I'm using briefs for both squats and sumo pulls in my next training block. It's been a while since I've worn them consistently, and in a recent session I was wearing them for sumo pulls (using a stiff power bar) and it reminded me of how much feedback briefs give and how much that can help your technique.
My first few pulls were slow and uncomfortable. But as I warmed up and really sat down into the briefs, and loaded up through my spine, the bar was flying off the floor, even before I started my pull.
Generating tension is a tough concept for some lifters. And I realized that wearing gear on and off through raw training taught me a lot of those principles.
The gear provides feedback directly- through physical sensory input - you can use the briefs to find the proper position for your hips. But it also generates force that you have to fight against in order to maintain your technique. It's not easy, and for that reason I'd recommend a lighter or looser pair of briefs to start with. But once you're able to find the tension, then you fight the tension. And your body, the gear, and your leverages all work together to move the weight. Then the trick becomes doing it with no gear.
Notice as I pull into position the bar is leaving the floor - "Pulling the slack out"
[youtube=http://www.youtube.com/watch?v=pZi5VcKS6Ac]
Same pull, just slow mo:
[youtube=http://www.youtube.com/watch?v=Av8VtaZlLkY&feature=youtu.be]
