A tricep extension is a weight-training exercise that targets the triceps brachii. Often simply termed 'the triceps,' this medium-sized muscle is located at the back of the upper arm and is primarily responsible for elbow extension. The tricep extension typically involves any movement that extends the elbow through a full range of motion against a weighted resistance. The triceps itself is a three-headed muscle and, when well developed, contributes significantly to arm circumference.
Powerful for its size, the triceps is capable of moving a great deal of weight. It is precisely because of this power that care should be taken when performing the tricep extension. The nature of the movement itself tends to open up the elbow joint. Poor form, too much weight on the barbell, or failure to warm up can all lead to elbow injury during a tricep extension. While heavy loads are generally safe for use with compound triceps exercises, such as close-grip bench presses, this particular movement is safest when using a lighter weight for high repetitions.
A tricep extension is usually performed sitting on a chair or weight bench. As the starting position, a weighted barbell is held over the head, with arms fully extended. Keeping the elbows and upper arms stationary, the barbell is lowered as far as the range of motion will comfortably allow. The barbell should then be returned to the starting position in a slow and controlled manner. Any swinging of the torso or upper arms to assist the movement indicates that the barbell may be too heavy, in which case a lighter weight should be used.
Variations on this movement include substituting a dumbbell for a barbell, or performing the exercise in a standing or lying position. A lying tricep extension, also known as a skull crusher, begins with lying prone on a weight bench with the arms extended perpendicular to the floor. The hands should grasp the barbell in a narrow, overhand grip. The weight is lowered almost to the forehead, then returned to the starting position. This position will often allow more weight to be handled than a seated or standing extension, but also carries with it a slightly increased risk of injury.
The triceps kickback, or dumbbell kickback, is a variation of the tricep extension that works each arm singly. With one knee supporting the body on a weight bench, the lifter bends at the hips to bring the torso parallel to the floor. The arm opposite the supporting knee grasps a dumbbell and, with the upper arm in line with the body, moves from a 90° angle to a full extension, and back again. As this variation typically involves a lighter weight moved over an increased range of motion, it is often a favorite for adding shape and definition rather than extra mass.