Leonard's body was being pulled towards the creature as though he were falling out of the sky. The gravity had been manipulated in some way, yet the creature moved as though it hadn't.
'Like it wasn't already strong enough, dealing with shit like this is just annoying!' Leonard thought. 'Complaining isn't going to get me anywhere so I'll just your own attack against you!'
Because Leonard wasn't in the air when the gravity was changed, he was still near the ground, sliding and bouncing along the floor as he 'fell'.
As Leonard neared the creature, it lifted its hand out towards him like it was planning to catch his body.
Instead of allowing the creature to have its way, once he judged the distance was right, Leonard dug his heels into the ground and jumped straight up.
Relative to his current situation it felt the same as it would if you were to jump between two walls.