Reverse sled drags are a great bang-for-your-buck exercise that serves as both a rehabilitative tool and a muscle/strength builder. They burn like crazy while you're doing them, but since there's no eccentric component, they don't leave you crippled with soreness so you can do them frequently, several times per week.
In this variation, row the sled toward you, then keep your elbows pulled down and back. Keep your hands pinned to your sides as you walk backwards.
The purpose of this column is tri-fold. Purpose number one is as a "refresher course" for seasoned lifters. Sure, deep down, you may know this stuff, but it's been so long since you first read about it that you've forgotten the rationale behind the subject matter.