Morning all. I seem to have a problem in my abs in that I can't train them for more than 1 set without the lower portion mainly locking up. It's absolute agony for about a minute then they slowly relax but if I tense them again they do the same. I never have any issues with compound lifts and nothing else on my body does it. I managed to get through a small workout on them today but new if I pushed to where I wanted to they where going to lock as they nearly did. Any input on what the hells going on or a remedy for this would be appreciated. It's happened on Cable crunches, knee raises, crunches and leg raises so it's not just one movement causing it.