Speed in the water is the goal of the world-class
swimmers who will journey to Athens this summer. Along with all of
their efforts in preparing for the experience of a lifetime is the
expectation that the Olympic pool will possess all of the qualities
needed to maximize their efforts.
What makes water fast? I believe there are seven
factors that must exist to maximize the performance of speed swimmers.
These factors are not prioritized; however, some are more essential
than others.
Chemical balance. The
pool water must not be chemically aggressive to the degree that itês so
irritating to the mucous membranes of the sinus, mouth and eyes
(goggles can leak) that the sensation will distract an athlete and
affect his or her concentration. Ideally, the water should have a free
chlorine level of .5 to 1.0 ppm and a pH of 7.2 to 7.4 with an
oxidation reduction potential of approximately 750 millivolts.
In some pools, these values are created with a
primary or secondary treatment of the water with corna discharge ozone,
bromine or ultra-violet exposure. In the final analysis, pool water
must meet the quality standards of the local jurisdictional health
agency.
Clarity.Pool
water must be clear so that swimmers have excellent underwater vision.
Turbid water can be a distraction and is therefore undesirable. Clarity
is the result of efficient filtration. Particle sizes greater than 15
microns must be removed from the water through the use of screens, a
filter media and by chemical oxidation caused by hypochlorous acid,
hypobromous acid, ozone, ultraviolet light, etc. Water must have a
turbidity level that does not exceed 0.5 nephelometer turbidity units.
Temperature.Swimmers
must be comfortable in the water, which means the water temperature
should be approximately 78 degrees Fahrenheit (25.5 degrees Celsius).
At this temperature, the swimmerês body will not overheat at maximum
aerobic effort and stress.
At temperatures much below this level, swimmers
usually complain of stiffening muscles, and the body will burn more
calories to offset the colder skin temperature. At water temperatures
above 80 degrees Fahrenheit (26.6 degrees Celsius), swimmers usually
begin to feel sluggish and tend to experience an undesirable rise in
body temperature during maximum effort.
Controlling water temperature requires an
understanding of the medium as a heat sink. Quiescent water will
develop a thermocline with a layer of warm water above a colder mass
below. With different types of supply inlet systems ® wall or floor -
the warm layer will be affected differently.
A crowded indoor spectator gallery of 5,000 to
10,000 people can change the dynamics of the air temperature/water
temperature relationship. When cooling systems are activated for
spectators, pool water temperature and evaporation rates may be
impacted. For these reasons, the system should be engineered for
best-case water temperature control and then tested during swimming
meets to ascertain the effectiveness of controlling water temperature.
Visibility.Good
underwater visibility is the result of exceptional water clarity and
the light level above the swimming pool. FINA stipulates a minimum
600 lux at the turning ends, while the NCAA requires 100-foot candles.
Higher light levels will enhance the field of competition. At these
light levels and with a white field and black markings on the pool
interior, visibility will be satisfactory for almost all swimmers.
Water depth will affect the reflective brilliance
of the pool interior. The deeper the water, the less light reaches the
white reflective surface, which in turn reflects less light into the
medium. The minimum light levels listed by FINA and the NCAA, in water
of minimum championship depths of 2 meters and 7 feet respectively,
will provide satisfactory visibility assuming the light sources are
correctly located.
Direct illumination from above is recommended with
fixtures located directly over the water surface. (Indirect lighting
using reflective light bounced off the ceiling is not recommended.)
With the overhead light source directed perpendicular to the water
surface, light will penetrate the water medium most efficiently and
reflect off the white pool interior.
Underwater lights will increase the light level
under the water surface, and will also reflect off the white interior.
This, with overhead light, will create an ideally illuminated medium
through which swimmers will race. (Itês important to note that the use
of underwater robot cameras using a wide-angle lens and propelled along
the bottom under the racing swimmer may be affected by the permanent
wall mounted lights. As this technology develops, collateral influences
will have to be analyzed.)
The choice of light fixtures should be based upon
several considerations. Metal halide is most often selected for
overhead fixtures, while quartz lamps are preferred for underwater
lights. These lamps produce a white light that is preferred for
competition. Designers and owners have experimented with high-pressure
sodium, but the light spectrum creates some objectionable effects in
the form of reflected glare on the water surface and a diminished
degree of illumination below the surface.
Subsurface turbulence.It
is believed by many that subsurface turbulence can inhibit the forward
motion of a swimmer. This turbulence can be caused by water currents
from the poolês recirculation system. These currents seem to vary
depending upon the type and location of the inlets. Currents that are
the result of circulation flow can be a problem if they exist in the
racecourse. Of greater interest is the theory of rebound turbulence ®
created by swimmers at the surface ® which many believe reaches the
bottom of the tank, rebounds to the surface and interferes with the
forward progress of swimmers. If of sufficient energy and water mass,
this turbulence can reduce the propulsive forces generated by the
swimmer.
To date, there have been no empirical studies
conducted to identify the amount and nature of the rebound turbulence
that occurs when swimmers race in a pool, or what influence various
pool depths have on that turbulence. The minimum depths of two meters
stipulated for championship competition, especially for the Olympics
and World Championships, are sufficient to minimize any subsurface
turbulence that may negatively affect the swimmers at the surface above.
Surface turbulence.The
effect of the water surface on 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 understanding that led to the development of floating lane
dividers and subsequently to the wave quelling designs that are used
today. Floating lane lines absorb wave energy created in each lane by
swimmers and contain any surface energy that is not absorbed within the
lane. The primary benefit of contemporary lane lines is that they
isolate the turbulence in one lane and prevent it from crossing into
adjacent lanes.
To a lesser degree, surface turbulence created
inside the lane by the swimmer must be dissipated. The speed of the
swimmer is not impeded by the residual surface turbulence until he or
she swims back through the lane. As a result, the swimmer experiences
greater impedance during 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 to achieve equilibrium from the last surface
agitation.
This phenomenon affects short-course races
differently than long-course races. Because of the shorter time frame,
the water is -rougher" for the duration of a multi-length race in a
short course than it is in a long course. Itês difficult to apply a
factor to the difference because other influences impact the issue,
such as the number of turns and push-offs, and the possible rest or
stimulation the turns provide the swimmer and the proximity of swimmers
in adjacent lanes.
Psychological influence.Psychological
impact is a subjective variable that influences all athletes in a
positive or negative way at the start of a race. While a swimmerês
mental attitude is most affected by his or her coach, plus the
swimmerês preparation for the event, there are things that natatorium
designers can do to influence the excitement and adrenalin level of the
athletes. Architects should be educated about the experience of the
competitors. This includes identifying psychological impact points,
including the locker room environment, the first entry into the
natatorium, the warm-up routine, the rubdown, and the sounds and smells
he or she experiences as more athletes arrive.
As the time of the event draws closer, there are
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.
Time itself is a stimulant, so the awareness and
communication of time is important. Clocks should be synchronized and
located throughout the natatorium, locker rooms and support spaces.
For Olympic and world-class competition, a ready
room will be provided. The location, design and appearance of this room
can be a factor in motivating swimmers, as is the time spent in the
room before the athletes are led out to their stations on deck before
moving to the starting blocks.
These micro-stimuli affect an athlete as he or she
progresses through the emotional and physical climax of the race, but
there are also macro-stimuli created by the scale of the facility, the
spectator noise, which becomes a part of the experience and can be a
major influence. The pre- and post-race ceremonies, plus the total
pageantry of a world-class championship will have an impact on the
athletes ® sometimes for the better and, in some cases, for the worse.
If all of the environmental stimuli conditions come
together to help produce record-breaking times, and even more
important, personal-best times for those who do not win, the pool will
be known as a -fast pool." Such recognition, based upon performance, is
the goal of competitive venue pool designers.