What workout to master this year! One-arm, One-leg Bentover Dumbbell Row Why you should master it: Because your hamstrings are tight and you spend little time on them. With this move, you stretch the hammies in the same time you’d spend with a traditional row. Plus, you’ll be doing a move that nobody else in the gym will do. How to do it: A variation on the traditional one-arm row, this has you bent over with your nonlifting hand balanced on a dumbbell rack or bench. Extend the corresponding leg of your lifting hand back. Do a set of 10, and then switch sides.