Pool Length Differences in Triathlon Swimming

What’s the difference in pool length?

The length of the pool you swim in has many different effects on how your systems are stressed and how fast you go. This article is contains a detailed commentary describing the differences, and concludes with suggestions on how to incorporate knowledge of pool length to optimize a triathlete’s training plan.

Pool lengths typically come in three distances. There is the 25yard pool (common in the United States), the 25meter pool (common just about everywhere else in the world), and the 50 meter or Olympic-size pool (relatively uncommon just about everywhere as olympic size pools are costly to build and maintain). The swimming world uses abbreviations for these distances: SCY stands for “Short Course Yards”, while “SCM” stands for “Short Course Meters”. Likewise, “LCM” stands for “Long Course Meters”.

So, why does a pool length matter so much? The answer is flip turns and starts. The shorter the pool length, the more flip turns are needed to go the same distance. Also, the ratio of time spent diving into the pool and performing flip turns compared to time spent swimming is higher. For example, your flip turns take up a greater proportion in your race in a 25yard pool versus a 25meter pool because 25yards is shorter than 25 meters. This is very important, because flip turns and starts have the benefit of being faster. You can push off the wall with greater speed than you can swim. In addition, flip turns allow swim specific muscles a momentary pause. This pause allows for a faster recovery compared to continuous swimming.

There are also physiological differences that come into play, particularly when comparing Short Course swimming to Long Course swimming. In a short course pool, even mid-level triathletes are swimming a length in 20 seconds. This is barely enough time to engage the anaerobic system, which isn’t needed much unless the exertion is more than about 15seconds. By the time the anaerobic system gets engaged, you have to do a flip turn, get a momentary rest, and then get to start the next length fresh. Thus, in short course swimming, your raw strength is stressed much more compared to long course.

Conversely, even the best long course swimmers cannot swim lengths at a rate of 30 seconds for very long. At a 30-second continuous hard effort, the anaerobic system has to be your workhorse. Thus, in order to swim well in a long course pool, your ability to hold speed over several minutes (anaerobic endurance) is much more crucial than your flat out speed (raw strength).

So, now that you know the differences between short course and long course swimming, how can they compare? If you have times that you have gone in a short course pool, what can you expect to do in a long course pool? The answer varies based by individual. If you can do flip turns and starts quickly, you will tend to be a better short course swimmer. Or, you will also be a better short course swimmer if you tend to swim fast by the use of raw power rather than endurance or efficiency. Even the best swimmers in the world have a significant variation in how they swim from Short Course to Long Course. However, there is an average conversion factor that I use, as shown in the table below. This may not be exact for everyone, but it will be a good approximation.

Table – Average time conversion factors by pool length.

To give an example using the table above, let’s say your best ever SCY 50 free time is 30 seconds. If you tried to sprint a 50 in an Olympic sized pool, you can expect to swim the distance in around 34.68 seconds (or 30 times 1.156).

Notice the difference between Short course meters and Long course meters is significant even though the unit of measure (meters) is the same. The difference roughly equates to a full second time difference over 50 meters. One reason for the difference is that flip turns and wall push-offs are always faster than raw swimming. Another reason is that when you do a flip turn, you skip the distance to and from the wall, as you only need to get close enough to turn and push off (a difference of about 40 centimeters for most people, which increases if you are tall and decreases if you are short). This small difference adds up. An example will be illustrated using a swimming distance 200 meters. In an LCM pool, you would perform 3 flip turns to go 200 meters, and would be really swimming approximately 197.6 meters (200 – 3 turns x 0.4meters x 2 to/from wall). In a SCM pool, you would perform 7 flip turns to go the same 200meter distance, and thus would really swim 194.4 meters (200 – 7 times 0.4meters x 2 to/from wall). This is a difference of 3.2 meters, or 1.6% of the total swimming distance.

So, why does all this matter to you? It is important because open-water triathlon swimming has no flip turns or resting periods. Thus, training regularly in an Olympic sized pool will provide more open-water specific benefits for most workouts. The exception is that raw speed / sprint workouts can be more beneficial in a short course pool (remember that raw speed is emphasized more in short course compared to long course). If you can find an Olympic sized pool, by all means use it. If one isn’t available and you can swim in a nearby lake, you can mark off a set swimming course using a handheld GPS or measured rope length and use empty milk jugs as marker buoys.

If you cannot swim in a lake or Olympic pool, should you just pack it in and leave triathlons to the pros? Absolutely not! There are many world class swimmers who train most of the year in a short course pool even though their primary races are in a long course pool. To use my own triathlon experience as an example, over 90% of my swimming training was in a 25yard pool.

If a 25yard or 25meter pool is your only option, don’t worry too much about faster flip turns and underwater kicking. You want to be proficient in turns so you don’t hit your head on the wall. Instead, focus more on improving your swimming ability to turn in faster pool times. And, it is okay to skip flip turns altogether and use open turns. Another strategy in a short course pool is to skip the turns altogether by swimming lengths and turning around without your feet ever touching the wall. This is a tremendously challenging workout as it involves constant stopping and starting making it almost impossible to establish a rhythm. If you focus on the swim and not the walls, you can go a long way to eliminate problems with training in a short course pool.

So as you plan your next triathlon season, be aware of the conditions of the pools in which you will be training. You will want to swim in a long course pool whenever possible. However, swimming short course is okay provided you focus on the swimming and not the walls. Also, be aware of the time differences you can expect between the various pool lengths and why they exist. Long course swimming is so much tougher because it stresses the anaerobic system much more than short course swimming does. In addition, long course has less flip turns which equates to less speed. Now you know everything there is to know about the pool length of your favorite facility. Until next time, happy training!

Coach Duane Dobkanize Dobko