I haven't done them enough to know, but given the fact that I'm going to start doing them, this is a good question. When doing deads, do you get more sick to your stomache or more of a headache/light-headed feeling, or both? I've never done deads very much because my legs need a full week of rest before hitting them again, and I found that deads taxed them too much, so that I wasn't as strong as I'd normally be when I'd go to do legs again. But now my squats are getting really heavy and I'm having trouble with lower back pain because my legs are too strong for my lower backs good, I shouldn't have neglected it.