Muscles worked
In scissor kicks your hip flexors carry your legs while your abs hold your pelvis and lower back in place. Your inner thighs pull your legs across each other and the outside of your hips moves them apart, so the crossing gives your legs a bit more to do than a kick that only goes up and down. Height sets the difficulty: the closer your legs are to the floor, the longer the lever and the harder your abs work.
Common mistakes
- The crossings get wide and sloppy. Your feet should pass each other by a foot's width or two, not be flung out to the sides.
- Your pelvis rocks with your legs. Your hip bones should stay still and level as you switch the top leg. Brace your abs as if for a light shove and let the movement come from your hip joints.
- Your legs drift up towards the ceiling. Raising them is right when your lower back lets go, but pointing them straight up lets your abs almost rest. Work at the lowest height at which your back stays down.
Variations and alternatives
- Flutter kicks use the same start position, but your legs kick up and down instead of crossing.
- The lying leg raise trains the same muscles with slow, large movements counted in reps.
- The dead bug is easier and suits you if your lower back lifts even with your legs held high.
Sets and reps
Scissor kicks are usually done for time: 20 to 40 seconds per set, two or three sets, with roughly equal rest. Your lower back decides when you stop, and once it lifts off the floor and will not go back down, you are done. The guide to sets and reps covers how to choose between time and reps.
Add time first, then lower your legs closer to the floor, and finally lift your head and shoulders slightly for the whole set. As long as one of those goes up over the weeks, you have progressive overload in an exercise with no weights. If your lower back feels painful rather than your abs feeling tired, stop and have a doctor or physiotherapist look at it.