The knee-chest position, also called genupectoral position, is a spanking position in which the spankee assumes the on-all-fours position and then lowers their chest so that their cheast and head touches the ground/mattress and their bottom sticks up into the air. This position is often assumed when the spankee is on a bed. The spankee can turn their head sideways to breathe easier.
The knee-chest position can be uncomfortable as it places stress on the spankee's stomach. The spankee can spread their knees slightly for better comfort. This position results in the spankee's anus and genitals being exposed (for males, mainly the scrotum). Care must be taken not to accidentally hit the testicles. In erotic spanking, the knee-chest position allows a spanker to play with the spankee's genitals and stimulate them while spanking the spankee's bottom.