Every Muscle Insertion Explained Part 2 (Good vs Bad Genetics)

Ajouté : 2026-05-05

[00:00:00]Shoulders. Broad shoulders aren't built in the gym. They're built before you ever touch a weight. Clavicle width matters. A wider collarbone creates a broader frame, but that's bone structure, a different conversation.

[00:00:12]Here, the variable is the muscle itself.

[00:00:14]The deltoid has three heads, front, side, rear, but only one determines how wide you look from across the room. The middle head, where it attaches to the upper arm, the humerus, that's what changes everything. A low insertion runs the muscle further down the arm. When it develops, it can create a rounder, fuller cap, though the final shape depends on the muscle belly as well.

[00:00:36]Generally wider from every angle, but never guaranteed. A high insertion sits closer to the top, shorter muscle. Still impressive, but the width has a ceiling, and that ceiling is low. You can't lateral raise your way out of a high insertion. The exercises develop what's there. They don't move where it attaches. Two guys, same gym, same years, same effort. One looks like a wall, the other just looks like he lifts. Nobody talks about why. Traps.

[00:01:03]Size is the first thing people notice about traps, but origin is what decides whether they look good or just big. The trapezius runs from the base of the skull down to the mid spine. The upper portion is what everyone sees, the part that climbs the neck. A low origin, further from the skull, gives the muscle more room. The traps sit further down the frame, the neck breathes, the shoulders read wider, the whole upper body looks more complete. From the front, the athlete looks athletic, structured, like the body was designed to carry muscle. A high origin climbs closer to the skull, and when that muscle develops, it takes the neck with it. The mass bunches upward, compressing the space between jaw and shoulder, until there's almost nothing left. The athlete looks thick, powerfully even, but the neck is gone. What's left looks like a small head placed directly on top of a massive body, like the proportions don't belong to the same person. And here's what makes it complicated.

[00:02:03]Heavily developed traps with a high origin can actually make the shoulders look narrower. The mass climbs inward and upward instead of sitting wide and low. The V taper suffers, the frame looks compressed. Johnny Jackson, one of the strongest bodybuilders to ever compete. His traps were so thick, so dense, from the front, his head looked like it was sitting directly on his shoulders. No neck, just traps then jaw.

[00:02:30]That's not a training outcome. That's where the muscle originates. He didn't build that problem. He was born with it.

[00:02:36]Hamstrings. From the front, you can't even see the hamstrings, but turn around on stage, and they decide everything.

[00:02:43]The biceps femoris runs down the back of the thigh. Where it inserts near the knee determines how the entire leg reads from behind. Low insertion. The muscle runs almost the full length of the thigh, glute to knee, potentially filled, dense, no gaps, depending on how the muscle belly develops. High insertion. The leg tapers early. The lower portion stays thin, no matter how hard the athlete trains. That empty space near the knee just sits there. Kai Greene turned around on stage, and his legs looked like they had no end, full from top to bottom. The separation between heads visible from a distance.

[00:03:20]His legs looked longer than they were, fuller than almost anyone in the sport.

[00:03:24]That wasn't training. Everyone at that level trains. That was just where the muscle stopped. Glutes. The gluteus maximus is one of the largest muscles in the body, and most athletes spend years trying to build what some people are just born with. A higher insertion concentrates the muscle upward. It can create that shelf, rounded, projected, visible from every angle even when relaxed. But how pronounced that projection actually becomes still depends on the muscle belly itself. A lower insertion spreads the muscle further down the femur. The muscle runs longer. In most athletes, that means less shelf, less projection. But in rare cases, it creates something entirely different, not a shelf, a wingspan.

[00:04:07]Ronnie Coleman. His glute insertion sat exceptionally low. The muscle ran the full length of the hip and kept going, spreading outward and downward in a shape the sport had never seen before and hasn't seen since. From behind, his glutes opened like wings, like a butterfly pinned to the widest point of his frame. Eight Olympias. Every rear pose, the same story.

[00:04:29]That shape wasn't built, it was inherited. Now flip it. A high insertion with poor development is the other end of that spectrum. The muscle sits short, compressed near the top of the hip. From behind, flat. No projection, no shape, no separation from the hamstring, just a wall of skin where a glute should be.

[00:04:48]Most men who never train glutes live here, and some who do train and still can't get there live here, too. In wellness, the glute is everything. It's the center of the judging criteria, and the athletes who dominate that category almost always share one thing, a low insertion that lets the muscle belly run long and round, creating that full three-dimensional shape that defines the division. Athletes with a high insertion in wellness fight twice as hard for half the result. You can build a bigger glute, you can't build that silhouette.

[00:05:21]Adductors. The adductors get judged from everywhere, front, side, rear, three-quarter. There's no angle where they disappear. The adductor group runs along the inner thigh from the pelvis toward the knee. Where they insert determines the inner sweep, that curve on the inside of the leg that either completes a physique or exposes it. Low insertion fills the inner thigh further down. The legs can look wider, thicker, but how complete that sweep looks still depends on the muscle belly itself. High insertion leaves a gap near the knee.

[00:05:52]The legs can be enormous and still look incomplete. That thinning on the inside, right above the knee, always there, never filling in. Look at any open lineup. The athletes with the most complete legs almost always have adductors that run the full length of the inner thigh.

[00:06:10]A leg without inner sweep is just a quad, and quads alone don't win shows.

[00:06:15]Serratus. Most bodybuilders never think about the serratus, and it shows. The [snorts] serratus anterior wraps around the side of the rib cage. Those finger-like projections visible between the chest and the lats. It sits right at the junction between the two, filling the space that separates a complete physique from one that just looks flat from the side. A well-developed serratus adds depth and roundness to the V taper that no amount of lat pulldowns creates alone. But here's what nobody talks about. The number of visible fingers and how far down they descend is determined by two things, both genetic. How many ribs the muscle originates from, and how low those origins sit on the rib cage.

[00:06:59]Origins extending down to the ninth or tenth rib, more fingers, more coverage, descending further down the torso. Stop at the seventh or eighth, fewer fingers, higher up. Even at extreme conditioning, the detail simply isn't there. Frank Zane, three Olympia titles.

[00:07:20]The most aesthetic [music] physique the sport has ever seen.

[00:07:28]More fingers than most, lower origin than most. His serratus descended far down the rib cage, visible, detailed, almost architectural. That wasn't conditioning alone, that was genetics.

[00:07:41]You can train it, you can lean out, you can bring it in. What you were born with, that was decided before you ever stepped in a gym. Drop in the comments, which one of these do you actually have?

[00:07:52]Click the subscribe button. Class isn't over.