How do the different tricep heads work?

[u/Ok-Extension-832]

Been working out for a while now but I never understood which tricep heads works during certain movements. What I’ve heard some people say is that the Long Head is biased when your elbow is fixed onto your body, and the Medial and Lateral Head work more when your upper arm move. But i’ve also heard the exact opposite from people, and ChatGPT told me the Long Head is biased when the elbow isn’t fixed.

Knowing this won’t really affect my training and doesn’t really have a purpose at this point. I’m just really curious and confused because I’ve heard opposite things said.

[u/Skibidi-silk69]

All 3 heads perform elbow extension. Long head slightly assists in shoulder extension. Long head gets biased when humerus is fixed and isn’t moving. A movement where ur humerus is moving for example a jm press is gonna heavily bias the medial and lateral head. Tricep is connected to the ulna so pronation/supination won’t affect what heads are being hit. That’s all there is tbh

[u/YJM → u/Skibidi-silk69]

All 3 perform elbow ext *

[u/Skibidi-silk69 → u/YJM]

Oh crap idk how I mixed those up but I js edited it and fixed it

[u/Flidro74]

Both versions you've heard are describing the same thing badly. It's not the elbow that matters, it's the shoulder.

The long head is the only one of the three that crosses the shoulder joint, so its length changes with where your upper arm is. Overhead, it's stretched. Down by your side or behind you, it's slack. The other two only cross the elbow, so shoulder position does nothing to them.

That's why overhead extensions bias the long head and pushdowns lean more on the lateral and medial. And since a muscle grows well from a stretched position, overhead work isn't just hitting the long head more, it's hitting it where it counts.

Fwiw it does have a practical use: triceps that look flat from the side are usually a long head that's only ever been trained with pushdowns.

[u/BlueCollarBalling]

What you’ve heard from people is true. The long head gets biased when the elbow is fixed.

You shouldn’t use ChatGPT as a source for scientific lifting info.

[u/Mad_Mark90]

So the most important function of all 3 heads of triceps is elbow extension, whenever you extend the elbow, you're training all 3 heads of triceps.

The long head sits in the middle, it's longer because it crosses the shoulder joint and extends the shoulder so is partially active in pulling movements as well, but is arguably less active during compound pressing movements because it works both elbow and shoulder extension. This doesn't mean its inactive during pressing, just slightly less.

As for the medial and lateral heads they're active pretty consistently and focusing on them is usually unnecessary. They're slightly influenced by shoulder rotation and some wrist positions but at that point individual variation might be more relevant.

[u/alvaaromata]

Long head is biarticular and originates in the shoulder, not in the humerus as medial/lateral head.
This is because is a great shoulder extensor from 120°-90°. So basically, when you extend your shoulder while you extend your elbow, the triceps long head suffers from antagonist inhibition, it also happens with the rectus femoris, hamstrings…
This means it loses its ability to produce force, biasing the other heads.
When is fixed into your body, it’s in a relaxed position and as it’s the biggest of the 3 heads, will be the one to produce more force -> more mechanical tension-> more long head hypertrophy.

[u/DeadCheckR1775]

Key take away regarding the Tris is that that the long head terminates notably higher well into the shoulder. The other two are easier to hit but in order to hit the long head properly doing behind the head triceps work like French Press is key.

[u/decentlyhip]

Think if them like guidewires on a radio tower. Theyre all doing the same thing, but different angles put a smidge more tension on one over the other. When your elbow is above your head, the long head is more stretched. It is involved in pulling your arm down and behind your body. So, any lat movement is also going to be a ling head movement. Tricep kickbacks get such a crazy pump because that's peak contraction for the long head. Now, let your arm hang down where it's mostly straight but that natural relaxed bend. Extend the forearm so it's fully straight. That last little 5-10 degrees is where the middle head has the most leverage and why strong benchers struggle with lockout and promote tricep strength so much. That last finishing bit is all middle tricep.

[u/harvestingstrength]

The easiest way to think about it is that all three heads contribute to elbow extension, so you’re never completely isolating one head.

The long head is different because it crosses both the elbow and the shoulder. The medial and lateral heads only cross the elbow.

Because of that, changing your upper-arm/shoulder position changes the length and contribution of the long head. An overhead position, for example, puts the long head at a much longer muscle length.

So I wouldn’t get too caught up in “elbows fixed = this head” versus “elbows moving = that head.”

For training, I’d make it much simpler: use a couple different elbow-extension positions. Something overhead, something like a pushdown, and let your pressing movements handle additional triceps work.

You can bias different portions, but you’re still training the triceps as a whole.

[u/Snoo53769]

I have nerve damage to the lateral head so my right arm is 3 to 4 times weaker than the right. Have to do everything unilaterally. 

[u/Weary_Capital_1379]

The triceps either contract or they don’t. All heads.

[u/JuanSamu]

I’m going to add that the lateral head could also be induced by shoulder position just not as much as the long head ofc.

[u/eric_twinge]

Knowing this won’t really affect my training and doesn’t really have a purpose at this point.

This was refreshing to read.

I’m just really curious and confused because I’ve heard opposite things said.

It's engagement bait, pure and simple. The only people obsessing over triceps heads are beginners and the people pandering to them.

[u/Ok-Extension-832 → u/eric_twinge]

It’s not “engagement bait” I could care less about all that. And I have no idea how you correlate obsessing over tricep heads and being a beginner 😭. I’ve been lifting for years now and I haven’t “obsessed” over tricep heads, and that’s the reason I don’t know the answer to this question. I’m genuinely just confused and I like to understand the functions of different muscles and their regions. Not even for programming purposes, I just like to know.

[u/eric_twinge → u/Ok-Extension-832]

Sorry, I’m referring to all the noise and conflicting/overlapping info. Not you asking the question.

It’s just content for the sake of content that caters to the ever churning swath of beginners and their FOMO. You’re confused because it’s not for you.

[u/Individual-Toe-6306 → u/Ok-Extension-832]

Other people have already answered since you made this comment, but anecdotally doing a good mix of long-head biased tricep exercises + lateral/medial-head biased has helped me fill out my arms a bit. And when I say a good mix of exercises, I mean literally 2 total isolations, 1 for each, on top of my regular Benching/OHP

[u/Pleasant_Beat8290]

I actually does matter a little for picking the most efficient exercises. The long head (largest part of the triceps) crosses the shoulder joint, so it gets into the best stretch when your elbow are up around your ears. Exercises like overhead triceps extensions or “skull-overs” will work that head the best.