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May 26, 2025

The Hidden Risks of Overhydration in Endurance Athletes

Verified By
KIMS-SUNSHINE
Specialist,
26 May, 2025

The Hidden Risks of Overhydration in Endurance Athletes

Water is considered as the wellspring of life. Our body is made up of about 60% of water. Just as nourishing the body with nutritious food is important, so also hydrating the body with water is equally vital. However, overdoing it can prove dangerous at times and lead to life-threatening conditions, especially in endurance athletes. In this blog, we will look into the symptoms of overhydration and the reason why overhydration is harmful for endurance athletes.

Symptoms of overhydration in athletes

Water helps your body to regulate body temperature, prevent constipation, flush out harmful toxins, and perform all major bodily functions. However, over hydrating your body can lead to symptoms such as nausea and vomiting, headache due to pressure on the brain, drowsiness, muscle cramps, and changes in mental state like confusion and disorientation. Sometimes, electrolyte imbalance from overhydration can lead to a condition called hyponatremia.

What is hyponatremia in athletes?

Hyponatremia is a condition when the body experiences dangerously low concentrations of sodium in the blood due to excessive intake of water and other fluids, especially during or after extended periods of physical activity. This condition is more prominently seen in endurance athletes. Endurance athletes are those individuals who are engaged in sports or activities that require sustained physical effort over prolonged periods. Some of these sports or activities include long-distance running, cycling, swimming, or cross-country skiing. Those engaged in such sports sweat a lot and to replenish their body fluids, they end up drinking more water than is required. This is the most common hydration mistake endurance athletes make by over hydrating themselves with more water and fluids than is required.

Signs of drinking too much water during exercise

As stated above, drinking too much water can dilute the electrolyte concentration in the body, leading to tell-tale signs of excessive water intake during exercise. As a result, symptoms such as headache, muscle cramps, and even confusion can arise. It is true that the demand for water increases during or after exercise due to thirst and sweating, but it is important to understand how to avoid overhydration while running or engaging in some form of exercise or sport.

Dangers of over hydrating during long races

The most severe form of danger that arises due to overhydration during long races such as a marathon is hyponatremia. Hyponatremia occurs when the runner consumes so much fluid which does not get expelled out from the body in the form of urine or sweat. This leads to increased water levels and diluted sodium concentration in the bloodstream to abnormally low levels. In a bid to normalize sodium levels, the body cells undergo osmosis to draw water out of the blood and into the body cells. This causes the cells of the body to swell up. If this phenomenon transpires in the brain cells, it can pose a threat to the runner’s life. Thus, hyponatremia is by far, among the most potent risks of overhydration in endurance sports.

Now, the next thing that comes to mind is- how much water should runners drink? Runners should aim to replenish lost fluids by drinking approximately 235ml every 15-20 minutes. In general, the recommended daily intake of fluids for runners is about 2.7 liters for women and 3.7 liters for men. By keeping a tab on the water or fluid intake before, during, and after endurance sports can go a long way in preventing conditions such as hyponatremia.

Frequently Asked Questions

What is hyponatremia and how does it affect athletes?

Hyponatremia that occurs in individuals participating in endurance events like marathons, is called Exercise-Associated Hyponatremia (EAH). It typically occurs due to excessive fluid intake, sodium loss through sweat, and inefficient water excretion from the body. Owing to these factors there might be swelling in the athlete’s brain cells, which can lead to cerebral edema, a potentially life-threatening condition.

What are the signs of overhydration during exercise?

During exercise, there may be mild or severe signs of dehydration. Mild symptoms include nausea and vomiting, headache, muscle cramps or weakness, fatigue or drowsiness, and bloating or swelling of certain parts of the body like hands, feet, and stomach. The more severe signs include confusion or disorientation, seizures, and loss of consciousness or coma.

Can overhydration cause cramps or confusion?

Yes, overhydration can indeed cause cramps and confusion. This is because of a condition called hyponatremia where the brain swells up due to increased intracranial pressure on the cells which can manifest as confusion and disorientation or cramps.

How do I balance electrolytes while running?

The most common electrolytes found in the body include sodium, potassium, magnesium, and calcium. They help in regulating fluid balance and hence, it is vital to replenish electrolytes lost through sweat, especially in hot and humid conditions. For this purpose, it is important to consume the right fluids for electrolyte uptake by the body. Having coconut water which is naturally rich in electrolytes, is one such way to balance electrolytes in the body.

Should I use sports drinks instead of plain water?

Generally, for short-duration and low-intensity exercises, plain water is sufficient to keep yourself hydrated. However, if you are engaging in prolonged and high-intensity exercise like running in marathons, sports drinks may be more beneficial.

Is thirst a reliable indicator for hydration in athletes?

Thirst is a natural way of the body to indicate the need for fluids. However, relying solely on thirst as a sign for hydration in athletes may not always be sufficient.