Fundamentals for reducing resistive drag

Water is a 1000 times more dense than air, so when the body moves forward through it, the water resists its movement with a force substantially greater than the resistance of air. That force is resistive drag. Swimmers will accelerate forward so long as the propulsive forces they apply are greater than the resistive drag forces holding them back. They encounter resistive drag as they move forward because they must actually push streams of water molecules out of their way to open a hole in the water for the body to pass through. The resistive drag is directly proportional to the turbulence they create as they swim down the pool and is determined by four factors:

• the space swimmers take up in the water,
• the shape they present to the water,
• limb movements that push water forward instead of backward, and
• the friction between the body and the streams of water that come in contact with it.

Below is a list of fundamental statements that apply to reducing water resistance.

• Maintain lateral alignment in the front crawl and backstroke by roteting the body around its longitudinal axis in synchronization with the downwardand upward movements of the arms. The entire body must rotate, from head to toes, as an entire unit. Never try to maintain one part - the hips or legs - in a flat position while the arms and shoulders are moving up and down.
• To reduce form drag (product of the two first factors that determine resistive drag), keep the head in the line with the trunk whenever possible. The only time the head should be out of alignment is when it is lifted out of the water for a breath in the butterfly and breaststroke. The head should remain aligned with the trunk when it is rotated toward the side to breath in the front crawl stroke.
• Maintain horizontal alignmentby swimming through the water, not over it. Any efforts to elevate the head and shoulders above the water will only increaseform and wave drag. The exceptions are the butterfly and breaststroke, in which swimmers should raise the head and shoulders out of the water to breathe. Even swimmers in these strokes should maintain a horizontal body position during the propulsive phases of the armstroke and kick, however, at least when it is possible to do so.
• Body undulation is essential to propulsion in the butterfly and, to a lesser extent, in the breaststroke, but it should not be excessive. Swimmers should raise the head and shoulders out of the water sufficiently to reduce resistive drag during breathing and, in the case of butterfly, to allow arm recovery without forward draging. Undulation should take place at or just below the surface to a position above the surface where the breath is taken. Swimmers should not push the body underwater simply to increase range of undulation. Excessively pushing the body downward will only increase form drag.
• All entry and recovery movements of the arm and legs should be 'soft' and smooth to reduce pushing drag. Where possible, keep the limbs within the cross sectional area of the body as they enter the water, and slide them forward through the water with the smallest and most tapered surfaces, the fingertips, facing forward.
• The first portions of all underwater armstrokes, the downsweep and outsweep, are not propulsive. Therefore, they should be excecuted softly and smoothly to keep pushing drag to a minimum. Lead with the smallest and most tapered surfaces of the hands and arms, the fingertips, when sliding them down and out during the downsweeps and outsweeps of all four competitive strokes.
• Don't kick any deeper, higher, or wider than necessary to produce an optimum amount of propulsive force. Kicks that are excessively wide and deep will increase pushing drag and may disrupt horizontal and lateral alignment. Kicking upward excessively will push the body downward. Where possible, maintain an optimum leg spread that keeps the legs within the cross sectional area of the torso in both lateral and vertical directions.
• Don't pull the legs into a flexed position in the flutter and dolphin kicks. The legs should only travel upward to body level during the upbeat of the flutter and dolphin kicks (downbeat in the backstroke). The remainder of their upward motion should take place during subsequent downbeat (upbeat in the backstroke). Leg flexion at this time may make it appear that the upbeat is still underway, but that flexion should occur as the thighs are actually pushing downward. At that time, the water underneath the relaxed lower legs will push the body upward into a flexed position until the legs start to extend at the knees. Use the minimum amount of muscular effort needed to flex the legs forward during leg recovery in the breaststroke.