I don't know, but I found this online. Hope it helps: "In a static horizontal float position on your tum (you can flutter kick to keep your legs up while doing this!) have your "lead" arm stretched out in line with your body and your "stroking arm" pointing to the bottom of the pool (while actually swimming that "lead arm " will be just about to enter the water after its recovery!). Now roll away from the arm pointing to the bottom (this means that you will have rolled towards the "lead"arm - Good!), and start "pushing" your "stroking arm" up to the surface, while you simultaneosly turn your neck slightly to inhale (if actually swimming, your mouth will clear the water). Note that while that "stroking arm" is doing it's upsweep to the surface, your" lead arm" needs to be gently (!!!) moving down to the catch without exerting any force, i.e. don't lean on it! When swimming, the inhalation started as the "stroking arm" does it's upsweep, carries on as the (rear) arm exits the water, and continues until that arm has just gone past the mid-recovery point. At that stage you should start to roll towards the recovering arm as it is about to enter the water. The mantra that needs to be "engraved on your heart" is, "Roll towards the arm going down, and roll away from the arm coming up!". Ideally your "lead arm" needs to be at the catch, ready to start pulling, just as your "rear arm" is about to release it's pressure on the water and make its exit to recovery! Note that by delaying your inhalation until the stroking arm starts it's upsweep, you haven't got a lead arm in any "useful" position, its just gently moving down to the catch - so there's nothing to lean on and collapse, with its consequent scissor-kicking and momentary loss of posture as you turn your head for inhalation!!! The upsweep to the surface of the rear arm is probably the most powerful part of the underwater arm action - so you can be confident that you will be moving at a good pace and have little trouble in starting the inhalation. It's all about confidence really, something that comes from knowing from past experiments, what you can expect to happen! You can also reduce any tendency of "scissor-kicking", by concentrating on keeping a "tight" flutter kick particularly as you turn your head for inhalation. I think a lot of swimmers tend to kick too deeply producing a lot of drag, so experiment with a more narrow kicking action, and really think about brushing those big toes together as the feet pass each other! A slight knee bend as each leg is nearly at the end of it's downbeat, followed by the lower leg flicking down and simultaneously the thigh moving back upwards starting the upbeat, can give a rolling or undulatory leg action which can aid propulsion (make's the leg action more "fish-like"! ). Just remember that the kick upbeat needs to be done with a straight leg, otherwise the back of the lower leg will (if the knee is still bent) be moving against the direction of motion -Drag! While swimming, keep your head as still as you possibly can, despite the rest of the body rolling first one way and then the other - the head is the "steering wheel" of the body - so only turn the head for inhalation! Finally, when you roll, keep the torso as a "solid" unit, so that the legs kick in a plane at right angles to the torso - there is a very good reason for that!" You can find more info here: http://www.swimsmoothforum.com/viewtopic.php?t=1800