Posted in: Workouts / Workout Programs

FB Strong - Core Days

I just purchased FB Strong and will be starting it in two days. I was looking through my calendar and saw the core workouts. Because of a lower back injury, most crunches and core exercises really hurt my back. I'm wondering if it would be ok to do a HIIT workout on these days instead of doing the core workouts? Has anyone added HIIT to the program or would that not be beneficial? Just wondering. Thanks in advance!