The half sit up is an exercise that is rarely integrated into a physical therapy program. There's a number of things that can go wrong during a half sit up. Namely the pressure on the spine, the head and neck position during the exercise, and as well as the timing of doing the exercise. Patients are often thinking about strengthening their core when they're dealing with their back pain which is often a big misconception and hopefully they're going to enter a physical therapy clinic to deal with their pain. But if they're not the partial half sit up is never something I recommend when you're dealing with the pain. So lets put your hands behind your neck. A half sit up is an exercise where you're going to do an abdominal crunch first, and hold that stomach muscle and at the same time pulling up, your shoulders, and neck and your scapula and then coming right back down.
It's an exercise we learned even as a kid when you're in gym school, or gym class and it's something that people remember along the way, but again it is a difficult exercise for patients that are having back pain and the pressure that you're placing on your lower back during the exercise is often incorrect and it can further exacerbate the problem. You're increasing the pressure inside the disc and inside the joints and you're forcing the tissue in a direction that is very similar to why the patient is suffering in the first place which is too much bending or carrying or sitting in general. And again also patients can walk away with a little bit of neck discomfort as well if you're not being careful using your head and neck appropriately. So the partial or half sit up often is considered a bad exercise in the physical therapy clinic especially during the acute and sub-acute phases of the injury.