The one-arm row is a classic exercise, but it can usually be performed better by pulling with a J-shaped trajectory.
One concept in muscular anatomy that's often overlooked is the direction that fibers run. Muscles contract along the lines of fibers within them. So, muscles only contract in the direction those fibers run.
In the case of the lats, the fibers run a bit diagonally from the shoulder joint down towards the lumbar spine. So it's important to use those fibers that are high up in the back (and diving into the shoulder joint) by letting a weight travel in front of us during rows.
How to Do It
- Get one knee on a bench with the same-side arm directly underneath the shoulder joint. Your off-bench leg should shoot out wide to "get out of the way" and create a pocket for the elbow.
- Engage your core and brace to keep your spine level (tabletop back).
- Let the dumbbell begin underneath your forehead/eye region and pull it towards your hip.
- Move it back towards the hips, up towards the ceiling, and then in towards the spine.
- Slowly control the weight back into that stretched lat position.