Single Arm Tricep Extension With Dumbbell
Isolate the tricep by lying flat on a bench. Raise a single dumbbell over your shoulder so your whole arm is vertical. Keep the upper arm locked, hinge only at the elbow to bring the dumbbell towards your body, with a hammer grip. Stretch at the bottom, slowly up, and squeeze at the top. You can use the other hand to check your arm is staying locked in position.
