Move and Positioning

The wording of your question doesn't make sense, so I'll assume there's been a type o and try to answer what I think you're asking.
For persons who cannot independently change the position of their body - whether in bed, in a chair, in a wheel chair, or wherever they may be - their muscles lock up causing excruciating pain. You would recognize this pain if you've ever had your arm in a sling for 3 days. The pain is so severe from lack of motion in stabilizing the joint that it takes several trips to the physical therapist to work the joint back into motion and several more trips to restore full range of motion. And it's very difficult for the person to do the exercises needed to unlock the joint and restore ROM.
Range of Motion - when you are sitting at your computer and your neck gets tight, you bend it forward and back, then probably around in a full circle, stretching the muscles and loosening up cramps. If you begin the head roll and at any point, there is sharp pain or resistance and you cannot flex all the way, you have experienced a decreased range of motion. When you are young, you stretch and touch your toes, reach behind you and scratch the upper middle of your back.. with age, this becomes increasingly difficult, until you can no longer reach because of decreased range of motion. So it does not have to be an injury that causes it.
In a hospital setting, I worked with comatose patients, patients with Traumatic Brain Injuries (TBI), Orthopedic (post-surgical - mostly hip replacements), spinal cord injury, the elderly, etc. On the Brain Injury Unit, we administered ROM exercises every day in an attempt to assist our patients with retaining some, if not all of their ROM. Arm flexion and extension, leg flexion and extension, hands, feet, etc. This did not prevent their joints from locking up,  

Additional Details added 1 year ago

It helped immensely, though. With repositioning, there are several reasons involved. Is the seatbelt on the wheelchair...