Backstroke and freestyle have much in common, and are known as long axis strokes.
The principles of form, balance and shaping apply to all strokes, as explained in previous articles.
Body position in backstroke is a vital factor, a flat position on the back is even more of a drawback than it is in freestyle. The shoulders are much deeper in the water, giving a broad front of resistance, in fact the whole body rides deeper in backstroke.
A help to correct body position where the swimmer drops the hips, is to have the swimmer lying flat on his/her back on the pool deck. By tilting the pelvis upwards, the backbone in the lumbar region is flattened against the deck. Make sure that they've got it right by placing your hand under the small of the back, they should squash your hand against the deck.
Pushing off from the wall, underwater, and holding this position ( head and arms in the proper push-off position) should cause the swimmer to slip through the water remaining horizontal and at the same level, if they are well balanced. This position also minimises drag from the butt, and gets the hips and thighs well up on the water. (This technique is recommended by a backstroke coach, who coached more than one world champion, but is not mentioned by Prof Boomer)
A good way to reinforce the correct position, is to have the swimmer kick along, arms extended, with the pelvis tilted and perfectly streamlined; then break into the full stroke holding this position. You will notice that the kick is at a much better depth.
However, remember that the body is still pushing water up front; in terms of resistance only a small but important form improvement has been made.
To limit the very significant frontal resistance, the body has to be turned on the sides, to have the water flow over two surfaces and so reduce the resistance.
It follows logically, that you should spend as little time on your back as possible.
What we said about hips and using the body to pull the arms for propulsion in freestyle, remains true here as well.
Advice from the top backstrokers is; that you find your stroke from the hips.