The Negative Effects of Overhydration

There is no question that hydration is essential for optimum running. A runner stands no chance of performing well in workouts or races without proper fluid intake. However, many runners do not understand that overhydration, also known as hyponatremia, can be just as damaging to a runner’s performance as dehydration. Overhydration can result in low blood sodium levels that can cause muscle soreness, nausea, and even death. has a great post from running coach Jeff Gaudette about some of the misconceptions concerning hydration.

The only symptom of dehydration is thirst and often, this thirst becomes so overwhelming that the athlete is compelled to drink when fluid is available.

Furthermore, studies have disproved the claim that a reduction in body weight of less than 2 percent results in impaired performance. For example, a recent study confirmed that Haile Gebrselassie lost 10 percent of his body mass due to dehydration during his world record marathon run in Berlin.

The results of this latest research show, for the first time, that drinking according to thirst is the superior hydration protocol to maximize performance.

The key takeaway is that runners should drink fluids to their level of thirst. If you are not thirsty, there is no reason to pound water and sports drinks. Runners who drink too much fluid before a race sabatoge their performances even though they have good intentions.

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