Whether you run in the park in the morning or participate in endurance competitions, proper hydration means more than simply drinking water. Electrolytes, although often overlooked, play an essential role in physical performance, recovery, muscle function, and overall health. Maintaining a good balance between fluids and electrolytes is important for athletes at all levels of training.

Water represents approximately 50–70% of body weight and supports almost all physiological functions in the body, including temperature regulation, nutrient transport, waste elimination, and joint lubrication (Amawi et al., 2024). During exercise, however, sweating causes not only water loss but also the loss of important electrolytes such as sodium, chloride, potassium, magnesium, and calcium.

Sodium and chloride help regulate fluid balance and osmotic pressure, while potassium contributes to normal muscle and heart function. Magnesium and calcium are involved in muscle contraction and nerve signaling. Research shows that losing only 2% of body weight through sweating may negatively affect endurance, coordination, concentration, and athletic performance, especially during prolonged exercise (McCartney et al., 2017).

Several factors can influence fluid and electrolyte balance during physical activity. Individual sweat rate is one of the most important, as some athletes lose significantly more sodium through sweat than others and may therefore require higher electrolyte intake (Baker et al., 2016). Environmental conditions also play an important role. High temperatures and humidity increase sweating, while cold environments and altitude may increase fluid losses through respiration.

Training level may also influence hydration needs. Well-trained athletes often sweat more efficiently to regulate body temperature, but they may simultaneously lose larger amounts of electrolytes during prolonged exercise.

Dehydration occurs when fluid losses are not adequately replaced. Common symptoms include strong thirst, fatigue, muscle cramps, dizziness, headaches, and dark-colored urine. Severe dehydration may impair physical and cognitive performance and, in extreme cases, may affect internal organ function (Maughan, 2012).

At the same time, excessive water intake without adequate sodium replacement may lead to exercise-associated hyponatremia, a potentially dangerous condition characterized by low sodium concentration in the blood (Hew-Butler et al., 2017). Symptoms may include nausea, headaches, confusion, and, in severe situations, seizures or coma. This condition is more commonly reported in endurance athletes who consume large quantities of water without electrolyte replacement.

Practical hydration strategies should begin before exercise. General recommendations suggest consuming approximately 400–600 ml of water or an electrolyte beverage 2–3 hours before exercise, followed by another 150–250 ml about 30–60 minutes before activity, especially in hot conditions (Belval et al., 2019).

During exercise, athletes are generally advised to drink approximately 150–300 ml of fluids every 15–20 minutes. For activities lasting longer than one hour, beverages containing sodium and carbohydrates may help maintain hydration and energy availability. Sports drinks commonly contain around 300–700 mg sodium per liter together with small amounts of carbohydrates such as glucose or maltodextrin (Sawka et al., 2007).

After exercise, rehydration remains essential for recovery. Specialists often recommend replacing approximately 125–150% of the body mass lost through sweating. In practical terms, losing 1 kg during exercise usually corresponds to replacing around 1.25–1.5 liters of fluids gradually over the following hours (Shirreffs et al., 1996). Sodium intake after exercise may also improve fluid retention and reduce excessive urine production (Ray et al., 1998).

Athletes can estimate their own sweat losses relatively easily by measuring body weight before and after exercise sessions under similar conditions. This simple method may help individualize hydration strategies and improve both safety and performance.

In conclusion, maintaining a proper balance between fluids and electrolytes is not only a health recommendation but also an important performance strategy. Hydration needs vary between individuals depending on sweat rate, exercise intensity, environmental conditions, and training status. Understanding these individual differences and adapting hydration plans accordingly may help athletes improve performance, recovery, and overall safety during exercise.

References

Amawi, A., AlKasasbeh, W., Jaradat, M., Almasri, A., Alobaidi, S., Abu Hammad, A., Bishtawi, T., Fataftah, B., Turk, N., Al Saoud, H., Jarrar, A., & Ghazzawi, H. (2024). Athletes’ nutritional demands: a narrative review of nutritional requirements. Frontiers in Nutrition, 10, 1331854.

Baker, L. B., Barnes, K. A., Anderson, M. L., Passe, D. H., & Stofan, J. R. (2016). Normative data for regional sweat sodium concentration and whole-body sweating rate in athletes. Journal of Sports Sciences, 34(4), 358–368.

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.

Hew-Butler, T., Loi, V., Pani, A., & Rosner, M. H. (2017). Exercise-associated hyponatremia: 2017 update. Frontiers in Medicine, 4, 21.

Maughan, R. J. (2012). Investigating the associations between hydration and exercise performance: methodology and limitations. Nutrition Reviews, 70(Suppl. 2), S128–S131.

McCartney, D., Desbrow, B., & Irwin, C. (2017). The effect of fluid intake following dehydration on subsequent athletic and cognitive performance: a systematic review and meta-analysis. Sports Medicine – Open, 3(1), 13.

Ray, M. L., Bryan, M. W., Ruden, T. M., Baier, S. M., Sharp, R. L., & King, D. S. (1998). Effect of sodium in a rehydration beverage when consumed as a fluid or meal. Journal of Applied Physiology, 85(4), 1329–1336.

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.

Shirreffs, S. M., Taylor, A. J., Leiper, J. B., & Maughan, R. J. (1996). Post-exercise rehydration in man: effects of volume consumed and drink sodium content. Medicine & Science in Sports & Exercise, 28(10), 1260–1271.