Lying Barbell Triceps Extensions aka Skull Crushers

By Stephen E. Alway, Ph.D., FACSM

The triceps brachii muscle has three heads to it. The long head of the triceps brachii is the “inner head.” It begins on the scapula bone (shoulder blade) just inferior to (below) the head of the humerus bone at the shoulder joint.1 The long head of the triceps extends down to the back of the arm where it forms a tendon and joins the tendons from the other triceps heads to form a common triceps tendon at the elbow. The triceps tendon crosses the elbow joint to connect to the posterior side of the ulna bone of the forearm near the elbow.1 All three heads of the triceps brachii extend the forearm. However, the long head can also act to extend the shoulder (pull the arm to the rear of the body), because the long head crosses the shoulder and attaches to the scapula. Both of these functions of the long head are activated by lying barbell triceps extensions.

The lateral head of the triceps brachii is anchored to the posterior part of the humerus bone of the upper arm, partway towards the shoulder joint.1 The lateral head of the triceps extends the forearm at the elbow joint (i.e., straightens the elbow joint). The medial head of the triceps brachii resides between and the other two heads of the triceps brachii. It begins along on the upper posterior part of the humerus bone and its fibers run down the arm and attach to the common triceps tendon to insert on the ulna bone. The medial head shares duties for extension of the forearm with the other heads of the triceps.1

Lying Barbell Triceps Extensions aka Skull Crushers

Lying Barbell Triceps Extensions

This exercise is safe, effective and excellent for hitting all three heads of the triceps on each repetition.

1. Place a light barbell across the end of a flat bench. An EZ bar (as illustrated) is slightly bent and you may prefer it to the straight bar, as it is easier on the wrists. Lie on the bench and grip the bar behind your head with your hands about 4 inches apart and with the palms facing the ceiling. You can place both feet on the floor but if you have had any lower back problems, it is best to put both feet on the bench.

2. Lift the bar from the bench by extending the elbows until the bar is directly over your eyes.

3. Do not pause but immediately lower the bar towards your forehead. Next, move your arms and elbows back just enough to allow the bar to clear your forehead and pass just slightly behind your head. Keep the elbows pointing towards the ceiling throughout the lift.

4. Stop when the back of your hands fall just behind (or almost touch) your head. The weight should be lowered slowly (3-4 seconds).

5. Do not rest, but immediately extend your elbows and be careful to lift the bar to miss your head as it moves upwards. Return the bar over your eyes until the elbows are almost straight, and then repeat the downward movement back towards your head.

Lying Barbell Triceps Extensions aka Skull Crushers

Your ability to control the barbell is essential, and therefore it is critical that you use a light or empty barbell to start with until you get the feel of the exercise. After a week or two you can add a little weight to the bar, but keep the barbell light enough so that you can fully control it. Generally, the smaller and weaker triceps muscle fibers will be recruited early in the set. As the triceps begins to fatigue, the larger and stronger muscle fibers of the long head come on board to keep the bar moving. The fibers in the long head of the triceps will be recruited especially well when the weights get heavier or when the other heads become very fatigued.3 Lighter or medium loads for 12 or more repetitions will preferentially activate the medial and lateral heads of the triceps.3

Make sure you warm up your elbows before getting into the swing of this exercise. Joint pain from improper exercise form or hitting the weights without a proper warm-up can be easily avoided with a suitable warm-up and attention to exercise form. You can expect some muscle discomfort that will occur from the exercise-induced metabolites and minimal blood flow4 during your set. However, this type of muscle discomfort does not mean that you can give up early in your set, because this pain means that you are working hard enough to make superb advancements in your triceps shape and tone.

1. Moore, K.L. and A.F. Dalley. Clinically orientated Anatomy, Fourth Edition. Lippinot, Williams & Wilkins, 1999; pp. 720-781
2. Serrau V, Driss T, Vandewalle H et al: Muscle activation of the elbow flexor and extensor muscles during self-resistance exercises: comparison of unilateral maximal cocontraction and bilateral self-resistance. J Strength Cond Res 2012;26:2468-2477.
3. Wakahara T, Miyamoto N, Sugisaki N et al: Association between regional differences in muscle activation in one session of resistance exercise and in muscle hypertrophy after resistance training. Eur J Appl Physiol 2012;112:1569-1576.
4. Yasuda T, Fukumura K, Fukuda T et al: Effects of low-intensity, elastic band resistance exercise combined with blood flow restriction on muscle activation. Scand J Med Sci Sports 2012; Jun 27. doi: 10.1111/j.1600-0838.2012.01489.x. [Epub ahead of print].

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