One clear fundamental for swimmers to understand is that more efficient swimming can be accomplished in two ways – by decreasing resistance and-or by increasing propulsion.

The first step is to produce as long and as sleek a body position in the water as possible.

For humans, swimming is not a natural act, but we can use nature to help. Fish glide through the water seemingly without effort. Why not imitate them? Are they flat in the water? The only flat fish is a dead fish, so why kill yourself?

The answer is to be on your side, with arms and legs relaxed and extended.

We can also learn from ships. There is a law that, all other factors being equal, the ship with the longest waterline is the fastest. Ships are shaped like fish, especially at the waterline.

Swimmers encounter three types of resistance that affect efficiency. The obvious type is head-on, which happens when a swimmer is on the stomach or back with the head out of the water – full frontal resistance.

Lifting the head raises one end of the body around its center of buoyancy, which by Newton’s Third Law (action and reaction) lowers the other end of the “teeter-totter” and makes forward progress very difficult.

If, instead, the swimmer’s body is on its side, it knifes through the water much more easily.

At the very least, if a swimmer is horizontal in the water, it is necessary that the head be underwater to create less frontal resistance.

A second type of resistance is friction, which is affected by the swimming suit, but more so by body parts that stick out from the “ship” or “fish” during the stroke. Surface tension can be avoided by maximizing being underwater.

The third type of resistance is eddy resistance, the type that sucks dirt onto the back of a van or SUV. To minimize this, the legs and feet must be kept relatively close together in the attempt to form a long waterline.

Using decreased resistance, all good swim strokes incorporate a glide phase so that struggling is reduced, and less effort is needed for aquatic locomotion.

It may seem counter-intuitive or even radical to you at first that swimmers would do better by working at eliminating resistance than by swimming more laps. But it works. I plan to develop this concept in future columns.

A Bluffton resident, Dr. Bob Colyer is an actively retired college professor and coach who has recently published “Swim Better, A Guide to Greater Efficiency for Swimmers & Instructors.”