Becoming a more efficient swimmer involves a reduction in resistance and-or an increase in propulsive force. It is the latter that most swimmers want to work on, even though it is harder to accomplish than making their bodies long and sleek.

Both factors in efficiency are greatly influenced by improvement in following Newton’s Third Law of Motion – every action has an equal and opposite reaction.

Swinging one’s arm(s) wide in recovering between propulsive efforts, or propulsive efforts made from one side to the other (crossing over the midline of the body to start stroking) are not efficient. These movements result in a corresponding swing of the legs in the opposite direction, a back-and-forth motion that greatly increases resistance.

Similarly, if the swimmer pushes down on the water, the body goes up in reaction -and down by gravity – instead of forward from a force directed toward the feet.

Therefore, alternating arm strokes need to stay close to the midline of the body on both stroke and recovery, and double-arm strokes need to stay symmetrical to keep the propulsion balanced and resistance reduced.

Newton’s Second Law of Motion is even more vital for efficient propulsion because it tells us (without getting too technical) that acceleration depends on the amount, direction and length of time a force is applied. The first is obvious, the second is covered above, and the third is similar to how long you can put your foot on the accelerator.

The simplest advice I can give in order to follow these laws is to keep your elbow above your hand throughout the stroke, inverted when swimming on the back.

Good swimmers can clearly be seen doing this above the water for recovery, but it is even more vital under water. With a dropped elbow, the only surface you can use against the water for propulsion is the back of your upper arm.

However, with a high elbow from a lifted upper arm turned inward, you can use not only your hand, but also the insides of both your upper and lower arm to exert a propulsive force against the water.

Using your whole arm (or arms) and applying the greatest surface area possible against the water toward your toes will propel you forward more easily and more efficiently with less struggle and wasted energy.

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