Talk about a feisty debut. The 10km marathon swim brought us leg-pulling and tangled weeds in the women’s event yesterday. Today in the men’s, Britain’s David Davies claimed he felt violated after being swum all over by other competitors, before becoming delusional through exhaustion, swimming the wrong way and missing out on gold to claim silver. The title went to Holland’s Maarten van der Weijden, who showed great survival instinct to grab gold. Maarten overcame leukaemia in 2001 and returned to swimming in 2003 so to add to his 25km world championship earlier this year with Olympic gold is a fantastic achievement for the giant Dutchman.

Earlier in the race the world champion for 10km, Russia’s Vladimir Dyatchin became the first Olympian to be disqualified from the event for pushing things too far! Maybe the IOC should employ Vladimir to swim in the same lane as Michael Phelps at the 2012 games. A few grabs to the leg and kicks to the face should give Phelps’ rivals a chance at gold. That’s if Vladimir’s quick enough to get to him.

Davies, who finished sixth in the 1500m pool race a few days ago, set off at a remarkable pace as Maarten bided his time. Davies has not swum this distance very often so can be forgiven for losing his way in the final 500m. Maarten, a 25km endurance specialist, seized his chance and overtook. He acknowledged that the remarkable finishing time of 1:51:53.6hrs was 9500m down to Davies, 500m down to him. A very clever swim indeed.

I found it interesting to see the athletes provided with drinks for re-hydration, although at no point did I see an athlete consume one. Davies was exhausted by the end and placed on a stretcher before recovering so I wonder whether he drank anything other than the lake water and Vladimir’s sweat! Apparently the refreshments provided for the endurance events in Beijing have contained caffeine and sodium. Here’s a bit of research on both to discover whether this has helped or hindered the swimmers, runners and cyclists.

Sodium:

Athletes taking part in prolonged endurance exercise don’t need supplements to maintain normal levels of nutrition (i.e. sodium in the blood) and prevent the life-threatening sodium deficiency condition known as hyponatraemia. That’s the reassuring conclusion of a study of 413 triathletes who completed the 2001 Cape Town Ironman triathlon in South Africa. This study set out to test the prevailing wisdom that athletes need to ingest 20-40mmol per litre of sodium during exercise to preserve their normal blood sodium concentration and prevent hyponatraemia, particularly during ultradistance events, when total losses of sodium in sweat might be as high as 400-650mmol.

A total of 145 triathletes were randomly assigned to either an experimental or control group for the event, which comprised a 3.8k swim, 180k cycle ride and 42.2k run. Subjects in each group were given 40 tablets to take ad lib during the race, with a suggested range of one to four per hour. The tablets given to those in the experimental group contained 620mg of table salt while those given to the controls were filled with starch (placebo). Food and fluid intake – water or sports drink – were also allowed on an ad lib basis.

After the race, the researchers compared the blood sodium levels and various other parameters of these two groups and of the remaining 299 triathletes who had taken neither supplements nor placebo during the race.

Subjects in the sodium group consumed a mean of 14.7 tablets during the race, giving them an additional 156mmol of sodium. The placebo group took 15.8 of their dummy tablets. Nevertheless, there were no significant differences between the three groups in the following measures: finishing time; sodium concentration before and after the race; weight before and after the race; temperature and blood pressure after the race; perceived effort, muscle soreness and mental wellbeing. Only one athlete – in the placebo group – developed dangerous hyponatraemia during the race. He was the only athlete to show a substantial weight gain during the race and his problem was put down to drinking too much water.

‘We can reasonably conclude,’ say the researchers, ‘…that additional [sodium] supplementation is unnecessary during prolonged endurance exercise to maintain the serum [sodium] within the normal range.’ According to the scientists, this may be because athletes may sweat less or lose less sodium in their sweat than is currently believed, or that during states of acute sodium loss, additional sodium may be released from body stores to compensate for these losses until sodium supplies can be replenished at the next meal.

Caffeine:

Endurance athletes still take caffeine before their long-distance efforts, even though no study has ever linked the nerve-jangling chemical with heightened competitive performances over marathon-type distances.

True, caffeine can aid sprint performances, but that's no consolation for the multi-hour performer. In addition, caffeine has a troubling tendency to empty your body of water. Its diuretic effect can do more than increase the queues at Portaloos prior to races; pre-competition caffeine could also expel enough water to raise your body temperature and heart rate during exercise and increase your risk of dehydration.

However, if you want to take in some caffeine DURING your exertions, there's no problem, according to recent research at Ohio State University. At Ohio State, six athletes cycled for three hours at an intensity of 60% V02max (74 per cent of maximal heart rate) while ingesting a carbohydrate-electrolyte sports drink which on one occasion contained caffeine and on a separate date was caffeine-free. On two other days, the subjects tried the two beverages without engaging in any exercise at all.

When no exercise was carried out, caffeine acted as a strong diuretic, hiking urine production by a hefty 31 per cent. However, during the cycling trials, it was a different story altogether. As the cyclists pedaled along, the use of a caffeinated sports drink didn't boost urine output at all, compared to drinking a caffeine-free beverage. In addition, caffeine had no effect on heart rate, body temperature, perceived effort, or overall performance. This was in spite of the fact that the athletes were swallowing the equivalent of two cups of coffee per hour during their three-hour exertions.

What does this new information really mean for endurance athletes? Taking in 'de-fizzed,' caffeinated soda during exercise, as many athletes like to do, won't increase the risk of dehydration or harm performance, as many experts have suggested. In fact, if the soda is diluted a bit with water (adding one ounce of plain water for every two ounces of soda should be about right), it will make a pretty decent sports drink. In addition, the added caffeine might actually give an athlete a little more power during a full-tilt 'kick' at the end of a race.

So while it appears there is little harm in the added sodium and caffeine, it may not have helped Beijing’s endurance athletes all that much. Which just makes their achievements all the more impressive.

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