Fluid hydrodynamics plays a role in a swimmer's overall performance, because the forces produced in and by water can either increase or decrease a swimmer's velocity. By educating yourself on the behavior of liquids and their effects on objects, and the four principles of hydrodynamics, you can learn to swim more proficiently and optimize your results.
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Swimmers who successfully master "lift" understand that using it helps them create a "sculling" effect, which in turn, produces more torque and power. Lift is the perpendicular force relative to the working arm and comes into play in freestyle propulsion, wherein a swimmer performs a constant windmill-like arm movement to propel himself forward. Sculling forces help swimmers conserve more energy that can be used at a later time.
Center of Buoyancy
You can learn how to use buoyancy to your advantage to sharpen your swimming exercises, or techniques. Focus on your "center of buoyancy" -- identify the region of your sternum that allows maximum balance while propelling yourself through water -- to swim more proficiently by pressing your upper chest into the water. In turn, this brings your legs closer together, establishes balance and reduces drag as you propel yourself forward. You can work with this concept to improve your breaststroke, backstroke and crawl.
Swimming coaches stress the importance of using lift and drag. Propulsion is the force generated by your arms and legs to propel yourself forward, and uses lift and drag to maximize velocity in freestyle swimming. Pull backward with your hands curved and at right angles to the pulling direction to maximize your distance per stroke. You should notice a sweeping motion as you propel forward, since propulsion utilizes as much drag and lift resistance as possible relative to the swimmer's hand positions.
As you propel yourself through the water using both your arms and legs, you will also use larger muscle groups such as your chest, your upper and lower back muscles, and your shoulders, to generate more torque and power and significantly decrease the amount of resistance from drag. As you perform a pushing motion upon completing your arm movement, you will notice less restriction by the force of drag, allowing you to perform smoother stroke movements.