Distance Per Stroke and Related Pursuits

author : garyhallsr

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How important is it to decrease your stroke count?

By Gary Hall Sr.
The Race Club

There is much confusion surrounding the terms DPS (distance per stroke), SPL (Strokes per length or stroke count) and Stroke Rate (number of arm strokes taken per minute) and their relative importance. In particular, there are many coaches today that emphasize one or more of these as being very desirable, when they may not always be.

None of them necessarily have anything to do with efficiency or speed.

Going to extremes

For example, a swimmer can simply hold her arm straight in front and kick on her side, taking a stroke in the middle of the pool, and turning onto the other side until she reaches the end of the 25-yard pool. That is tremendous DPS (distance per stroke): 12.5 yards to be exact! It is also tremendous SPL (strokes per length): one! Swimming efficiency may also be good while doing this method, however, the stroke rate (perhaps three strokes per minute) and the speed are awful.

She could also swim the same 25 yards of freestyle in the same amount of time, clenching her fists. This causes a high stroke rate: more than 90 strokes per minute; high SPL (strokes per length): about 33 strokes; and very poor DPS (distance per stroke): less than 1 yard. In this case, both efficiency and speed may be poor.

Efficiency

As with a car, where efficiency is measured in miles per gallon, the efficiency of a swimmer is measured in meters swum per calories expended. Being efficient doesn't, by itself, win races. Speed does. One's velocity in the water is related to the propulsive power one can generate, minus the frontal drag forces that are imposed while swimming.

In order to attain and maintain the highest velocity possible in the water, one needs to achieve both speed and efficiency. The question is, what type of freestyle will give you the best of each? The answer to that depends greatly on how strong the legs are.

Velocity

Great kickers have the potential to achieve high DPS (distance per stroke), while maintaining high speed and efficiency. Poor kickers do not. So if one has a poor kick, one needs to sacrifice DPS (distance per stroke) in favor of increased stroke rate and SPL (strokes per length) in order to attain higher velocity. Don't fall into the trap of equating high DPS to the best technique. It may not match for you. Great swimmers tend to keep their DPS similar whether swimming fast or slow. In order to do that, they increase their stroke rate, while pulling and kicking with more effort.

The easiest way to measure your stroke rate is to buy a stopwatch (for example, an Ultrak 400 or Finis 3X-100M watch) that has the mode built into it. Have someone start the watch on the hand entry and stop it on the third successive entry with the opposite hand and you will have your estimated stroke rate in strokes per minute. Stroke rates can and do change quickly as you tire, so it is better to check them more often with a watch rather than counting a lot of strokes and dividing by the minutes you swim, which gives you an average over that time.

Yours in swimming,

Gary Sr.
The Race Club

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date: March 18, 2011