Feeling miserable. I have been injury free for a while (since knee probs which prevented me from doing my beloved running). I have been going to the gym and mainly doing spinning, HITT and abs training which I love! Think I pushed it a bit with weighted sit-ups now my lower back is constantly niggling. I had to pull out of my class today now feel I am doooomed! Anyways, apart from planks what other exercises are great for abs that I can do whilst in semi recovery?