The triceps press machine facilitates the isolation exercise focused on of the muscles on the back of the upper arm. This muscle, called the triceps, has three heads: the long head, the lateral head, and the medial head. The three heads work together to extend the forearm at the elbow joint.
The triceps press is a good exercise to lead off a triceps workout because it facilitates greater loads to be used in relation to some of the popular isolated triceps exercises, due to it being a compound movement, but it is also a great finisher.