Core exercises
The crunch and the plank train the core in almost opposite ways, and knowing that difference is what lets you choose between ab exercises on purpose instead of by habit. The crunch, along with the leg raise, actively flexes the spine or the hip against gravity; the dead bug and the side plank do the reverse — they resist the spine moving while some other part of the body does. A program built only around crunches gets half of that job done and leaves the other half, the one that holds the lower back steady under load, completely untouched, even when the rep count looks like plenty. There's a third piece layered on top of that second half: mountain climbers pair that same resistance to spinal movement with a sustained pace that also demands conditioning. What an incomplete program leaves untrained never shows up in the mirror — load-bearing endurance and cardiovascular capacity don't leave a visible mark the way muscle growth does, but they're half of what a well-trained core actually is. Abs are also the muscle the internet lies about most: training it and seeing it are different problems. Solid ab work strengthens the muscle itself — the exercise, the technique and the load progression decide that — but whether it shows up defined comes down to something else entirely, the layer of body fat sitting over it, and no rep count changes that.
Exercises
1. Dead bug
core · bodyweight
The main players are the rectus abdominis together with the transverse abdominis, the deepest layer of the core, which contract isometrically to fix the pelvis and lower back while the arm and leg move.
2. Leg raises
abs · bodyweight
The prime mover is the rectus abdominis, especially its lower portion, which activates harder here than in exercises that flex the torso toward the legs, like the crunch.
3. Crunch
abs · bodyweight
The prime mover is the rectus abdominis, mostly its upper portion: the crunch flexes the upper spine toward the pelvis through a short range, and that's the part of the muscle that shortens the most over that specific stretch.
4. Mountain climbers
core and conditioning · bodyweight
The main movers of the leg action are the hip flexors, psoas and rectus femoris, driving the knee toward the chest over and over.
5. Side plank
obliques · bodyweight
The prime mover is the oblique on the supporting side, both external and internal, which contract isometrically to hold the weight of the trunk against gravity and keep the hips from sagging toward the floor.
6. Russian twist
obliques · bodyweight or plate
The prime movers are the external and internal obliques, working in crossed pairs: the external oblique on one side and the internal oblique on the other contract together to produce each turn, then swap roles when the direction changes.
7. Cable crunch
abs · cable machine
The prime mover is the rectus abdominis, through its whole length: unlike the floor crunch, which mostly works the upper portion, here the range of spinal flexion tends to run a bit longer, so the lower portion picks up a real share of the work too.
Workouts with these exercises
Frequently asked questions
Crunch or plank?
Both, because they train opposite things: the crunch flexes the spine and the plank resists it moving. A program with only crunches leaves out the work of holding the lower back steady under load.
What's the best exercise for the lower abs?
The rectus abdominis is a single muscle from top to bottom, so it isn't trained in separate parts. The leg raise tends to be felt more in the lower part and the crunch in the upper, but the whole muscle works in both.
Are Russian twists worth doing?
They train trunk rotation, which crunches and planks don't cover. Do them slowly with a short twist; if your lower back bothers you, do them without weight, or drop them.
Is the dead bug worth doing?
Yes: it trains your abs to keep your lower back still while your arms and legs move, similar to the work of holding your spine steady in a squat. It's one of the easiest to do well when you start, which is why the beginner routine uses it.
Other muscles
Gojan builds the routine and changes it when you tell it your week falls apart. Download Gojan