Machine Triceps Extensions

Adjust the seat height so that the back part of your arms lay flat against the pad and your elbows line up with the axis of rotation of the machine; your shoulders should be at equal height to the elbows.
 
Adjust the back pad so that your back is comfortably supported in an upright position and grab the handles so that your palms face each other with thumbs facing you.
 
Press the handles down and away, keeping the back of your upper arms flat against the pad, until your arms are straight.
 
Reverse the movement and return to the starting position.
 
The entire motion should be performed in a smooth, controlled manner that lasts about 3 seconds with the downward movement no faster than the upward.