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09.07.2009

Hyperhydration helps endurance athletes

If you drink more fluid than you need at that moment just before starting a lengthy cardio or running session, your performance will improve, discovered researchers at the University of Sherbrooke in Canada. Hyperhydration, a long word for taking in liquid when you're not thirsty, is performance enhancing for endurance athletes.

If you lose two percent of your bodyweight through transpiration, your performance declines. Since that has been known, sports scientists have directed much of their research to learning about the effects of hyperhydration. But, according to the Canadians, the results of this research have been difficult to translate into practice. The studies were mainly done on athletes who had been deliberately dehydrated first. In real life athletes don't do this. That makes the Canadian study interesting, because it compares the effects of normal fluid provision – euhydration – with the effects of hyperhydration.

In their study, which was published in 2008 in the Journal of Physiological Anthropology, the Canadians did an experiment with six trained athletes. In one session the athletes cycled without special preparation for two hours at 65 percent of their VO2max. During the two hour period the athletes had to do five bursts at 80 percent of their VO2max. At the end of the two hours they did an exhaustion trial, increasing their speed until they could go no further.

In the other session the athletes drank 1.7 litres of water before and during the trial. The water contained 82 g of glycerol. Glycerol is a component of fat – think of it as the little sphere that three fatty acids are attached to. Glycerol is also found in a free form in the human body. If you drink a lot of water, glycerol reduces the rate at which your kidneys pass the extra fluid to your bladder.

The hyperhydration worked. The body temperature of the hyperhydration group was lower, but the effect was not significant. What was significant was the effect on the heart. The hyperhydration group had a lower heart rate. In the graph below the curve with the squares represents this group.

The hyperhydrated cyclists also managed to cycle for longer in the exhaustion trial [see below]. PEH = hyperhydration group. The hyperhydrated athletes kept on cycling for fourteen minutes; the euhydrated cyclists only managed twelve minutes. The peak capacity in the hyperhydration group was also higher in the exhaustion trial: 280 Watt. In the euhydration group the figure was 266 Watt.

On a side note, hyperhydration doesn't have the same effect in everybody. "One subject had a decrease in endurance capacity with preexercise hyperhydration", write the Canadians.

Source:
J Physiol Anthropol. 2008 Sep;27(5):263-71.

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