young individual it will take longer for that to happen than an older adult (or if someone has a chronic condition like diabetes) but it's still a possibility.

Deep vein thrombosis (blood clots) are also a risk since walking helps push the blood from the legs back up to the heart. If the blood is still for too long that's when clots can develop.

There is also an increased risk of lung infection. Lungs that don't have to expand fully also get lazy which decreases the surface area that CO2 and O2 can be exchanged. This can lead to pneumonia. Another danger is if a blood clot from the leg breaks loose there's the risk of it going through the heart and lodging in the lungs. When that happens it's called a pulmonary embolism and is a HUGE medical emergency.

Lastly there's physiological factors. Boredom, depression, hopeless/helplessness, anxiety, anger, and -if it's due to a long standing illness/injury- disturbed body image can all occur for someone who's been unable to move freely for long periods of time.