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 Sportscience list can be viewed on our forum page. When the page has loaded, search for messages since Dec 23 1997 containing the word "wrestler". Or use the search form for the Sportscience list on our Net Search pages.
Clinical background by Tim Noakes.
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.
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.
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.