All of the above that AXA-tic questioned. And more, including thegrip, hips/butt, legs/hams and pretty much down to the feet. It is a superior full body compound exercise. One does not have to start DL's off the floor. Take them from around the knee (a little above a little below), depending on the body mechanics of the lifter, for favorable benefits. If your into PL'ing than DL's have to be from the floor position. But partial rep's ( knee area) also help. Even 3 to 4 inch partial lifts assist greatly with power and size. Adding shrugs at the finish standing position gives even more development.
With the DL, you are holding the bar stable and in position while the hips/butt legs, etc do the actual lifting. Looking at it closely, notice that there is a push off the floor by the lower body, not a pull. If doing a SLDL (a outstanding exercise) than more of a pull is involved. All in all, I prefer the SLDL...just a personal view.
The regular DL is not for everyone. But there are many versions of DL'ing suited for different body types. Main hazard in the regular DL is leaning too far forward to avoid hitting the knees during a exercise lift. Leaning too far forward places too much tension and strain on the lower back. As The Coach suggest, a trap/shrug bar works well because, for the most part, the knees are taken out of the line of the lift. Heavier DB's could also be used for a period.
There is also special equipment like the devices used when training for the Farmers Walk, with handles on them. Extra plates can be added to the basic weight of this equipment. Men, in the past, have constructed home made equipment from 4X6's ( or what ever) with cross member braces. Drill some holes and add any form of handles you wish (large "U" bolts may work here). May not look like it but you now have a very functional piece of DL'ing equipment. Just step inside the frame, grap the handles and lift. Good Luck.
