Hydration plays a vital role in both athletic performance and long-term health, yet research shows that many people misunderstand how much—and what—they should drink. Evidence suggests that both over-hydration and under-hydration can pose serious risks, while the type of fluid consumed may also influence outcomes such as muscle cramping.
A study conducted by researchers at Loyola University Health System found that nearly half of recreational runners may be drinking too much fluid during races. Although expert guidelines recommend drinking only when thirsty, the survey revealed that 36.5% of runners drink according to a preset schedule or to maintain a certain body weight, and 8.9% drink as much as possible. Additionally, 29.6% of runners incorrectly believe they need to ingest extra salt while running, and 57.6% report consuming sports drinks because they think electrolytes prevent low blood sodium.
In reality, the main cause of low sodium in runners is excessive fluid intake. Drinking too much—whether water or sports drinks—can lead to exercise-associated hyponatremia, a potentially fatal condition in which the sodium content of the blood becomes dangerously diluted. This often occurs when runners drink even when they are not thirsty. Symptoms of hyponatremia include nausea, vomiting, headache, confusion, loss of energy, muscle weakness, spasms, or cramps. In severe cases, it can result in seizures, unconsciousness, and coma. In recent years, there have been 12 documented and 8 suspected deaths among runners linked to this condition.
Experts emphasize that drinking according to thirst is the safest approach. The International Marathon Medical Directors Association supports this guideline, noting that it helps prevent over-consumption of fluids. Researchers also point out that the body naturally loses some fluid during exercise, and runners should expect to lose several pounds without concern. Misconceptions about hydration may partly stem from sports drink advertising in the 1980s and 1990s, which warned heavily about dehydration and encouraged high fluid intake—sometimes as much as 1.2 litres per hour. Although such messaging has changed, these beliefs persist among many athletes.
While over-hydration during exercise is a concern, insufficient hydration over the long term may also have serious consequences. Research presented at ESC Congress 2021 suggests that staying well-hydrated throughout life could reduce the risk of developing heart failure. The study, led by Natalia Dmitrieva from the National Heart, Lung, and Blood Institute, found that higher serum sodium levels—a reliable indicator of lower fluid intake—were associated with increased risks of heart failure and thickening of the heart’s main pumping chamber, known as left ventricular hypertrophy.
The long-term analysis followed 15,792 adults aged 44 to 66 over a period of 25 years as part of the Atherosclerosis Risk in Communities (ARIC) study. Participants were grouped according to their average serum sodium levels in midlife. Results showed that higher sodium concentrations were linked to greater likelihood of developing both heart failure and left ventricular hypertrophy later in life, even after accounting for factors such as age, blood pressure, kidney function, cholesterol, blood glucose, body mass index, sex, and smoking status. Each 1 mmol/l increase in serum sodium was associated with a 20% higher risk of left ventricular hypertrophy and an 11% higher risk of heart failure. Notably, risks began to rise when sodium levels exceeded 142 mmol/l, a range still considered normal in standard lab tests.
These findings suggest that consistent hydration habits over time are important for cardiovascular health. When fluid intake is too low, the body activates mechanisms to conserve water, which may contribute to structural and functional changes in the heart. General recommendations suggest daily fluid intake of approximately 1.6 to 2.1 litres for women and 2 to 3 litres for men, although many people do not meet even the lower end of these guidelines.
Adding another dimension to hydration science, research from Edith Cowan University highlights that the type of fluid consumed can significantly affect muscle function. The study, published in the Journal of the International Society of Sports Nutrition, found that drinking electrolyte-enhanced fluids during and after exercise can reduce susceptibility to muscle cramps compared to drinking plain water.
Muscle cramps are a common and painful condition, affecting approximately 39% of marathon runners, 52% of rugby players, and 60% of cyclists. Lead researcher Ken Nosaka explained that while many people attribute cramps to dehydration, the evidence suggests that a lack of electrolytes plays a more significant role. Drinking only water may actually increase the risk of cramps because it dilutes the body's electrolyte concentration without replacing those lost through sweat.
In the study, participants exercised in hot conditions and were tested under two scenarios: consuming plain water and consuming an electrolyte solution. Researchers found that muscles became more prone to cramping when participants drank only water, whereas consuming electrolytes increased resistance to cramping. Electrolytes—including sodium, potassium, magnesium, and chloride—are essential for muscle function and help the body absorb fluids more effectively. Electrolyte-containing solutions, such as oral re-hydration drinks, can be especially beneficial during exercise, in hot environments, or during illness involving fluid loss, such as diarrhoea or vomiting. These findings suggest that hydration strategies should consider not only the amount but also the composition of fluids consumed. Sona Electrolytes Effervescent Tablets provide this specific mineral support, offering a measured blend of sodium, potassium, chloride and magnesium. The effervescent format ensures that fluid intake is consistently backed by the essential minerals required for muscle function and effective hydration throughout the day
Overall, the combined research underscores a nuanced message: effective hydration is about balance. Drinking too much fluid during exercise can be dangerous, while chronic under hydration may increase long-term health risks such as heart failure. At the same time, replacing lost electrolytes is crucial for preventing muscle cramps and maintaining proper bodily function. The most effective approach is to align fluid intake with the body’s natural signals, maintain consistent hydration habits, and choose appropriate fluids based on activity level and conditions.
References;
Loyola University Health System: Research on runner hydration and Exercise-Associated Hyponatremia (EAH).Access from: https://pubmed.ncbi.nlm.nih.gov/20876587/
European Society of Cardiology (2021): Long-term hydration habits and cardiovascular health outcomes (ARIC Study).