Muscle guide · Core and trunk
Also called side abs, external and internal obliques, waist muscles
The obliques are two flat layers of muscle wrapping the sides of the waist. The external oblique is the outer and larger, with fibres angled down and in like hands sliding into front pockets; the internal oblique lies under it, its fibres crossing at roughly right angles.
Working together they turn and side-bend the trunk, and they help the rest of the abdominal wall brace and squeeze.
| Part | Starts at | Attaches to | What it does |
|---|---|---|---|
| External oblique | Outer surfaces of the lower ribs (sources say the lower seven or ribs 5 to 12) | Top front of the hip bone, the midline seam of the belly, and the groin ligament it forms | Turns the trunk to the opposite side; side-bends and curls it |
| Internal oblique | Top of the hip bone, the deep fascia of the low back and the outer groin ligament | Cartilage of the lower ribs, the midline seam, and the pubic bone | Turns the trunk to the same side; side-bends and curls it |
The side bridge was the best abdominal-wall exercise with little psoas load in a fine-wire EMG study; bird dogs raise internal-oblique activity on the side of the lifted arm, and a single-leg bridge loads the obliques more than a two-leg one.
Twists and side bends reverse their actions; NHS low-back leaflets use them, though none names the obliques.
In fast bowlers, MRI showed tears of the obliques or transversus near their attachments on the lowest ribs, usually on the side opposite the bowling arm, and six of ten were recurrences. In professional baseball, oblique injuries cost about 22 days each, mostly while batting or pitching.
Each grade rates the evidence for the correction.
Six weeks of ab exercise did not change the skinfold over the hips in a randomised trial. Small trials combining ab work with aerobic training disagree, so the most you can say is that oblique work alone is not a reliable way to lose fat there.
The EMG study of loaded trunk rotation concluded that, for safety, load and speed of rotation should be kept low.
Source 5
A 15-minute beginner core workout on the floor: dead bugs, bird dogs, knee planks, side planks and curl-ups.
15 minBeginner6 movesNo equipmentHard core training: ab wheel rollouts, hanging leg raises, L-sits, Copenhagen planks, plank walk-ups and dragon flags.
30 minAdvanced6 movesAn ab wheel, Pull-up barThey twist and side-bend the trunk and help the abdominal wall curl and brace. To turn right, your left external and right internal obliques work together.
The side plank: in a fine-wire EMG study it was the best abdominal-wall exercise while keeping psoas load low.
Not reliably. Six weeks of ab training did not change fat over the hips in a randomised trial.
Anatomy and movement education, not a diagnosis or treatment plan. If you have pain that follows an injury, is severe or getting worse, or comes with numbness, weakness or swelling, get it assessed. Health disclaimer.
