Support yourself on a bench with one arm and one knee to position your trunk approximately horizontal with a dumbbell hanging in your free arm. Row the dumbbell up by retracting the shoulder blade and pulling the elbow as high as possible—allow the weight to hang below the elbow. Squeeze your upper back forcefully at the top of each rep, and return to a fully extended and protracted position.
 
Programming
Single-arm rows can be performed through the entire range of repetitions, from very low (3-5) with extremely heavy weights, all the way up to maximal rep sets of 30 or more. Like any exercise of this nature, many variations of rep and loading schemes can be used, from traditional sets of prescribed reps, to maximal rep sets, to rest-pause sets, etc.
 
Purpose
The single-arm dumbbell row is one of the most basic and accessible but still effective unilateral upper body pulling exercise. Training single arm helps develop and preserve symmetry side to side.
 
Variations
The single-arm row can be done perfectly strictly, or with varying amounts of body English depending on the desired effect. Slow eccentrics and pauses in the top can be added, and straps can be used for extremely heavy or high-rep sets as needed. The support position can also be modified to using only the arm, or to change the angle of the back.