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WRESTLERS' DEATHS
Mailing lists in December
were buzzing with news of the death of three wrestlers. Apparently
they were exercising in rubber suits to sweat off enough weight to
get themselves into a lighter weight class.
Heat and dehydration were probably the
factors responsible for the deaths. Muscle fibers damaged by heat
release potassium ions into the blood. The kidneys normally help
remove the potassium, but with dehydration, blood stops passing
through the kidneys. So the potassium builds up to such a high
concentration that it stops the heart beating.
Three deaths in quick succession make
you wonder if there was a common factor. The media latched onto the
idea that it might be creatine, a food supplement that increases
muscle mass with training. More muscle mass would mean more body
weight for a wrestler to lose. But it's suspected that only one
wrestler was taking creatine. If drugs were involved, there are
several candidates. Diuretics are used to decrease body weight by
increasing urine production, and in the process they can push up
blood potassium. Steroid hormones may also increase blood potassium
by damaging the kidneys.
Drugs or not, exercising in the heat
in a dehydrated state is asking for trouble. The American College of
Sports Medicine has a position stand in which it discourages use of
rubber suits and other dangerous methods of weight loss for wrestlers
(see Medicine and Science in Sports and Exercise, 28(6), ix-xii,
1996). Everyone in wrestling should know about this position
stand.
Messages on this topic sent to the
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the word "wrestler". Or use the
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Sportscience list on our Net Search pages.
Clinical background by Tim
Noakes.
SLAP-SKATE UPDATE
The slap-skates you read
about in a News article on
these pages last year are now revolutionizing skating. Every world
record will probably be broken this season. Several are already
smashed. Chalk one up for the lab guys in the Netherlands. They
combined expertise in biomechanics, physiology, and experience as
skaters to create a near-revolution in a sport that has been
unchanged for decades.
The Ferret has heard that the
Norwegians tried to revolutionize speedskating with an "aerodynamic"
monstrosity that looked like a chicken suit with a tail a few years
back. This closely guarded secret may explain why the Norwegians
haven't been very creative with regards to technical innovation in
sport: they are still recovering. Well, to be fair, they lead the way
with ski-waxing technology.
Contributed by Stephen
Seiler.
FREEZING FIELD TESTS
Want to measure oxygen
consumption at sub-zero temperatures? Read this report just in from
Stephen Seiler.
Over the last year we have made two
one-day, all-or-nothing trips to the mountains to make metabolic
measurements of elite alpine and Telemark skiers under simulated race
conditions. We used the new Metamax portable ergospirometry system.
Temperatures as low as -15°C, high relative wind speeds,
altitude and temperature changes during the descent, and physical
stress on the instrument box (high-speed contact between system
back-pack and slalom gates!) were among the field conditions to be
overcome. We were very satisfied with the results. Stability of the
gas and volume calibrations was excellent.
During recent testing at -15°C we
lost gas data from 3 runs, possibly due to condensation or mucous
freezing in the narrow gas-sampling tube. As much of our field
testing here in Norway is focused on skiers in very cold conditions,
this problem must be eliminated. However, our experience to date is
that the Metamax system will work where temperature stability has
rendered other portable VO2 systems unusable. And it is constructed
for physical punishment above and beyond any reasonable expectations
for a high-precision instrument. See the validity and reliability
study by Schulz et al., Int. J. Sports Med. 18:1-4, 1997 for more
information on this system.
As for the data? Well, skiing downhill
may be gravity assisted, but it is no free ride, metabolically.
RELIABLE ROWING
According to a paper in the
pipeline, trained rowers vary their performance time typically by
only half a percent when they do repeated 2000-m tests on a Concept
II rowing ergometer. The Ferret's informants claim that this sets a
new record for reliability. In the more usual tests of cyclists or
runners, the variation is 1-2% or more, depending on the test
protocol and type of ergometer.
It's great news for researchers
interested in factors that affect physical performance in events
lasting five minutes or so. It means you can do a study with a
reasonable number of subjects and expect to detect those small
changes in performance that make all the difference to an elite
athlete. And the findings on trained rowers will almost certainly
apply to trained athletes in cycling, running, and other
high-intensity sports. Now we need highly reliable performance tests
for longer endurance events and for events of a minute or less.
REVIEW
OF SPORT VISION
It's a pity if you can't access the
Journal of Physical Education, Recreation and Dance, because you'll
miss an excellent plain-language review by Knudson and Kluka on
limitations and enhancements of vision in sport. There's lots of
research-based advice for sports such as basketball, golf, tennis,
volleyball, and gymnastics. For example, "The cue watch the ball
hit your bat could adversely affect performance by encouraging
exaggerated head motion and less visual attention earlier in the
trajectory of the ball. The cue use your eyes to lock onto the
ball as it is released might be more appropriate." After reading
this review, the Ferret is also much more sympathetic towards
officials who miss the call.
Knudson, D, Kluka, D.A. (1997). The impact of vision and
vision training on sport performance. Journal of Physical Education,
Recreation and Dance, 68(4), 17-24.
See also the Sportscience News article in May-June 1997 on
a
visual skills program for hockey players.
The
review is now available
here.
