Support yourself with one knee and hand on a bench with the trunk horizontal. Hold a dumbbell in the free hand with the palm facing inward. Keep the upper arm horizontal and against your side, and extend the elbow completely, then return to the start under control.
 
Purpose
The tricep kickback is a simple and accessible tricep isolation exercise that emphasizes the lateral head. It can be used as a substitute for a neutral grip cable pushdown when there is no access to a cable stack machine.
 
Programming
Generally sets of 8-15 reps are appropriate.
 
Variations
The hand can be pronated as the elbow is extended, although this can get tricky because the dumbbell will contact the hip if the arm is close to the body. The straight arm can also be lifted at the top to train that function of the tricep long head.