THE HEAT INDEX PUTS THE HEAT ON US!
Competition has been suspended or cancelled on two days
during December 2008 and January 2009. On those two days,
the Heat Index QMA uses to determine whether it is safe
for competition to continue rose past the limits set
down in our policy. So, the QMA policy regarding heat
and the safety of our members is well and truly in the
spotlight.
Here are a few questions and answers about the Heat
Index:
Q. What is the Heat Index (HI)?
A. The HI is a measure that combines the effects of both
temperature and humidity into one figure. We all know
that high humidity reduces our ability to lose our
internal heat by sweating so the HI taking into account
not only the temperature but the humidity is a sensible
step. The Heat Index, or its other name Apparent Temperature,
is a widely recognised measure of heat stress.
Q. How is the HI calculated?
A. The HI can be calculated by formula or by reference
to tables with temperature on one axis and humidity
on the other. For QMA competitions we use an electronic
instrument which displays the HI directly. The temperature
and humidity readings it uses are sent by wireless
from a remote sensor placed in the shade near the track.
Q. Where do the “competition cancellation” HI
levels come from?
A. The levels are derived from data provided by the United
States government’s National Weather Service. Their
data states that when the HI gets over 41°C that “Sunstroke,
heat cramps, and heat exhaustion likely, and heat stroke
possible.” They point out, however, that the HI
values they tabulate apply to shade and light winds and
that the HI values can be up to 9°C higher in direct
sunlight. To establish a direct sunlight level that does
not exceed 41°C we need to have a lower value when
reading the HI in the shade. QMA have chosen to deduct
6°C from this 41°C value on the basis that our
competitions are usually over by 11:00am - so our competition
cancellation reading is 35°C.
Q. Is there any other measure that confirms the HI competition
cancellation levels?
A. Yes! Sports Medicine Australia recommend that when
another measure called the Wet Bulb Globe Temperature
(WBGT) reaches 28°C, all competition should be suspended.
The Australian Bureau of Meteorology (BOM) has a chart
to estimate the WBGT for direct sunlight and light winds
given inputs of temperature and humidity. For a recent
competition meet (January 17th 2009) the measured HI
was just hovering on the level where cancellation of
the meet would take place. The BOM chart estimated that,
for the general 9:00am conditions in Brisbane on that
morning, the WBGT was 30°C – above the Sports
Medicine Australia recommended competition suspension
level. The HI measure, therefore, is confirmed by the
WBGT measure and this gives assurance that the HI can
be used for heat stress measurement.
Q. I’ve been competing in Queensland for years
- why should these levels apply to me if I’m well
acclimatized?
A. It may be true that some “heat hardened” competitors
won’t feel that the conditions warrant cancellation
of competition. QMA have no way of knowing, however,
how acclimatized or fit our members may be who attend
a particular competition. In particular, we don’t
know how well Visitors are able to cope with severe heat
conditions. The bottom line is that we have a Duty of
Care to all competitors, officials, volunteers and Visitors
and it is prudent to adopt a cautious approach.
Q. I’m a Thrower – why can’t
I keep going?
A. Throwers have the luxury of sitting down in the shade
between throws and the heat load on them is far less
than for a track athlete. But even some of our stronger,
fit throwers can be badly affected by heat and this was
the case at the Weight Pentathlon in March 2008. In addition,
what about the officials out in the sector for throw
after throw helping with the measuring. Again, QMA needs
to take a conservative approach and ensure that no-one,
thrower or official is in danger from heat stress. So,
when the HI reaches the trigger levels for cancellation
of a competition, it will apply to all events.
Q. Why don’t we compete at night as they
do in some other States?
A. This would obviously solve the problems with heat.
QMA have found, however, that members vote with their
feet and our current occasional night meets are very
poorly attended. The vast majority of QMA’s members
prefer morning competition.
Q. Why don’t we compete in Winter when it’s
cooler?
A. Again, as far as temperature goes, this would be much
more pleasant. The Australian Championships are at the
end of the summer season and for those who are keen to
compete at this level, the current timing of competition
is ideal. There are many who never wish to compete at
such a level and the concept of a winter competition
is something that the QMA may wish to consider for future
years.
Q. Competition has not been suspended - does that mean
it is OK for me to continue even if I feel stressed?
A. If you feel stressed than stop immediately! For various
reasons you may feel the heat more than you usually do
so stop, have a rest, cool off under a shower, have a
cool drink or whatever is necessary to get you feeling
OK again. Don't be tempted to soldier on because your
opponents have. Heat Stress can be dangerous so look
after yourself and live to compete another day.
Q. I often compete at a venue where they don't have
a Heat Monitor, what precautions should I take to avoid
Heat Stress?
A. Make sure you are well hydrated by drinking an adequate
amount of fluids. If you are thirsty during a competition
you are already dehydrated and your performance has suffered.
On top of that the old Slip-Slop-Slap is very good advice
and keep in the shade as much as possible. The bottom
line is that your health is your responsibility - if
you don't feel good because of the heat then STOP competing
and cool off.
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