Obliques

core2 muscles

The obliques are the two layers of muscle on the sides of your abdomen that twist your torso and bend it sideways. They are what a Russian twist, a woodchop and a side bend all train.

Obliques: its 2 muscles highlighted on an anatomical figure, from the front — External Oblique and Internal Oblique.
Where the obliques sit, from the front.

There are two of them on each side, and they cross. The external oblique is the outer layer, its fibres running downward and forward — the direction your fingers point when you slide your hands into your front pockets. The internal oblique lies underneath with its fibres running the other way, upward and forward. Between them they form a criss-cross around the waist.

That crossing arrangement is what makes rotation work. To turn your torso to the left, the external oblique on your right side works with the internal oblique on your left, because their fibres line up across the body. Every rotation is a partnership between the outer layer on one side and the inner layer on the other, which is why nothing can train one without the other.

They also bend the trunk sideways, and both layers on the same side do that together. And along with the transversus abdominis underneath, they compress the abdomen — which is what makes the whole midsection rigid when you brace against a heavy weight.

Grouping them under one name is gym vocabulary rather than anatomy: they are two distinct muscles with different fibre directions and different jobs in rotation. But since no movement separates them, one name is the honest simplification.

The obliques are not a way to change the shape of the waist. Training them makes them thicker, and a thicker muscle at the side of the abdomen is not a narrower waist — the myth runs in exactly the wrong direction.

Training notes

Rotation and side bending are what train them, and neither is part of most programs. Woodchops, cable rotations, Russian twists, side bends and windmills all qualify; crunches and leg raises do not, however much the obliques stabilise during them.

Anti-rotation is the third category and the most useful one for lifting. A Pallof press — holding a cable out in front of you while it tries to twist you — trains the obliques to refuse to rotate, which is what they do while you carry something heavy on one side or press overhead with one arm.

Weighted side bends have a long-standing reputation for widening the waist. The mechanism is real in the sense that any muscle grows when trained, but the effect is small and slow, and it is a poor reason to skip training a muscle that rotates the trunk. If waist appearance is the goal, body fat is the variable that matters.

Because rotation is one-sided by nature, oblique work needs both directions and roughly equal volume. It is easy to do more repetitions to a dominant side without noticing.

One or two rotational movements a week covers them. They are already working hard during squats, deadlifts, carries and any single-arm work, so what they lack is not volume but the rotation itself.

Muscles in this group

Exercises

Antagonists

Synergists