A:  We prefer SLDL's only because the awkwardness and potential for poor form/ injury can really hamper a good experience and results. The load can be much higher with SLDL's as opposed to GM's and you can keep a tighter form because you're doing half the range. You can also feel that the weight is less stable in GM's - feel as if it's rolling around when it may or may not be. But the potential is there. GM's in our opinion are injuries waiting to happen unless you have a great base for lower back strength to begin with. We just think that for the average person, GM's are really a crap shoot for the low back and spine itself. We know too many people who have had bulging disks emerge from doing years of GM's. Placing stress on the low back is the point, but not to the point of injury. 'Nuff said.