The floor wiper is an easier variation of the windshield wiper that can be used as an initial step in a progression, or a substitute.  
 
 
Execution
 
Lie on your back, spread your arms to your sides for a wide base, and bring your straight legs vertically. Slowly rotate to bring your feet to the floor on one side, keeping your legs straight, then back to the other side.
 
 
Purpose
 
The floor wiper is a more accessible variation of the windshield wiper for training trunk rotation without the added demand of the isometric trunk support in a hanging position.
 
 
Programming
 
Sets to maximal reps (not to actual failure) or of 10-20 each direction are typical.
 
 
Variations
 
The motion can be slowed down or the feet not allowed to touch the floor to increase difficulty.