Abs: what the muscles of the abdominal wall do, and what trains each part
The front and sides of your midsection. They bend the trunk and twist it, and by raising the pressure inside the abdomen they can help steady it under a heavy load.
By Kiptly ·
On this page
- Where they are, and what they move
- At a glance
- What that first number is not
- The abs as a whole
- Exercises for the abs as a whole
- The upper abs
- Exercises for the upper abs
- The lower abs
- Exercises for the lower abs
- The obliques
- Exercises for the obliques
- Training them with no equipment
- Trained alongside
- What this page does not tell you
Where they are, and what they move
The front and sides of your midsection are a wall of five paired muscles. Down the middle runs the rectus abdominis, long and narrow, from the pubic bone up to the cartilages of the fifth to seventh ribs. Three bands of tendon cross each side of it and divide it into four segments — in an athlete they can show as a six-pack. A small triangular muscle, the pyramidalis, lies over its lowest part.
At the sides lie three flat layers. The external oblique is the outermost, its fibres running from the lower ribs downward and inward; the internal oblique lies just beneath it, its fibres at right angles to them, running upward and inward; and the transversus abdominis is the deepest, its fibres running straight across. All three turn into sheets of tendon that wrap around the rectus abdominis and meet in the midline.
The reference calls the rectus abdominis a powerful flexor of the spine: it bends the trunk forward. The two obliques, working together, turn the spine and bend it to the side, and the transversus abdominis squeezes what lies inside the abdomen. Contracting at once, the muscles raise the pressure inside it — the pressure behind a cough or a sneeze — which may also help steady the trunk when you lift something heavy.
Kiptly’s catalogue divides the abs into three parts — the upper abs, the lower abs and the obliques — and, unlike the back, the shoulders or the chest, it also files a group of movements under the abs as a whole. Its upper and lower abs are not two muscles: the reference describes one rectus abdominis on each side, from the pubic bone to the ribs. They are where the catalogue files a movement — most of the crunches under the upper abs, the leg and knee raises under the lower.
At a glance
What Kiptly’s own exercise catalogue says about these muscles. These numbers are generated from the same data the app uses to fill your workout — nothing here is a marketing figure, and nothing is typed by hand.
- name it as the main muscle
- 66
- name it as a secondary muscle
- 47
- kinds of equipment
- 10
- of those are compound
- 17
Of the exercises that name it — strength 41 · static hold 17 · stretching 4 · plyometric 3 · cardio 1
The abs as a whole
Under the abs as a whole the catalogue files the ab wheel rollout, from the knees and standing, the dragon flags — from the tucked flag to the full one — the dead bug, the Swiss-ball pike, the cable crunch and the machine crunch, and two movements that name a second muscle as primary: the Pallof press, which names the obliques, and the Turkish get-up, which names the front part of the shoulder.
Exercises for the abs as a whole
Every strength exercise in the app that names the abs as a whole as a primary muscle — not one of their parts — with the equipment it needs and how the catalogue grades it. Grouped by equipment, largest group first — the app does not rank movements and neither does this table.
| Exercise | Equipment | Level | Type |
|---|---|---|---|
| Dead Bug | Bodyweight | Beginner | Compound |
| Kneeling Ab Wheel Rollout | Bodyweight | Intermediate | Compound |
| Single-Leg Dragon Flag | Bodyweight | Intermediate | Compound |
| Tuck Dragon Flag | Bodyweight | Intermediate | Compound |
| Dragon Flag | Bodyweight | Advanced | Compound |
| Standing Ab Wheel Rollout | Bodyweight | Advanced | Compound |
| Straddle Dragon Flag | Bodyweight | Advanced | Compound |
| Cable Crunch | Cable Machine | Intermediate | Isolation |
| Pallof Press | Cable Machine | Intermediate | Compound |
| Turkish Get-Up | Kettlebell | Advanced | Compound |
| Machine Crunch | Machine | Beginner | Isolation |
| Swiss Ball Pike | Swiss Ball | Advanced | Compound |
How each exercise is done
The same descriptions the app shows on each exercise’s screen.
Dead Bug
Lying on your back and lowering the opposite arm and leg while your lower back stays on the floor. Lie with your arms pointing at the ceiling and your hips and knees bent at right angles. Slowly lower one arm behind your head and the opposite leg towards the floor, keeping your back flat, then return and switch sides.
Kneeling Ab Wheel Rollout
Rolling an ab wheel out and back from your knees, with your trunk held straight. Kneel on a mat with the wheel on the floor under your shoulders and your arms straight. Roll it forward slowly, letting your hips follow your shoulders and keeping your back from sagging, as far as you can control, then pull it back under you with your stomach rather than by sitting your hips back.
Single-Leg Dragon Flag
A dragon flag with one leg straight and the other knee bent towards your chest. Lie on a bench gripping it behind your head and lift your body onto your upper back. Lower slowly as one line from your shoulders to your straight leg, without bending at the hips, then raise yourself back up. Switch legs between sets.
Tuck Dragon Flag
A dragon flag with both knees tucked in towards your chest. Lie on a bench gripping it behind your head and lift your hips onto your upper back with your knees bent tightly. Lower your hips slowly towards the bench while holding the tuck, then raise them back up without swinging your legs.
Dragon Flag
Lowering your whole body as one straight line from the shoulders while holding a bench behind your head. Lie on a bench and grip it behind your head, then lift your hips and legs until your body is straight and nearly vertical, resting on your upper back. Lower slowly, keeping a straight line from shoulders to feet without bending at the hips, then raise yourself back up.
Standing Ab Wheel Rollout
An ab wheel rollout from your feet rather than your knees. Stand with your feet about hip-width apart, hinge forward and set the wheel on the floor in front of your feet. With your arms straight, roll it forward slowly until your body is nearly level with the floor, your back flat and your hips following your shoulders, then pull it back towards your feet with your stomach. Done from the knees it is easier.
Straddle Dragon Flag
A dragon flag with your straight legs spread wide apart. Lie on a bench gripping it behind your head, lift your hips and legs onto your upper back and open your legs as wide as you comfortably can. Lower slowly as one straight line from your shoulders to your hips, then raise yourself back up without bending at the hips.
Cable Crunch
A crunch kneeling under a high cable, curling your trunk down against the weight. Attach a rope to a high pulley, kneel facing the machine and hold the rope beside your head. Keeping your hips still, curl your ribs down towards your pelvis until your elbows near your thighs, then uncurl slowly back to upright.
Pallof Press
Pressing a cable handle straight out from your chest while the cable tries to turn you towards the machine. Set the pulley at chest height, stand side-on to the machine with your feet apart and hold the handle with both hands against your chest. Press it straight out in front of you, hold briefly without letting your trunk turn, then bring it back. Finish one side, then switch.
Turkish Get-Up
Getting up from lying on the floor to standing, and back down, with a kettlebell held overhead the whole time. Lie on your back with the bell pressed above your shoulder and the knee on that side bent. Roll onto your free elbow, then your hand, lift your hips, sweep the straight leg back under you into a half kneel and stand up, eyes on the bell. Reverse each step to lie back down. Finish one side, then switch.
Machine Crunch
A crunch against the weight stack of an ab crunch machine. Sit with your back against the pad, hook your feet under the rollers and take the handles or the pads at your chest. Curl your chest down towards your hips by rounding your upper back, pause briefly, then let the weight bring you back up slowly without losing the tension.
Swiss Ball Pike
Lifting your hips into a pike from a push-up position with your feet on a Swiss ball. Start with your hands under your shoulders and your shins on the ball, your body straight. Keeping your legs straight, raise your hips towards the ceiling so the ball rolls in towards your hands, then lower your hips slowly back into a straight line.
The upper abs
The upper abs’ list is mostly crunches: on the floor, reaching for the toes, holding a weight, on a decline bench and on a Swiss ball. Four more name a second part as primary: the bicycle crunch names the obliques, and the V-up and the two sit-ups, on the floor and on a decline bench, the lower abs.
Exercises for the upper abs
Every strength exercise in the app that names the upper abs as a primary muscle. A movement that names two parts appears in both of their tables.
| Exercise | Equipment | Level | Type |
|---|---|---|---|
| Bicycle Crunch | Bodyweight | Beginner | Isolation |
| Crunch | Bodyweight | Beginner | Isolation |
| Sit-Up | Bodyweight | Beginner | Isolation |
| Toe Touch Crunch | Bodyweight | Beginner | Isolation |
| V-Up | Bodyweight | Intermediate | Compound |
| Decline Crunch | Bench | Intermediate | Isolation |
| Decline Sit-Up | Bench | Intermediate | Isolation |
| Weighted Crunch | Dumbbell | Intermediate | Isolation |
| Swiss Ball Crunch | Swiss Ball | Beginner | Isolation |
How each exercise is done
The same descriptions the app shows on each exercise’s screen.
Bicycle Crunch
A crunch that brings each elbow towards the opposite knee in turn while your legs pedal. Lie on your back with your hands lightly behind your head and your feet off the floor. Lift your shoulders and turn your trunk to bring one elbow towards the opposite knee as that leg bends and the other straightens, then switch sides in a steady rhythm.
Crunch
Curling your shoulders up off the floor while your lower back stays down. Lie on your back with your knees bent and your feet flat, hands lightly behind your head or across your chest. Curl your head and shoulders up by bringing your ribs towards your pelvis, pause briefly, then lower slowly without pulling on your neck.
Sit-Up
Sitting all the way up from lying on your back with your knees bent — a longer range than a crunch. Lie with your knees bent and your feet flat on the floor, hooked under a pad if you like, and your arms crossed on your chest or your hands lightly behind your head. Curl your upper back off the floor and keep rising until your chest is near your thighs, then lower yourself back down slowly, one vertebra at a time.
Toe Touch Crunch
A crunch reaching your hands up towards your toes with your legs raised. Lie on your back with your legs straight up towards the ceiling and your arms reaching towards your feet. Curl your shoulders off the floor and reach your fingers towards your toes, then lower slowly, keeping your legs still.
V-Up
Lifting your straight legs and your trunk at the same time so your body folds into a V. Lie on your back with your arms stretched overhead and your legs straight. Raise your legs and your upper body together, reaching your hands towards your feet, balance briefly on your seat, then lower both slowly back to the floor.
Decline Crunch
A crunch on a bench set at a decline, with your feet hooked higher than your head. Hook your feet under the pads and lie back with your hands lightly behind your head or across your chest. Curl your shoulders and upper back up towards your knees, then lower slowly until your shoulders nearly touch the bench.
Decline Sit-Up
A sit-up on a bench set at a decline, with your feet hooked higher than your head, which makes the whole range harder. Hook your feet under the pads and lie back with your arms crossed on your chest. Sit up until your chest is close to your thighs, then lower yourself slowly until your back nearly touches the bench.
Weighted Crunch
A crunch holding a dumbbell against your chest. Lie on your back with your knees bent and your feet flat, the dumbbell held in both hands on your chest. Curl your head and shoulders up by bringing your ribs towards your pelvis, then lower slowly. A heavier dumbbell makes it harder.
Swiss Ball Crunch
A crunch lying back over a Swiss ball. Sit on the ball, walk your feet forward and lie back until the ball supports your lower and middle back, feet flat and apart for balance. Curl your shoulders up by bringing your ribs towards your pelvis, then lower slowly back over the ball.
The lower abs
The lower abs have the longest list: the knee and leg raises, lying on the floor and hanging from a bar, from bent knees to straight legs; the knee raise in a captain’s chair; the knee tucks, lying and seated; the reverse crunch, the flutter kick, the two sit-ups, the V-up and the mountain climber. The V-up and the mountain climber are the only compound movements on it.
Exercises for the lower abs
Every strength exercise in the app that names the lower abs as a primary muscle, grouped by equipment like the tables above.
| Exercise | Equipment | Level | Type |
|---|---|---|---|
| Flutter Kick | Bodyweight | Beginner | Isolation |
| Knee Raise (Captain's Chair) | Bodyweight | Beginner | Isolation |
| Lying Bent Leg Raise | Bodyweight | Beginner | Isolation |
| Lying Knee Raise | Bodyweight | Beginner | Isolation |
| Lying Knee Tuck | Bodyweight | Beginner | Isolation |
| Lying Leg Raise | Bodyweight | Beginner | Isolation |
| Mountain Climber | Bodyweight | Beginner | Compound |
| Reverse Crunch | Bodyweight | Beginner | Isolation |
| Sit-Up | Bodyweight | Beginner | Isolation |
| Lying Straight Leg Raise | Bodyweight | Intermediate | Isolation |
| V-Up | Bodyweight | Intermediate | Compound |
| Hanging Knee Raise | Pull-up Bar | Beginner | Isolation |
| Hanging Bent Leg Raise | Pull-up Bar | Intermediate | Isolation |
| Hanging Leg Raise | Pull-up Bar | Intermediate | Isolation |
| Hanging Straight Leg Raise | Pull-up Bar | Advanced | Isolation |
| Seated Knee Tuck | Bench | Beginner | Isolation |
| Decline Sit-Up | Bench | Intermediate | Isolation |
How each exercise is done
The same descriptions the app shows on each exercise’s screen.
Exercises already described under a table above are not repeated here.
Flutter Kick
Kicking your straight legs up and down in small, quick movements while lying on your back. Lie with your arms by your sides or your hands under your hips and lift both legs a little off the floor. Kick one leg up as the other goes down, alternating in a steady rhythm with your lower back pressed into the floor.
Knee Raise (Captain's Chair)
Raising your knees while you hold yourself up on your forearms in a captain's chair. Step up, rest your back against the pad and your forearms on the arm pads, grip the handles and let your legs hang. Bring your knees up towards your chest, then lower them slowly without swinging.
Lying Bent Leg Raise
A lying leg raise with your knees bent at a right angle. Lie on your back with your arms by your sides and your lower back pressed into the floor. Lift your thighs until they point straight up, keeping the bend in your knees, then lower them slowly, stopping before your lower back lifts. Straightening your legs makes it harder.
Lying Knee Raise
Bringing your knees in towards your chest while lying on your back. Lie with your arms by your sides, legs straight and your heels just off the floor. Bend your hips and knees to draw your knees towards your chest, then straighten your legs back out slowly without letting your heels touch the floor.
Lying Knee Tuck
Tucking your knees in to your chest while lying on your back, your shoulders lifting to meet them. Lie with your hands beside your hips and your legs straight just off the floor. Draw your knees in to your chest and lift your shoulders a little, then push your legs back out slowly.
Lying Leg Raise
Raising your legs while lying on your back, with your knees bent or straight. Lie with your arms by your sides and your lower back pressed into the floor. Lift your legs until they point at the ceiling, then lower them slowly, stopping before your lower back lifts off the floor. The bent-knee and straight-leg versions are listed on their own.
Mountain Climber
Driving your knees towards your chest in turn from a push-up position, as if running. Start with your hands under your shoulders and your body straight from head to heels. Bring one knee towards your chest, then switch legs, returning one foot as the other comes forward, with your hips level and your shoulders over your hands. Keep a steady pace you can hold.
Reverse Crunch
Curling your hips up off the floor towards your chest, the crunch turned the other way round. Lie on your back with your knees bent, thighs pointing up and arms by your sides. Roll your pelvis up so your hips lift off the floor and your knees come towards your chest, then lower your hips slowly back down.
Lying Straight Leg Raise
Raising straight legs while lying on your back. Lie with your arms by your sides and your lower back pressed into the floor. With your knees straight, lift your legs until they point at the ceiling, then lower them slowly, stopping before your lower back lifts off the floor.
Hanging Knee Raise
Raising the knees while hanging from a bar. Hang with your arms straight and your body still, then bend your hips and knees to bring your knees up towards your chest, tilting your pelvis up at the top. Lower your legs slowly without swinging, and start each rep from a still hang.
Hanging Bent Leg Raise
Raising bent legs while hanging from a bar, higher than a knee raise. Hang with straight arms and your body still, knees bent at about a right angle. Raise your thighs until they are level with the floor or higher, tilting your pelvis up at the top, then lower slowly without swinging.
Hanging Leg Raise
Raising your legs while hanging from a bar, with your knees bent or straight. Hang with your arms straight and your body still, then lift your legs in front of you until your thighs are at least level with your hips, tilting your pelvis up at the top. Lower them slowly without swinging. The bent-knee and straight-leg versions are listed on their own.
Hanging Straight Leg Raise
Raising straight legs while hanging from a bar. Hang with your arms straight and your body still, then lift your legs in front of you, knees straight, until they reach at least hip height, tilting your pelvis up at the top. Lower them slowly without swinging, and start each rep from a still hang.
Seated Knee Tuck
Drawing your knees in to your chest while sitting on the edge of a bench. Sit near the edge, hold it behind your hips, lean back slightly and stretch your legs out in front of you with your feet off the floor. Pull your knees in towards your chest as your trunk leans in to meet them, then stretch your legs out again without letting your feet touch the floor.
The obliques
The obliques’ strength list is the Russian twists — on the floor, with a medicine ball and on a decline bench — the cable woodchop, the Pallof press, the kettlebell windmill, the dumbbell side bend and the bicycle crunch. Most of the rest that names them is holds: the side plank, the vertical flag, the human flags and a Pallof hold on a cable. Two stretches that twist the spine and a rotational medicine-ball throw complete it.
Exercises for the obliques
Every strength exercise in the app that names the obliques as a primary muscle, grouped by equipment like the tables above.
| Exercise | Equipment | Level | Type |
|---|---|---|---|
| Bicycle Crunch | Bodyweight | Beginner | Isolation |
| Russian Twist | Bodyweight | Beginner | Isolation |
| Cable Woodchop | Cable Machine | Intermediate | Compound |
| Pallof Press | Cable Machine | Intermediate | Compound |
| Decline Russian Twist | Bench | Intermediate | Isolation |
| Dumbbell Side Bend | Dumbbell | Beginner | Isolation |
| Kettlebell Windmill | Kettlebell | Intermediate | Compound |
| Medicine Ball Russian Twist | Medicine Ball | Beginner | Isolation |
How each exercise is done
The same descriptions the app shows on each exercise’s screen.
Exercises already described under a table above are not repeated here.
Russian Twist
Turning your trunk from side to side while sitting and leaning back. Sit with your knees bent and your heels on the floor or just above it, and lean back a little with your back straight. Clasp your hands in front of your chest and turn your shoulders to one side, then to the other, keeping your hips still.
Cable Woodchop
A diagonal pull across the body on a cable, turning through the trunk. Set the pulley high, stand side-on with your feet apart and hold the handle with both hands above the shoulder nearer the machine. Pull it down and across to the outside of the opposite knee, turning your trunk and pivoting on the back foot, then let it return under control. Finish one side, then switch.
Decline Russian Twist
A Russian twist sitting back on a bench set at a decline. Hook your feet under the pads and lean back with your trunk at an angle, hands together in front of your chest. Turn your shoulders to one side, then the other, moving your hands with them while your hips stay still.
Dumbbell Side Bend
Bending sideways at the waist with a dumbbell in one hand, for the obliques. Stand tall with your feet hip-width apart, the dumbbell hanging at your side and your other hand on your hip. Lower the dumbbell down your leg by bending to that side without leaning forward or back, then use the opposite side of your waist to pull yourself upright; finish the set before switching hands.
Kettlebell Windmill
Folding sideways at the hips while holding a kettlebell overhead. Press the bell overhead with one arm and turn both feet away from that side. Watching the bell, push your hips towards the loaded side and fold your torso down towards the other leg, sliding your free hand down it towards the floor while the arm overhead stays straight. Return to standing the same way. Finish one side, then switch.
Medicine Ball Russian Twist
A Russian twist holding a medicine ball. Sit with your knees bent, lean back with a straight back and hold the ball in front of your chest. Turn your trunk to bring the ball beside one hip, then the other, keeping your hips still and your feet on the floor or just above it.
Training them with no equipment
More than half of the four tables is filed as bodyweight work, and a bar to hang from adds the hanging raises. The catalogue grades the ladders it holds: the ab wheel goes from the rollout on the knees, graded intermediate, to the standing one, graded advanced; the dragon flag from the tucked and the single-leg flag, graded intermediate, to the straddle and the full flag, graded advanced; the hanging raises go from the knee raise, graded beginner, through the bent-leg raise and the leg raise, graded intermediate, to the straight-leg raise, graded advanced.
None of the movements on this page carries a share of your body mass. The catalogue gives a share only where the mass a movement raises has been measured or can be worked out from the body’s segments, and for none of these has it been — a crunch, its own notes say, is a lever rather than a lift. So a set counts only the weight you type, unless you give the exercise a share of your own.
How the shares are worked out, and which exercises have one, is a question for the How it works section of this site — its page on volume and the muscle map — rather than for this one.
Trained alongside
Which other muscles the same exercises name, primary or secondary. This is a map of what you cannot help training when you train these — read it as overlap, not as a plan.
| Muscle group | Exercises |
|---|---|
| Back | 20 |
| Shoulders | 20 |
| Quadriceps | 9 |
| Triceps | 4 |
| Forearms | 3 |
| Glutes | 3 |
| Biceps | 1 |
| Chest | 1 |
| Hamstrings | 1 |
Sources
Each source says how far we actually got into it. A citation list shows that a paper exists, not that anybody opened it — so this one is labelled.
Anatomy, Abdomen and Pelvis: Abdominal Wall
Flynn W, Vickerton P. StatPearls, last updated 24 July 2023. Open-access reference article. The five paired muscles of the wall, where the rectus abdominis starts and attaches and how it is divided, the three flat layers and the run of their fibres, what each does to the spine, and the pressure they raise together all come from here.
Read in full
Kiptly exercise catalogue
The same data the app ships. Every count and every table on this page is generated from it and checked against it on every build.
Read in full
General fitness information, not medical advice.