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Masters Swimming 101

How do I use the pace clock?

Jim Harper | December 4, 2012

This article is part of the Masters Swimming 101 series

A related question would be: Why are swimmers so obsessed with time? You'll find out, my friend, in due time.

So, what is your time for a 100? Answer that question, and you are halfway to speaking Swimmerese.

The clock is a true frenemy—a friend and an enemy. It never lies, but sometimes you wish it would. Because the clock never stops, you need to break it into manageable parts. Get your math cap on, because your coach may give you some intense, clock-based instructions for a set, such as:

“5 x 200s descend on the 4:30, negative split #5. Leaving on the top.”

Got it?

Here are some terms to help you translate Swimmerese and Clockspeak:

The top

The beginning of a minute (the 12 on a clock face), shown as either 0 or 60 on a traditional swimming pace clock, also called a sweep clock, as the hands sweep around the face. Seen as :00 on a digital clock. Stated as “leaving on the top” or “on the 60.”

The bottom

Again, on a traditional clock face, the bottom is actually the middle of a minute, where the number 6 is, which is the 30 on a sweep clock and :30 on a digital clock. Stated as “leaving on the bottom” or “on the 30.”

5 (or 10) seconds apart

The time to wait after one swimmer leaves the wall, before you leave. Watch the clock for your cue to push off.

Repetition

The number of swims within a set. In 5 x 200s, 5 is the repetition—you'll be swimming 200 yards, 5 times, on an interval.

Interval

The repetition of a constant, given amount of time, indicating when you should leave the wall. Stated as an amount of time, such as “on the 4:30.” This is the amount of time you have to both swim and rest before leaving for the next repetition in the set. In the 5 x 200s on the 4:30 example, you'll leave on the top, swim 200 yards, then rest for the remainder of time left in that 4 minutes and 30 seconds, at which time you will push off and swim the next repetition. If you “miss your interval,” that means it took you longer than 4 minutes and 30 seconds to swim the 200.

Rest interval

Sometimes coaches will give a rest interval, or RI. This is a little easier to understand—and easier to swim. If your RI is 30 seconds, then you get 30 seconds rest after each repetition—no matter how slow or fast you swam it. Some coaches do not use RIs because it does not encourage increased effort. In other words, if you know you are going to get a set amount of rest and won't miss your interval, you may not swim as fast.

Time

The actual number, in minutes and/or seconds, it took for you to swim the repetition. In the 5 x 200s on the 4:30 example, if you swim one of the 200s (the reps) in 3:57, that is your time for that rep. You now have 33 seconds to rest on the wall before pushing off for the next rep (and you'll leave on the bottom for that rep).

Pace

Your swimming speed, based on a time achieved for a given distance. Most commonly expressed per 100 yards, as in “a pace of 1:52.” So if you swim a 200, your pace would be expressed in the approximate amount of time it takes for you to swim 100 yards. If you swim at a pace of 1:52, your time for the 200 would be 3:44.

Build

Accelerating or getting faster within a given rep. So if you were going to build a 200, you would try to start out at a slower or medium pace and increase it each length of the pool, so that you are swimming fast by the end of the rep. Not to be confused with descend.

Descend

Obtaining a faster finishing time on subsequent reps. If you descend that set of 5 x 200s, your times might look like this: 4:02, 4:00, 3:59, 3:57, 3:55.

Negative split

The second half of the repetition is swum faster than the first half. In a single rep—just one of those 200s—a negative split example would be swimming the first 100 in 2:02 and the second 100 in 1:58, for a total time of 4:00.

So using all these new terms, let's translate that “5 x 200s descend on the 4:30, negative split #5. Leaving on the top”

  • Start swimming the first 200 when the clock strikes the 60-second mark. Swim at a comfortable pace, knowing that you have four more reps and each has to be faster that the one before it.
  • You come it at a 4:02 for the first one, rest for 28 seconds and leave again on the bottom, since the interval is 4:30, you will have 28 seconds rest.
  • Repeat the reps in this manner.
  • When you get to number 5, you'll need to not only swim faster to maintain your descend, but you'll need to negative split that rep. To negative split, start steady and look at the clock at the halfway point, then go faster for the second half. So if your time for the last rep is 3:55, a good negative split might be 1:59 for the first 100 and 1:56 for the second.

Experienced swimmers tend to follow the clock religiously, whereas less experienced swimmers tend to follow each other. Use the clock to your advantage and learn how to read it independently. When other swimmers don't know what time it is, you will. 

Here's a group exercise for using the pace clock. 

Masters Swimming 101 Article Series

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What are the basics of pool etiquette?
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What is a typical workout?
Like a good play, a good workout develops in three main acts: the warm-up, the...
Yards and meters
Coaches will give instructions mainly in terms of distance (or yardage) and...
How do I use the pace clock?
A related question would be: Why are swimmers so obsessed with time? You'll...
More lingo you're likely to hear at practice
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How do I learn the four strokes? Why do I want to?
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About the Author—Jim Harper

Jim Harper is an All-American Masters swimmer and coach in Miami who writes about health and nature. He is a frequent contributor to SWIMMER magazine, a columnist for the Biscayne Times, and a member of the Society of Environmental Journalists. 

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