You’ve probably seen the guys in the gym obsessing over the "horseshoe" look. They’re hitting heavy ropes, doing overhead extensions, and flared-out pushdowns like their lives depend on it. They want that lateral head pop. Maybe they’re chasing the long head for sheer mass. But there is a third player. A hidden workhorse.
The medial head tricep workout is basically the unsung hero of elbow stability and lockout power. If your triceps look thick from the side but disappear when you lock out a bench press, you’ve got a medial head problem. Honestly, it’s the deepest part of the muscle. It sits underneath the long head, acting like a structural foundation. You can’t see it as easily as the outer "sweep," but it provides the "girth" that makes an arm look dense rather than just wide.
Most lifters think they’re hitting it by accident. They aren't. While the triceps brachii functions as a single unit to extend the elbow, the medial head is uniquely active during the final degrees of extension. It’s a "finisher" muscle. If you’re cheating your range of motion or bouncing off the bottom of a rep, you are effectively deleting the medial head from the conversation.
Why the Medial Head is the "Secret" to Real Arm Thickness
Look at the anatomy. The triceps has three heads. The long head originates at the scapula. The lateral head starts on the humerus. But the medial head? It’s deep. It’s mostly covered by the other two, yet it has a broad attachment point along the back of the humerus. Research, including classic EMG studies by the likes of Dr. Boeckh-Behrens and Buskies, suggests that while all three heads fire during extension, the medial head is the primary stabilizer. It’s the first one to kick in and the last one to let go during a heavy press.
If you have elbow pain, listen up. A weak medial head is often the culprit behind "scratchy" elbows. Because it attaches so close to the elbow joint, it provides a localized pull that keeps the joint tracking correctly. Think of it like the VMO (the teardrop muscle) of the arm. Without it, things get sloppy.
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Most people fail here because they treat the triceps like a single block of meat. They do three sets of ten on the cable machine and call it a day. But the medial head responds best to specific grip widths and hand positions. Specifically, a reverse grip (supinated) or a very narrow neutral grip forces the medial head to take over because it minimizes the leverage of the massive long head.
The Best Exercises for a Medial Head Tricep Workout
Forget the fancy machines for a second. Let's talk about the Reverse Grip Cable Pushdown. This is the gold standard. When you flip your palms up, you aren't actually changing the "origin" of the muscle—muscles don't know which way your wrist is turned—but you are changing the mechanics of the pull. By using a supinated grip, you naturally tuck your elbows closer to your ribs. This alignment puts the medial head in the direct line of force.
You don't need heavy weight here. In fact, if you go too heavy, your wrists will give out before your triceps do. It’s about the squeeze. Use a straight bar or an EZ-bar attachment. Keep your shoulders pinned back. Drive the bar down until your arms are dead straight. Hold it for a second. That burn in the lower, inner part of your arm? That’s it.
The Diamond Push-Up Factor
Diamond push-ups are brutal. They’re also one of the most effective bodyweight moves for the medial head. A study published by the American Council on Exercise (ACE) actually ranked the triangle push-up as the #1 exercise for overall triceps activation. Why? Because the narrow hand placement shifts the load away from the pecs and onto the triceps, specifically demanding a hard lockout.
Here is the trick: don't just go up and down. At the top of the rep, try to "screw" your hands into the floor. This creates external rotation tension. It forces the medial head to fire even harder to maintain that rigid lockout.
JM Presses: The Powerlifter’s Choice
If you want the medial head tricep workout that the strongest guys in the world use, you do the JM Press. Named after JM Blakely, this move is a hybrid between a close-grip bench press and a skull crusher. You lower the bar toward your throat or upper chest, letting the elbows flare slightly forward, then drive up. It puts an incredible amount of tension on the triceps tendon and the medial head.
- Start with just the bar.
- Keep the movement tight and controlled.
- Stop an inch before your chest.
- Explode up, but don't bounce.
Common Mistakes That Kill Your Gains
Stop flailing. Seriously. The biggest mistake in any medial head tricep workout is "elbow drift." When your elbows move forward and backward during a pushdown, you’re using your lats and shoulders to move the weight. The triceps only move the forearm. If your upper arm is moving, you’re doing a lat pulldown, not a tricep extension. Glue those elbows to your sides. Imagine there is a rod running through your ribs and through both elbows.
Range of motion is the second killer. People love to do "half reps" with heavy weight to ego lift. But the medial head is most active at the very end of the movement—the lockout. If you aren't reaching full extension, you are literally missing the part of the rep where the medial head does its best work.
Also, watch your grip. Don't death-grip the bar. It sounds counterintuitive, but squeezing too hard can sometimes lead to forearm fatigue that masks the mind-muscle connection with the triceps. Try using a "suicide grip" (thumbless) on pushdowns if you're experienced. It helps align the force through the heel of the palm, which lines up better with the ulna and the triceps attachment.
Programming for Medial Head Growth
You don't need a dedicated "Medial Head Day." That would be overkill and, frankly, kind of boring. Instead, sprinkle these movements into your existing push or arm days.
A solid approach is the High-Low Strategy.
Start your workout with a heavy compound move like the JM Press or Close Grip Bench Press for 5-8 reps. This builds the foundational strength. Then, move into "isolation" work. This is where the reverse grip pushdowns or diamond push-ups come in. For these, aim for higher reps—anywhere from 12 to 20. The medial head has a high percentage of slow-twitch fibers compared to the lateral head, so it thrives under metabolic stress (the pump).
Try this "Finisher" next time you're at the gym:
Perform 15 Reverse Grip Pushdowns, immediately followed by as many Diamond Push-ups as you can do. Rest 60 seconds. Repeat 3 times. Your arms will feel like they’re going to explode, but that’s the blood volume you need to trigger hypertrophy in those deep muscle layers.
The Role of Genetics and Bone Structure
We have to be honest here. Some people have "long" triceps and some have "short" ones. This is determined by your tendon insertions. If your triceps muscle belly stops high up on your arm, leaving a large gap above the elbow, you’ll have a harder time "filling out" that lower area.
However, even with "high" insertions, building the medial head creates a thicker base. It pushes the other two heads out. It’s like putting a bigger engine block in a car; even if the hood is the same size, the whole front end looks more muscular. Don't get discouraged if you don't see immediate "pop." This is a muscle of density, not just shape.
Real World Results: The Case for Consistency
Look at old-school bodybuilders from the 70s. They didn't have the fancy ISO-lateral machines we have now. They did a lot of dips and a lot of narrow pressing. Their triceps had a "thick" look from every angle because they weren't just focusing on the "sweep."
The medial head is also vital for overhead pressing. If you’re a weightlifter or a Crossfitter, a strong medial head prevents your elbows from "caving" or shaking when you have a heavy load over your head. It’s the stabilizer that keeps the joint locked in place under duress. If your overhead press has plateaued, stop doing more shoulder presses and start hitting your medial triceps.
Actionable Steps for Your Next Session
Don't just read this and go back to your old routine. Change one thing today.
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- Swap your grip: On your last tricep exercise of the day, flip your hands over. Use that supinated grip. Feel the difference in where the tension sits.
- Exaggerate the lockout: On every single rep of every tricep move, hold the bottom position for a full 2-second count. Squeeze so hard you feel a cramp.
- Add "Close Grip" variations: If you usually bench press with a wide grip, move your hands in so your index fingers are on the smooth part of the bar. It’s a game changer for the deep tricep fibers.
- Track your progress: Don't just go by the mirror. Track your strength on the JM Press or the number of diamond push-ups you can do. As these numbers go up, the thickness of your arm will follow.
The medial head isn't flashy. It doesn't get the "peak" that the long head gets. But it is the difference between an arm that looks "okay" and an arm that looks like it was carved out of granite. Put in the work on the deep fibers, and the rest of the arm will reap the rewards. Focus on the squeeze, master the reverse grip, and stop skipping the lockout. Your elbows, and your t-shirt sleeves, will thank you.
Next Steps for Success:
Start your next upper body workout with 3 sets of 15 Reverse Grip Cable Pushdowns using a light weight to pre-exhaust the medial head. Focus entirely on the bottom third of the movement where the contraction is most intense. Follow this with your primary heavy pressing movement to see if you feel a more stable, powerful lockout. This simple "pre-activation" technique can bridge the gap between a standard workout and one that actually targets the deep medial fibers.