How should we train the triceps?

When training for bigger arms, it is important not to neglect the triceps. At three times the physiological cross-sectional area of the biceps, the triceps brachii are an essential component of the upper arm.

So how can we design a strength training program that will maximize the growth of the triceps? What factors do we need to take into consideration, and how do each of these factors affect the different variables within the training program?

What information do we need?

We can use the research literature to enhance our training programs if we search for information about the gross anatomy, regional anatomy, and internal moment arm lengths of a muscle, in addition to its working sarcomere lengths, and susceptibility to muscle damage. Each of these factors provides information that is useful for different reasons (read more).

• Gross anatomy describes the locations of the attachments of the muscle to the skeleton. Learning the basic anatomy of a muscle helps us figure out suitable exercises, and also helps us see how we might alter them to target different muscles within a group.
• Regional anatomy describes the way in which a muscle divides into several internal regions, and this tells us whether we are going to need multiple exercises to train the muscle.
• The internal moment arm lengths of a muscle determine its leverage on the joint, and therefore its contribution to a joint moment, relative to other agonist muscles. This allows us to see where peak force in an exercise joint range of motion needs to be, to target one muscle within a group (or one region of a muscle). We can alter the point where peak force occurs by our exercise selection and by our choice of external resistance type.
• The working sarcomere lengths describe the lengths of the sarcomeres inside a muscle over its joint angle range of motion. It allows us to see if the muscle can experience (1) active insufficiency (and so will be trained poorly by exercises involving peak forces at very short muscle lengths), and (2) stretch-mediated hypertrophy (and so will be trained more effectively by exercises involving peak forces at very long muscle lengths).
• The susceptibility of a muscle to damage is how easily a muscle is damaged by a workout. It is affected by: (1) muscle fiber type proportion, (2) its level of voluntary activation, and (3) the working sarcomere lengths of its muscle fibers. The amount of muscle damage that a muscle experiences after a workout is the main determinant of the frequency (and volume) we can use for training it, and it also influences our choice of exercises (single-joint vs. multi-joint, single-limb vs. multi-limb, and full vs. partial range of motion).

#1. Anatomy

The triceps brachii is a surprisingly large muscle group that is found on the rear side of the upper arm, and lies adjacent to the humerus (the upper arm bone). In the majority of individuals, this muscle is made up of three heads (the medial head, the lateral head, and the long head), although a fourth head has been observed in some cases.

The three heads of the triceps brachii have different origins. The origin of the medial head is on the medial, posterior side of the humerus, while the origin of the lateral head is on the lateral, posterior side of the humerus (the origin of the medial head is also lower on the humerus than the origin of the lateral head). In contrast, as the only two-joint muscle of the group, the origin of the long head is on the infraglenoid tubercle of the scapula, which is at its most lateral point and on its inferior surface.

Each of the three heads of the triceps brachii insert on the olecranon process of the ulna (a forearm bone), ultimately reaching the same point, although the tendon of insertion of the medial head is deep to the other two heads. The insertions also differ insofar as the medial and lateral heads insert onto the medial and lateral sides of the olecranon, and insofar as the tendon of the lateral head continues onto the lateral and proximal aspect of the ulna.

It is often assumed that all three of the triceps brachii heads are innervated by the radial nerve, which splits into four branches to innervate (1) the long head, (2) the distal medial head, (3) the lateral head, and (4) the proximal medial head. The radial nerve is one terminal branch of the posterior cord of the brachial plexus, while the axillary nerve is another. Nevertheless, some research has found that the long head may be innervated by the axillary nerve, at least in some individuals. Similarly, it is likely that the medial head may be innervated by the ulnar nerve in some individuals. Such differences in innervation between the heads would allow them to be controlled separately from one another.

The triceps brachii is the sole elbow extensor muscle group, making it fairly easy to target. Indeed, the muscle seems quite active in single-joint elbow extension exercises, such as the triceps extension, and also in multi-joint shoulder flexion and elbow extension exercises, such as the bench press. Given that the long head of the triceps brachii is a two-joint muscle, and performs shoulder extension, it is possible that it could be less active during multi-joint shoulder flexion and elbow extension movements like the bench press than the other two heads (since any force produced by the long head could act as an antagonist at the shoulder).

Indeed, the long head does seem to contribute to shoulder extension, which is likely why the triceps brachii overall is recorded as active during the pullover exercise. However, the contribution of the long head to shoulder extension depends upon its leverage relative to the internal moment arm lengths of the other shoulder extensors, and seems to be quite small. Moreover, its internal moment arm length seems to be greatest at high degrees of shoulder elevation (in the pullover position) and smallest in low degrees of shoulder elevation (in the bench press position). Therefore, it seems most likely that the shoulder extension function of the long head will not interfere with its contribution to elbow extension.

Practical implications

In practice, the triceps brachii is a large muscle comprised of three heads. It is the only elbow extensor, and it is likely that all three heads perform this function during both single-joint and multi-joint exercises. The long head of the triceps brachii can also contribute somewhat to shoulder extension, albeit mainly in high degrees of shoulder elevation.

#2. Regional anatomy

There is little research available regarding regions within the triceps brachii heads in humans, as most anatomical studies have focused on the differences between the three heads. Some research has found differences in internal moment arm lengths between the proximal and distal regions of the medial head, and that is about all.

Even so, some long-term strength training studies have found that muscle growth can occur regionally within the triceps brachii, such that growth is greater in the middle and proximal regions after training with the lying triceps extension exercise. Moreover, this exercise caused greater muscle activation in those regions during a workout. This suggests that some regions of the triceps brachii heads may be functionally separate from other regions, although our current understanding of the regional anatomy of these regions is still very limited.

Practical implications

In practice, it seems likely that certain of the triceps brachii heads are formed of separate regions (proximally-to-distally) and that certain exercises may train certain of these regions more effectively than others, due to differences in regional muscle activation. However, we currently have little information about these regions and what causes them to be activated.

#3. Internal moment arm lengths

The triceps brachii comprises two single-joint heads (the medial and lateral heads) and one two-joint head (the long head). All three heads contribute to elbow extension moments, while the long head also contributes to shoulder extension. Also, the contributions of each head to each movement are affected by both elbow and shoulder angles. Even so, the shoulder extension role of the triceps brachii is small, and can be largely ignored (but we cannot ignore the role of shoulder angle in altering elbow extension moment arm lengths).

Effects of shoulder angle

The contributions of the triceps brachii heads to elbow extension are affected by shoulder angle. At low levels of shoulder elevation (arms by the sides), the long head is the main contributor to elbow extension. Yet, as shoulder angle is elevated, the medial and lateral heads of the muscle gradually become more important, although the medial head is the largest contributor when the arm is overhead.

Practically speaking, this suggests that the long head can be best trained with exercises that involve peak force being exerted with the arms by the sides (shoulder extension). In contrast, the medial and lateral heads can be best trained with exercises that involve peak force being exerted with the arms elevated (shoulder flexion). This is in contrast to common bodybuilding wisdom, which suggests training the long head of the triceps brachii in its “stretched position” of shoulder flexion (arm above the head). Ironically, at this shoulder angle, the medial head is by far the greater contributor to the elbow extension movement.

Effects of elbow angle

Many studies have assessed the elbow extension internal moment arm lengths of the triceps brachii, with varying results. Overall, it seems quite likely that triceps brachii elbow extension internal moment arm lengths increase with increasing elbow extension.

A small number of studies have explored the ways in which elbow extension internal moment arm lengths change with elbow joint angle in each of the heads of the triceps brachii. These differences between heads are much smaller than the differences that arise with shoulder angle, but they do exist. One study found that the three heads reached peak internal moment arm lengths at varying points, with the long head reaching its peak at 30 degrees, the lateral head at 20 degrees, and the medial head at 15 degrees, with the result that the medial head displayed the greatest internal moment arm length at full elbow extension. Another study also found that the long head tended to display a smaller elbow extension internal moment arm length as elbow extension approached, albeit the joint angle range of motion measured was not close to full elbow extension. Yet, one study found a different result, with the lateral head displaying a smaller internal moment arm length at full elbow extension than the other two heads.

Consequently, we might be able to marginally increase long head involvement in elbow extension exercises by exerting peak forces when the elbow is more flexed, and marginally increase medial and lateral head involvement in elbow extension by exerting peak forces when the elbow is more extended. Even so, this effect is likely to be quite small relative to the effect of shoulder angle.

Practical implications

In practice, the best way to target the long head of the triceps brachii is with exercises that involve exerting peak elbow extension force with the arms by the sides of the body (shoulder extension), such as with standing triceps pushdowns. The best way to target the medial and lateral heads is with exercises that involve exerting peak elbow extension force with the arms elevated (shoulder flexion), such as with overhead triceps extensions, especially against elastic resistance, since this requires peak force at full elbow extension.

#4. Working sarcomere lengths

The working sarcomere lengths of the triceps brachii do not seem to reach far beyond the plateau region of the length-tension relationship. When measured between 30 and 120 degrees of elbow flexion (where 0 degrees is full elbow extension), the long head of the triceps brachii remains largely on the plateau, while the lateral head works on the plateau and also on the early part of the descending limb.

This suggests that the triceps brachii is quite unlikely to experience active insufficiency when working at short muscle lengths, because it probably does not work on the ascending limb. Therefore, training with partial range of motion exercises could be possible for this muscle, even though its long head is a two-joint muscle.

Additionally, it suggests that only the long head of the triceps is likely to experience any stretch-mediated hypertrophy, and then only when working at its end range of motion. However, the internal moment arm lengths mean that the long head is least active when it is working in this range of motion. This is probably why most studies that have compared the effects of strength training with full and partial ranges of motion in the triceps brachii have reported no beneficial effects of the full range of motion, despite most studies in the quadriceps finding a beneficial effect.

Practical implications

In practice, we can freely make good use of partial range of motion exercise variations when training the triceps brachii, as it will not experience either active insufficiency or stretch-mediated hypertrophy, and will therefore likely respond similarly to training regardless of the range of motion used.

#5. Susceptibility to muscle damage

Research that has studied the effects of a standard workout on a number of muscle groups has found that the triceps takes longer to recover from a standardized workout than many other muscles.

This might be expected, given that the triceps brachii is more fast twitch than many other muscles (and the long head may be more fast twitch than the lateral and medial heads). Also, the triceps brachii reaches high (94–96%) levels of voluntary activation during maximal isometric contractions. This is noteworthy given that the muscle is actually quite large in comparison with many other muscles in the upper body. Even so, the triceps brachii may not be quite as easily damaged as some other muscles, because it operates mostly on the plateau region of the length-tension relationship.

Practical implications

In practice, we should avoid training the triceps brachii (especially the long head) in ways that increase muscle damage, such as by using light weights, high volumes, and larger ranges of motion. We might also choose methods that reduce muscle damage further, such as heavy weights, elastic resistance, and partial ranges of motion. Even so, a lower training frequency may still be helpful.

What is the takeaway?

The triceps brachii comprises three separate heads, which can be trained with different elbow extension exercises. The long head can be targeted with exercises involving the arms by the sides (shoulder extension), such as standing triceps pushdowns. The medial and lateral heads can be targeted with exercises that involve peak contractions while the shoulders are elevated (shoulder flexion), such as overhead triceps extensions. Greater targeting of the medial and lateral heads might be possible by using accommodating resistance to increase the peak forces in full elbow extension.

The triceps brachii is a large, very fast twitch muscle group for which we can achieve very high levels of voluntary activation. Although it works mainly on the plateau of the length-tension relationship, it is therefore easily damaged by training. This indicates that we will want to prioritize training approaches that reduce muscle damage (such as exercises with descending strength curves, partial ranges of motion, or accommodating resistance). We may also want to reduce volume (if we keep training frequency the same as other muscle groups) or train the muscle less frequently (if we keep training volume the same as other muscle groups).

Since the triceps brachii works mainly on the plateau of the length-tension relationship, attempting to achieve stretch-mediated hypertrophy by selecting mainly full range of motion exercises is unlikely to be more effective than partial range of motion equivalents. Given that full ranges of motion cause more muscle damage, and it is important to avoid muscle damage for this muscle group, partial range of motion variations may be the best option.