Originally Posted by
bamboostix2011
In most sports, athletes are aware that they are sweating. They can see the sweat on their skin, and their clothes and hair becomes soaked. Sweat loss varies with the individual and their sport. Some athletes sweat more than others, especially when they are acclimatised to hot conditions. Other factors influencing sweat rates are the environmental conditions (how hot, humid and windy it is) and the intensity of the exercise. The harder the athlete is working, the more heat that their body is producing.
In most sports conditions when the athletes are working hard, scientists tell us to expect sweat rates of 1-1.5 litres per hour.
But these figures apply to athletes exercising on land. What of athletes who exercise in water, such as swimmers, water polo players, water aerobics devotees and lifesavers? Can you sweat when you are fully immersed in water? How can you tell if your body, your hair and your clothes are already wet? Do you need to sweat to lose body heat produced by exercise - or is your body sufficiently cooled by the water it is swimming in? These are some of the great mysteries of life, and in attempting to find an answer to these, we actually found some other unsolved questions: Why do you want to go to the toilet as soon as you get into a pool? And do swimmers pee in the pool? The original purpose of our inquiries was to see if dehydration was a real issue for swimmers and other aquatic athletes, and how well our current group of athletes looked after their fluid needs in a typical exercise session.
The problems of dehydration in competition are likely to be a problem only to open water swimmers. But that's another story. For our study we confined ourselves to the training sessions undertaken by elite swimmers - often 1-2 hours of high intensity work. And we conducted our study in Atlanta in 1995 during the camp preceding the Pan Pacific Games. Training was carried out in an indoor pool that was not air conditioned. Therefore, although the swimmers were protected from direct sunlight, they did their training in hot (300C) and humid (60% relative humidity) conditions. The pool temperature was 290C - perhaps a degree or so hotter than many competition pools. We estimated sweat losses, dehydration and fluid intake with a technique that the AIS Nutrition Department has used to conduct a number of fluid balance studies with elite sports people. We weighed our athletes with accurate scales before a training session, and then again on completion of the session. The change in body mass was said to represent the fluid deficit produced during the training session, with % dehydration being this deficit divided by initial body mass.
We also monitored fluid "comings and goings" during the session. Drink bottles were weighed on small scales at the beginning of training and at the end, to estimate the amount of fluid consumed by the swimmer during the session. We also implored any athlete who needed to make a visit to the bathroom, to towel off, weigh, go to the bathroom, reweigh, and then get back into the pool.
By adding fluid intake, and subtracting the "losses" due to bathroom visits, we were able to estimate the total weight change, and thus sweat loss, during a training session. These calculations were done for 13 training sessions and a total of 295 observations. Since swimmers had done different work and different mileage in the pool, we decided to express the changes per kilometre of swimming. We also looked at the different types of sessions undertaken. (aerobic, anaerobic threshold, maximal oxygen consumption, race pace/speed work) to see if this influenced sweat losses and fluid intake measurements.
The results are summarised in the table below:
The results showed, that swimmers lost about 600ml of sweat during their typical training session (mean distance = 4km, mean time = approximately 1 hour of training). We found that male swimmers sweated more and drank more than female swimmers. And we saw that the "sweatiest" sessions were ones based on anaerobic threshold training. Not only did these sessions increase the rate of sweat loss, but the swimmers seemed less successful in drinking enough fluid to replace their losses.
Of course, we acknowledge that there are sources of error in this study method. We could not be sure that we accounted for all urine losses. In fact we noticed that the swimmers were much more likely to "hop out" for a visit during a training session than any other athletes that we have studied. Maybe this is due to the fact that they remain in general fluid balance, and sometimes even drink more fluid than they are sweating.
In summary, our study showed that swimmers do sweat, although at rates that are lower than land-trained athletes. And we showed that swimmers are able to replace their fluid losses during the session by drinking from water bottles kept at the end of the pool. These results perhaps represent the optimal situation. After all this was the national swim team, who are motivated and well educated. What's more, sports drink and water are made up at every session for them, and coaches remind them to bring their drink bottles to session and to drink between sets. It doesn't come more easy than that.
so inshort sington gyud ta bisan sa underwater activity hehe......
Re: Sington ba ta ug magswimming?
or kung matulog ba sad ang isda... 
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