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How do you make a pool fast?

There are seven factors specific to pool design and operation that must exist to maximize the performance of swimmers. They do not exist in any order of priority; however, some are more essential than others.

Indoor Air Quality:   Most people are familiar with the “swimming pool smell” that is encountered when you walk into some indoor pool environments.  It’s that “chlorine” smell that can even be noticed at an entry lobby before you even set eyes on a pool.  That “chlorine” smell is actually chloramines off-gassed from the swimming pool.  They tend to reside close to the water surface which is unfortunate for swimmers, especially competitive ones, as this coincides with the breathing zone.  Highly competitive aquatic athletes are familiar with pushing their bodies aerobically and anaerobically.  And in either state, heavy respiration of chloramine-laden air inhibits performance.  The good news is that with proper air distribution over the surface of the water, removing chloramines at their point of formation, along with the installation of medium pressure UV systems which help maintain chloramine levels to 0.2 parts per million or less through their destruction during the recirculation process, dramatically improves the overall indoor air quality within a natatorium and swimmers’ performances.

Water Clarity: The pool water must be clear so that the swimmer has excellent underwater vision.  Clearly being able to pick up floor markings and wall targets allows for swimmers to time their strokes into their turns and finishes, as well as breaking out from their underwater kicks.  Water clarity largely comes down to maintaining ideal water chemistry and water filtration.  Newer regenerative media filters on the market in the last 10-12 years in the United States are gaining popularity for projects pursuing sustainability as they consume considerably less water than traditional high rate sand filters; however, they also filter down to 1-5 microns compared to sand filters which often only capture particulate down to the 25-50 micron range.  Ideally, the water must have a turbidity level that does not exceed 0.5, measured with a nephelometer.

Temperature: Swimmers must be comfortable in the water which means that the water temperature should be approximately 78 degrees Fahrenheit. At this temperature, swimmers’ bodies will not overheat at maximum effort and stress.   At temperatures much below this level, swimmers will usually complain of stiffening muscles plus the body will be burning more calories to offset the colder skin temperature.  At water temperatures much above 80 degrees, swimmers usually feel sluggish and tend to experience an undesirable rise in body temperature during maximum effort.  While water temperatures in the pool recirculation piping and the pool itself are common, it is important for the designer to also understand the impact on often hundreds, if not thousands, of spectators and their contribution to the conditions within the natatorium.  By their impact on the loading within the space, the pool water can be impacted through changes caused by evaporation.

Visibility:   Good underwater visibility is the product of exceptional water clarity and the light level above the swimming pool.   For the highest level competition pools, some regulatory bodies will require 100-150 foot candles of lighting over the water surface for the entire race course so that the visibility for swimmers as well as a remote viewing audience is satisfactory.  This often requires direct illumination from above utilizing fixtures located directly over the water surface.  With the overhead light source directed perpendicular to the water surface, light will penetrate the water medium and reflect off the white pool interior.   Underwater lights will increase the light level under the water surface not only as a source but it will also enhance the reflected light due to the white interior.     In this manner it will create an ideally illuminated environment for competitions.

Subsurface Turbulence: It has been established that subsurface turbulence can inhibit the forward motion of a swimmer.    Such subsurface  turbulence can  be caused  by water  currents  from  the pool’s recirculation system but  that seems  to be a variable depending  upon the type and location  of the inlets.  Such currents that are the result of circulation flow can be a problem if they exist in the bounded water volume of the race course.  Of greater concern is the presence of rebound turbulence created by the swimmers, more prevalent during their starts and turns while executing underwater dolphin kicks. This swimmer turbulence reaches the floor of the pool and then rebounds off the bottom and returns to the surface in such a way that it interferes with the forward progress of the swimmers.

Surface Turbulence: The  effect  of the water surface  on the forward  progress  has been  recognized  for centuries  by people  who have struggled  to paddle  a canoe  or row a boat through  choppy water.   Swimmers have long been aware of the difficulty of swimming through rough water as compared to a smooth flat surface.  It was this basic understanding that led to the development of floating lane line dividers and subsequently to the wave quelling designs that are used today.  The purpose of these floating  lane lines is to absorb  the wave energy that is created  in each lane  by the swimmer  and  to contain  within that lane  that  energy  which is not  absorbed.    The  primary  benefit  of the  contemporary  lane lines  is to isolate  the  turbulence in one lane and impede  it from crossing into the adjacent  lane.

Of lessor degree is the  dissipation  of surface  turbulence  inside  the lane  where  the swimmer  has created  agitation.   This dissipation continues after the swimmer leaves the relative point in the lane.    The amount of dissipation of surface turbulence varies at any given location relative to all other locations in the lane.   Understandably,  the speed  of the  swimmer  is not impeded  by the  residual  surface  turbulence until  he  or she  swims back  through  the  medium.    (For those who have watched swimming on television narrated by Rowdy Gaines, you are liekly familiar with the importance of getting under the wave as a swimmer executes a turn and pushes off the wall.)  As a result,   the swimmer experiences greater impedance at the first third of each length with the exception of the first length.    Conversely  the  least  impedance  occurs  in the  last  third  of each length, when the surface  has experienced  the longest period of time from the last surface agitation.

Psychological Influence:   Psychological impact is that subjective variable that will influence all athletes in a positive or negative way at the start of the race.   While the mental attitude of the swimmer is largely affected by his or her coach,  plus the preparation for the event,  there are things that the designers  of the natatorium can do to influence the excitement and adrenalin level of the athletes.   Sometimes they enhance the swimmers performance and sometimes they do not.

First, the design architect should educate himself or herself about the actual procedural experience of all the competitors. There are identifiable  psychological impact points in the experience from arrival at the natatorium, through the locker room environment,  the first entry into the  natatorium, the warm-up routine,  and build-up of energy as more and  more athletes  arrive. As the time of the event draws closer, there are special individual behavior patterns that each competitor will carry out.  This usually includes a period of time for seclusion, meditation and concentration.  Privacy may be an empty room, a corner under the stands or simply a towel over the head.

For high end competitions, a ready room is provided.   The location, design and appearance of this room can be a factor in motivating the swimmers; as well as the time spent in the room before the athletes are ceremoniously led out to their stations on deck before moving to the starting blocks and annouced prior to the start of the race.

The above microstimuli  affects the athlete prior to the race.  There are macrostimuli as well that are created  by the scale of the facility,  the spectators who become  a part of the experience, teammates, and the pre-race and post-race  ceremonies.  The total pageantry of high end competitions, especially those at the highest levels, will have an impact on  the  athletes.

If all of the environmental stimuli and  conditions  come  together  to  help  produce record  breaking  times, and even more important, personal  best times for those that do not win, the pool will understandably be known as a “fast pool”.

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