Triceps extension

Key points

The triceps brachii, the three-headed muscle on the back of the upper arm, and the anconeus are the muscles that straighten the elbow^1,2.
In one 12-week study of 21 adults, the arm trained overhead grew more triceps volume than the arm trained at the side³.
A second, 6-week study, in untrained young women, found similar long head growth either way⁴. A review notes that the two trials disagree⁴.
In 21 resistance-trained men, overhead and lying dumbbell extensions gave similar patterns of activity in the long and lateral heads⁵.
In one 8-week trial in 55 untrained young women, triceps thickened in arms trained at one load and about twice as much with progressive overload⁶.
The tendon ruptures (tears) on this page reported during the exercise come from case reports, each on a single patient^7,8.

Movement

What the elbow and shoulder do

The muscles that straighten the forearm at the elbow are the triceps brachii and the anconeus². The anconeus is a small muscle at the back of the elbow, and it adds a little to the triceps’ work⁹. The triceps has three heads: long, lateral and medial¹. They have long been described as joining into one shared attachment on the olecranon, the bony point of the elbow¹⁰.

The long head starts on the scapula (shoulder blade), while the lateral and medial heads start on the humerus (upper arm bone)¹. Of the three heads, only the long head crosses two joints¹¹. The triceps also works in shoulder extension, moving the arm backward, alongside several other muscles⁹. The long head is stretched further with the arm overhead than with the arm at the side³.

The versions studies have used

The studies on this page tested the exercise in several forms^3,5,12:

Cable elbow extensions with one arm overhead and the other arm at the side³.
Overhead and lying dumbbell elbow extensions⁵.
Barbell lying elbow extensions through a middle range of 45 to 90 degrees, or a full range of 0 to 120 degrees^4,13.
Free-weight lying triceps extensions¹⁴.
Standing cable pushdowns with a standard handle or a ball handle¹².
Overhead cable extensions through part of the range, from 60 to 110 degrees of elbow bend¹⁵.

What it loads

The medial head is described as working in every form of elbow straightening⁹. The long and lateral heads join in mainly when the elbow straightens against resistance⁹.

One study had ten healthy people straighten the elbow with the arm at five shoulder angles¹¹. It combined electromyography (EMG), which picks up a muscle’s electrical signals, with a computer model¹¹. Its findings, head by head:

Head	What the study found
Long head	More modelled force and activation than the other heads with the arm at the side¹¹
Medial head	More modelled force with the arm raised 90 degrees or higher¹¹
Medial head	Most modelled force with the elbow bent 85 to 110 degrees, whatever the shoulder position¹¹
All three heads	Higher modelled force and activation with the elbow bent past 90 degrees¹¹

In the same model, the long head lengthened as the arm was raised forward¹¹. The lateral and medial heads stayed the same length¹¹.

A different study used a dynamometer, a machine that measures turning force, in 18 people¹⁶. Their triceps was made to contract with electrical stimulation¹⁶. The turning force it produced at the shoulder rose significantly between shoulder angles of 0 and 80 degrees¹⁶. The authors suggest its moment arm, or leverage, lengthened¹⁶.

Overhead and lying dumbbell extensions

One study recorded the long and lateral heads in 21 resistance-trained men⁵. Overhead and lying dumbbell extensions gave similar patterns of activity⁵. In both, the eccentric phase, lowering the weight, drew less activity than the concentric phase, lifting it⁵. While lifting, activity was higher in the first and middle thirds of the movement than in the last third⁵. That held for both heads in the overhead version, but only for the lateral head in the lying version⁵.

Pushdowns: fatigue and handles

In 25 people doing triceps pushdowns until they could not go on, surface EMG suggested the three heads did not act together¹⁷. The rate of fatigue rose with heavier loads and faster speeds, and time to failure fell¹⁷. The long head had the highest average rate of fatigue and the medial head the lowest¹⁷. Even so, the authors describe the three heads’ rates as comparable¹⁷.

Handle type changed activity patterns in forearm muscles, not in the triceps, in one study of standing pushdowns¹². Triceps activity did not differ between a standard handle and two ball-handle grips¹². The extensor digitorum, a forearm muscle that straightens the fingers, was most active with a ball handle¹². In that grip, the cable passed between the index and middle fingers¹².

The shoulder

The front of the deltoid, the rounded muscle that caps the shoulder, was measured in trained young men¹⁴. They did free-weight lying triceps extensions at an 8-repetition maximum, the heaviest load they could lift eight times¹⁴. Activity was measured against a maximal voluntary isometric contraction, the muscle’s hardest effort while the joint stays still¹⁴. Front deltoid activity was 53.89% of that when the exercise came last in the session¹⁴. It was 34.32% when the exercise came first¹⁴.

The distal triceps tendon

The distal triceps tendon joins the triceps to the olecranon¹⁰. In five pair-matched cadaver arms, from bodies donated for study, the triceps attached to the olecranon in three distinct areas¹⁰. They were the back of the joint capsule, a deep muscle part from the medial head, and a surface tendon from the other two¹⁰. The joint capsule is the sleeve of tough tissue that encloses a joint.

Injuries reported with triceps extension

The tendon injuries on this page reported during the exercise itself come from case reports^7,8. Each describes one person:

A healthy 52-year-old non-professional bodybuilder’s triceps tendon tore completely at the olecranon during a single-arm triceps extension, without any blow or fall⁷. He had had mild elbow discomfort with exercise in the two months before⁷.
The authors of that report put the rupture down to chronic tendinopathy related to overload⁷. Tendinopathy is local pain in a tendon that comes with activities that load it. The weight was moderate⁷.
A 53-year-old recreational bodybuilder had a full-thickness tear, right through the triceps tendon, while doing triceps extensions in the gym⁸. The tendon had pulled back about 5 cm from the olecranon⁸.

A systematic review pooled athletes whose distal triceps tendon ruptures were repaired¹⁸. Where the sport was recorded, weightlifting was the most common, at 40.7%, followed by American football at 26.6%¹⁸. The same review reports that, in resistance training, they mostly happen while lowering the weight in bench or overhead pressing, under eccentric load¹⁸. In a retrospective review of 21 ruptures in 19 professional American football players, the most common cause was an eccentric load on a contracting triceps¹⁹. Another review reports that up to a third of people with a rupture may have had long-standing pain at the back of the elbow beforehand²⁰.

How the body adapts

The arm overhead compared with the arm at the side

In one study, 21 adults trained cable elbow extensions for 12 weeks, one arm overhead and the other at the side³. MRI, a scan that shows muscle in detail, measured muscle volume before and after³. The overhead arm grew more in each part measured³:

Volume gain, arm overhead (%). Bars start at zero; the table below gives each value with its source.

Part of the triceps	Volume gain, arm overhead	Volume gain, arm at the side
Long head	28.5%³	19.6%³
Lateral and medial heads	14.6%³	10.5%³
Whole triceps	19.9%³	13.9%³

The overhead arm always lifted 34 to 39% less weight, yet its one-repetition maximum rose by a similar percentage in both arms³. That is the heaviest load a person can lift once. The authors describe the lighter loads as lower mechanical stress on muscles and joints³.

A review calls the extra growth in the lateral and medial heads unexpected, since those heads cross only the elbow⁴. It suggests that factors other than muscle length may have played a part⁴.

A second study found no difference

A review notes that two trials comparing the arm overhead with the arm at the side disagree⁴. A review summarises the second, a 6-week study of untrained young women⁴. The study compared pushdowns with overhead extensions⁴. Muscle thickness, measured from the muscle’s surface to the bone, rose by similar amounts in the long head with both exercises⁴.

A systematic review describes a study comparing the two, with the pushdown arm at the side and the overhead arm raised fully²¹. Growth was similar between arms²¹. Fascicle length, the length of the bundles of fibres in the muscle, rose only in the pushdown arm, at one site²¹. Overhead work grew the long head slightly more near the elbow, and pushdowns more near the shoulder, but neither difference was statistically significant²¹.

A narrative review offers three possible reasons for the disagreement⁴. The trials measured muscle differently: volume in one, thickness and cross-sectional area in the other⁴. Cross-sectional area is the size of a slice cut straight across the muscle. They ran for 12 and 6 weeks, and the exercise set-up differed⁴.

Range of motion: findings differ

Two triceps studies of partial range found different results^4,13,22. They used different partial ranges: a middle range in one and the stretched end in the other^4,13,22. Range of motion is how far a joint moves during a movement.

Barbell lying extensions: in trained men over 8 weeks, a middle range of 45 to 90 degrees grew triceps cross-sectional area more than full range^4,13.
An 8-week upper-body programme that included overhead dumbbell extensions and pushdowns: 30 trained people did it²². One side of the body did partial reps at the stretched end, and the other did full reps²². Partial reps gave elbow extensor thickness gains similar to full reps²².

A systematic review found only two upper-body studies of range and growth²³. The elbow extension study, in 44 resistance-trained men, favoured the partial range²³. The other upper-body study found a modest edge for the full range, 9.7% against 7.8%²³. That difference was not statistically significant²³. The same review, of six studies, found upper-limb research on range of motion and growth limited and conflicting²³.

A sport skill

In a randomised trial of 30 recreational basketball players, one group trained overhead cable extensions for 4 weeks through part of the range¹⁵. Another group trained through the full range, and a third was a control group¹⁵. A three-point shooting test improved in both training groups¹⁵. After training, only the partial-range group scored significantly differently from the control group, and the two training groups did not differ significantly from each other¹⁵.

Progressive overload

A 2026 position stand describes progressive overload as the need to increase the stimulus placed on the muscle throughout a training programme²⁴.

Rising load against one load

One trial tested progression directly, in 55 untrained young women⁶. Each woman’s arms were randomly assigned to progressive overload, an unchanging load, or no exercise⁶. After 8 weeks of elbow extension training, the triceps had thickened under both training conditions⁶. Arms given progressive overload grew about twice as much, roughly 23% against 12%⁶.

The authors concluded that growth appears more pronounced with progression⁶. They also found an unchanging load still enough for growth in these women⁶. Whether it keeps working over longer periods, they wrote, is an open question⁶.

How other trials set the load

Four other trials report how they set the load^15,22,25,26:

Who trained, and the exercise	How the load was set	What was found
30 healthy men, dumbbell lying triceps extension, 3 days a week for 6 weeks	30% of one-repetition maximum, retested every 2 weeks so the load could be readjusted²⁵	In the group trained without heat, no significant change in one-repetition maximum or triceps thickness²⁵
22 healthy men with at least 6 months of training, cable pushdowns and biceps curls, twice a week for 7 weeks	30% of one-repetition maximum with blood flow restriction, the cuff pressure raised over the sessions²⁶	Pushdown one-repetition maximum rose 28.5%, and 29.5% in a group training at 70% of one-repetition maximum²⁶
30 recreational basketball players, overhead cable extensions	67% of a one-repetition maximum calculated before training, with 2-minute rests and two sessions a week¹⁵	Shooting results are under “A sport skill” above¹⁵
30 resistance-trained people, an upper-body programme with overhead dumbbell extensions and pushdowns, twice a week for 8 weeks	Every set taken until another full repetition could not be done, with the load adjusted set by set to stay in the target repetitions²²	The trial compared ranges of motion, under “Range of motion” above²²

In the lying extension trial, a second group had a hot pack on the triceps for 20 minutes before training²⁵. That group gained significantly in both measures²⁵. The pushdown trial used blood flow restriction, exercise with a cuff around the limb that partly limits its blood flow²⁶. Both of its groups also did biceps curls, so the strength gains come from a two-exercise programme²⁶.

Connections

The muscles it works

The triceps brachii, whose heads were measured in elbow straightening studies^11,17.
The anconeus, a small muscle that helps the triceps straighten the elbow⁹.
The front of the deltoid, which was active in free-weight lying extensions¹⁴.
The extensor digitorum, a forearm muscle whose activity changed with pushdown handle type¹².

The tendon it loads

The distal triceps tendon is where all three heads have long been described as joining, on the olecranon¹⁰. The case reports above describe it tearing during the exercise^7,8.

Pressing exercises

In a computer model of the bench press and overhead press, the elbow extensors did little early in the lift²⁷. They became the main muscles near full extension²⁷.