001.007 Pool Length Matters

USA-S sanctioned competition may occur in pools with lengths of 25 yards, 25 meters, or 50 meters.  These pool lengths are named as follows:




Time Unit

25 yards

Short Course Yards



25 meters

Short Course Meters



50 meters

Long Course Meters



SCM swims are rare in USA-S, occurring primarily in Oregon.  National age group records are only maintained for SCY and LCM swims, so we restrict our attention to those.

In subsequent posts we’ll discover that pool length has a significant effect on USA-S age group competition.  Disqualifications are more likely to occur in short course pools than long course pools. It’s more difficult for athletes to qualify for long course championship events because they swim fewer LCM events than SCY events.

Short Course Swims are More Frequent.

As shown in the following pie chart, USA-S has more than twice as many SCY swims as LCM swims.  This is expected since the short course season (September to March) is roughly twice as long as the long course season (April to July) and there are more 25 yard pools than 50 meter pools.

90% of age group athletes compete in at least one SCY event per year while only 45% compete in at least one LCM event per year.  Somewhat surprisingly, only 35% compete in both SCY and LCM events per year.


The fewest age group swims occur in August and September; the most in November and February.  As expected, LCM competition starts in March (end of short course season) and increases in intensity through July/August (end of the long course season.

Younger Athletes Prefer Short Course.

Older athletes are increasingly likely to swim LCM events. This age-related shift is largely to due to age group athletes abandoning the short course.  The unusually small number of SCY swims by 18 year olds is likely due to those athletes transitioning from high school to college during their 18th year. Athletes born after March will swim their final short course season before college as 17 year olds, while those born before April may only swim part of their final short course season before college as 18 year olds.

The next chart plots the percentage of all athletes that compete in a given pool length at a given age.  It provides an instantaneous snapshot of USA-S athlete age and course competition, that is, how many athletes of a given age are currently competing in SCY and LCM meets.  SCY participation peaks at age 10, after which it declines. Total participation peaks at age 12, largely due to an increase in LCM participation from ages 10 to 12. After age 12, SCY and LCM participation both decline significantly while LCM-only participation remains remarkably constant.

Here is the same data normalized by athlete age.  It plots the percentage of athletes of a given age that compete in a given pool length.  The percentage of athletes competing only short course declines with age, from 78% at age 6 to less than 50% above age 14, while the percentage of athletes competing only long course increases with age.

My own anecdotal experience is consistent with these trends.  The demands of high school, starting at age 14, make it difficult for athletes to continue in USA-S during the school year (short course season).  Some participate only in the summer break (long course season) while many leave the sport entirely.