3. Crunches
Crunches are a good way to work out to abdomen and core muscles, and many people do them to get a slimmer physique. They are also a convenient exercise because you can do them almost anywhere. While crunches do work out the stomach muscles, they also work out the lower back muscles.
Every crunch pulls on the lower back muscles and has the potential to cause or aggravate an SI joint problem. Crunches require the lower body to come up off the ground, and this can put a lot of pressure on the sacroiliac joint and supporting ligaments. It can lead to sudden and severe pain during the crunch or more chronic and deeper pain after.
It can take months to recover from a torn ligament or an SI joint injury. There are other exercises that can help you get in shape and tone your body without harming your SI joint.