The chainsaw row is a variation of the 1-arm dumbbell row that changes the body position and uses more of the body to move the weight.
With a wide stance, bend forward and toward one leg to rest your forearm on one knee. Start with a dumbbell in your free hand and the arm extended completely and shoulder blade protracted so the weight is just off the floor. Row the dumbbell up by retracting the shoulder blade and pulling the elbow as high as possible—allow the weight to trail behind the elbow. Allow the trunk to rotate somewhat to gain more height and squeeze your upper back forcefully at the top of each rep—use the whole body to move the weight as if you’re trying to start a stubborn chainsaw. Return to a fully extended and protracted position while rotating the trunk back to its original orientation.
Chainsaw 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. This row variation allows more weight to be used than a traditional dumbbell row, and allows higher reps at a given weight because more of the body is being use to create more speed.
The chainsaw 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. Any weighted implement can be substituted for a dumbbell.