Whether you are a professional athlete or simply enjoy being physically active, proper hydration is essential for both heart health and athletic performance. Although hydration may seem like a simple topic, its real importance is often underestimated, and the consequences of dehydration can sometimes be serious.

Why Is Hydration Important in Sports?

During physical exercise, body temperature increases and the body removes excess heat mainly through sweating. This process leads to the loss of fluids and electrolytes, which can affect several important body functions, including heart activity, body temperature regulation, muscle function, oxygen transport, and recovery after exercise (Maughan & Meyer, 2013).

Research shows that losing more than 2% of body weight through sweating may significantly reduce endurance, concentration, and physical performance, while also increasing the risk of heat-related problems and injuries (Goulet, 2012; Sawka et al., 2007).

What Happens When You Become Dehydrated?

The effects of dehydration may appear even before a person feels thirsty. Many athletes incorrectly believe that thirst is the best indicator of dehydration, but studies suggest that the body may already be in a dehydrated state before thirst becomes noticeable (Belval et al., 2019).

Common symptoms of dehydration include:

  • Increased body temperature
  • Fatigue
  • Difficulty concentrating
  • Muscle cramps
  • Increased heart rate
  • Slower recovery after exercise

Hydration Strategies for Athletes

Before Exercise

It is important to begin exercise already well hydrated. General recommendations suggest:

  • Drinking approximately 500–600 ml of water 2–3 hours before exercise
  • Drinking another 250–300 ml about 20–30 minutes before training or competition

Morning workouts require special attention because the body may already be mildly dehydrated after sleep. Drinking a glass of water immediately after waking up may help restore fluid balance.

People who sweat heavily or are more prone to dehydration may also benefit from electrolyte intake, including sodium, potassium, and magnesium, which help maintain fluid balance in the body (Königstein et al., 2020).

During Exercise

Hydration needs during exercise depend on factors such as exercise duration, intensity, temperature, and humidity. General recommendations suggest drinking approximately 150–250 ml of fluids every 15–20 minutes during physical activity (Belval et al., 2019).

In hot or humid conditions, beverages containing electrolytes may help replace minerals lost through sweating and support hydration more effectively.

In endurance sports, athletes often estimate sweat losses by comparing body weight before and after exercise:

  • Body weight before exercise – body weight after exercise = fluid loss

A loss of 1 kg usually corresponds to approximately 1 liter of fluid lost through sweating. Specialists generally recommend replacing around 50–70% of these losses during exercise, as full replacement is neither necessary nor without risk (Sawka et al., 2007; Belval et al., 2019).

After Exercise

Recovery after exercise also includes restoring fluid balance. If an athlete loses approximately 1 kg through sweating, it is generally recommended to consume around 1.5 liters of fluids gradually during the following hours (Belval et al., 2019).

Post-exercise hydration may include:

  • Water for light or moderate exercise
  • Electrolyte drinks after prolonged or intense activity
  • Salty snacks, such as nuts or whole-grain crackers, to help restore sodium levels

Hydration and Heart Health

Proper hydration helps the cardiovascular system function efficiently. When the body becomes dehydrated, blood volume decreases and the blood becomes more concentrated. As a result, the heart has to work harder to circulate blood and deliver oxygen to muscles and organs.

These effects become even more significant during intense physical activity or in hot environmental conditions, when the cardiovascular system is already under additional stress.

Common Hydration Mistakes

Several common mistakes may negatively affect hydration and performance:

  • Ignoring hydration before exercise
  • Choosing beverages with excessive sugar
  • Drinking large amounts of water without electrolyte replacement
  • Excessive consumption of energy drinks or highly caffeinated beverages

Excessive water intake without sufficient sodium replacement may contribute to exercise-associated hyponatremia, a potentially dangerous condition characterized by low sodium levels in the blood (Hew-Butler et al., 2015; Almond et al., 2005).

Conclusion

Proper hydration means more than simply drinking water when feeling thirsty. It involves planning fluid intake according to exercise intensity, environmental conditions, and individual needs.

Maintaining adequate hydration can protect cardiovascular health, support both physical and mental performance, and improve recovery after exercise. For this reason, hydration should be considered an essential part of every training program.

References

Almond, C. S. D., Shin, A. Y., Fortescue, E. B., Mannix, R. C., Wypij, D., Binstadt, B. A., Duncan, C. N., Olson, D. P., Salerno, A. E., Newburger, J. W., & Greenes, D. S. (2005). Hyponatremia among runners in the Boston Marathon. New England Journal of Medicine, 352(15), 1550–1556.

Belval, L. N., Hosokawa, Y., Casa, D. J., Adams, W. M., Armstrong, L. E., Baker, L. B., Burke, L., Cheuvront, S., Chiampas, G., González-Alonso, J., Huggins, R. A., Kavouras, S. A., Lee, E. C., McDermott, B. P., Miller, K., Schlader, Z., Sims, S., Stearns, R. L., Troyanos, C., & Wingo, J. (2019). Practical hydration solutions for sports. Nutrients, 11(7), 1550.

Goulet, E. D. B. (2012). Dehydration and endurance performance in competitive athletes. Nutrition Reviews, 70(Suppl. 2), S132–S136.

Hew-Butler, T., Rosner, M. H., Fowkes-Godek, S., Dugas, J. P., Hoffman, M. D., Lewis, D. P., Maughan, R. J., Miller, K. C., Montain, S. J., Rehrer, N. J., Roberts, W. O., Rogers, I. R., Siegel, A. J., Stuempfle, K. J., Winger, J. M., & Verbalis, J. G. (2015). Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015. Clinical Journal of Sport Medicine, 25(4), 303–320.

Königstein, K., Niess, A. M., Carlsohn, A., & Treff, G. (2020). Hydration management in sports. Deutsche Zeitschrift für Sportmedizin, 71(1), 5–12.

Maughan, R. J., & Meyer, N. L. (2013). Hydration during intense exercise training. Nestlé Nutrition Institute Workshop Series, 76, 25–37.

Sawka, M. N., Burke, L. M., Eichner, E. R., Maughan, R. J., Montain, S. J., & Stachenfeld, N. S. (2007). American College of Sports Medicine position stand: Exercise and fluid replacement. Medicine & Science in Sports & Exercise, 39(2), 377–390.