Then you are getting about half the height you could if you used your arms.
So not something a top class athlete can get away with.
Your arms go up, down, then up again when you jump up to increase leap height and aid in balance and movement in the air.
In fact, literally the only way to move once you are off the ground is by moving your limbs, especially your arms.
That is quite literally elementary physics.
Anyone claiming you can move in the air, in a way needed as a professional athlete, without moving your arms, is a liar or a moron or both.