take, for example, changing crib sheets. seriously. this is not an easy task. do you take the mattress completely out of the crib (which involves removing bumper pads)? do you leave the mattress in? i've attempted both ways. many times. and, really, any way you cut it, the work is simply back-breaking.
especially if you are attempting to stretch a "cheaper" sheet over the mattress. you know those 2/$5.00 sheets you buy as "back ups" for times when the good sheets are dirty. here's a thought: the 2/$5.00 packages should come with an ice pack and instructions "for use on aching body after applying sheet to mattress". because, really, without the ice pack...you're just getting a bargain of a backache.