Russian twist
- Muscle:
- obliques
- Equipment:
- bodyweight or plate
Why it's worth doing
The russian twist trains real loaded trunk rotation, something a crunch, a leg raise, or a side plank don't do: those exercises move in the sagittal plane or resist sideways bending, but none of them turn the torso from side to side under load.
That loaded rotation works differently from rotating the thoracic spine: the lumbar facet joints are oriented to allow flexion and extension, not rotation, so the lumbar vertebrae have far less rotational travel available before the load lands on the disc instead of the bone. That's the concrete anatomical reason behind the debate around this exercise, not just a trainer's opinion repeated without grounding.
What does seem to lower the risk, and most of that same debate agrees on this much, is where the turn comes from: if the rotation comes from the torso, ribs turning over a pelvis that stays put, instead of forcing the lower back past its comfortable range, and if the feet aren't used as an anchor to generate momentum, the exercise looks a lot less like the pattern that worries people. With that technique, and without chasing maximum loads, the russian twist can add a rotational stimulus other ab exercises don't offer.
How to do it
- Sit on the floor with your knees bent and heels down, leaning your torso back about 45 degrees without rounding your lower back.
- Lift your feet off the floor if your level allows it, balancing with your abs, not your arms.
- Hold your hands together in front of your chest, or a plate with both hands, without pressing it against your body.
- Rotate your torso to one side, bringing your hands near your hip, starting the turn from your ribs, not your lower back.
- Barely tap the floor beside your hip without letting your hips rotate along with your torso or your feet drop suddenly.
- Return to center under control and rotate to the other side, keeping the same torso angle for the whole set.
- Repeat at a steady pace, stopping the set before fatigue forces you to compensate with your lower back.
Muscles worked
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. It's one of the few core exercises where the obliques actively rotate the trunk instead of just resisting it bending to one side, the way they do in the side plank.
The rectus abdominis comes in as a synergist, mostly holding the backward lean the starting position already puts on the torso, but it isn't the star of the turn itself. The hip flexors, psoas and rectus femoris, act as stabilizers holding the legs up in the harder, feet-up version; with the feet planted, they contribute a lot less.
The lower back shouldn't be acting as a mover here at all: its job is to stay relatively still while the turning happens above it, in the torso. When the lower back does move actively to complete the range of the turn, that's the clearest technical sign the movement is being compensated for from there instead of from the obliques, and it's exactly the pattern the debate around this exercise points to as the riskiest one.
Common mistakes
- Rotating the hips along with the torso: turns the movement into a whole-body swing and takes the rotational work away from the obliques.
- Using momentum from the plate or the arms to finish the turn instead of starting it from the torso: cuts the abs' real workload down to almost nothing.
- Forcing the range of rotation past what's comfortable just to tap the floor with the plate: it's the exact combination, forced, loaded, repeated lumbar rotation, that coaches question most.
- Letting the feet drop suddenly between reps in the feet-up version: loses the ab tension that holds that position up.
Russian twist or side plank
Russian twist or side plank compares two opposite ways of training the same plane of movement: one rotates the trunk against resistance, the other resists the trunk bending to one side under a static load.
The side plank is isometric and involves no actual rotation: the obliques contract to keep the torso from moving while gravity pulls the hips toward the floor. None of the loaded-lumbar-rotation debate that surrounds the russian twist applies here, because the spine never turns at any point.
The russian twist, by contrast, moves the torso from side to side against resistance, and that's exactly the function the side plank doesn't train: the ability to generate rotational force, not just resist it. It's the same split that separates an anti-movement exercise from an active-movement one, and neither replaces the other.
The real question isn't which one to pick instead of the other; it's what technique each one demands. The side plank has almost no way to go wrong when done well, while the russian twist asks for more attention, the turn has to come from the torso, not the lower back, so the risk several coaches point to doesn't show up. Someone just starting with rotational core work usually benefits from mastering the side plank first, learning to control the trunk under a sideways force, before adding the active rotation the russian twist asks for.
Frequently asked questions
Is the russian twist bad for your back?
It's an exercise plenty of coaches question, and for a real reason: adding loaded, repeated lumbar rotation is linked to a higher risk of disc irritation than other core patterns carry. That doesn't make it off-limits, but it does change how it needs to be done: the turn has to come from the torso, not from forcing the lower back past its comfortable range, and the feet aren't the anchor holding the movement together. With that technique and a reasonable load, the risk drops quite a bit; without it, this is one of the ab exercises with the most room to cause harm.
Should my feet stay on the floor or come up?
Both are valid: feet down is the entry version, and feet up adds hip-flexor work to hold the legs in the air along with a bigger balance demand. Either way, the feet never act as the anchor holding the turn together; that job belongs to the abs contracting, not to the heels pressing into the floor. If you feel like you need to dig your heels in to keep from falling, that's a sign your abs aren't holding the position on their own yet.
When does it make sense to add a plate?
Only once the unweighted version holds a constant torso angle without the hips joining the turn. Adding load before that just magnifies the technical error: more weight rotating over a lower back that was already compensating for the abs is exactly the combination that worries people who question this exercise.
Does the russian twist give you a defined waist or shrink it?
No. It strengthens the obliques, but that doesn't decide whether they show or shrink fat in that specific area; that comes down to overall body fat percentage, set by diet and calorie balance, not by picking which muscle to train. Spot-reducing fat by training one muscle isn't something that happens.
Similar exercises
The cable crunch trains spinal flexion with progressive load, a plane the russian twist never touches: together they cover rotation and flexion, two of the basic movements the abs need to handle. To cover the third, resisting movement instead of producing it, the dead bug trains the lumbopelvic control that makes russian twist technique safer: someone who can't keep their lower back still during the dead bug probably won't keep it still while rotating under load either.