A study of starts

Swimming Technique, Oct-Dec 2002 by Tanner, Dave

How much time does a swimmer lose when starting from the deck or pushing off from the wall instead of diving from a starting block?

Last year the National Federation of State High School Associations amended the rule concerning minimum pool depth for racing dives. In pools with less than four feet of water under the blocks, high school races must start from the deck or from within the watr. In Masters swimming, while there is no minimum depth specified for starts, many individuals-particularly those over 75--choose to specified for start from the deck or push off from the wall.

The obvious question, then, is: "How much time does a swimmer lose if the start is not from a block?"

To answer this question, the Councilman Center for the Science of Swimming conducted a simple experiment. We filmed 21 swimmers performing 15 freestyle starts each. Five starts were performed from a standard starting block, five from the deck and five from a push-off. The order of the starts was varied to control for the effects of learning and fatigue.

We used a Colorado Infinity start system and a Canon digital camera to measure the time from the strobe flash until the swimmer's head crossed a line 10 meters from the starting point. Times were measured from the digital recording to the nearest 1/30 of a second.

There were 10 women and 11 men in the study, ranging in age from 13 to 23 years old, with their best 50-yard freestyle times between 20 and 31 seconds. (Breaststroke and butterfly were not measured. We do not believe the results for those strokes would differ from freestyle.)

The results were surprising:

* When comparing the block start to a deck start, the average difference was 0.51 seconds, with a range of 0.40 to 0.62 sec. The results were not related to sex, age, height, weight or best 50 time.

* When comparing the block start to a start from within the water, the average difference was 1.07 seconds, with a range of 0.92 to 1.22. Again, the results were not related to any of the aforementioned variables.

What this means is that it doesn't make any difference who you are or how fast you swim a 50. The results are clear: you can expect to be about a half-second slower from the deck than from the blocks, and about one second slower when starting from within the water.

By Dave Tanner, PhD

Dave Tanner, Ph.D., works for the Counsilman Center for the Science of Swimming.