Electrolytes Explained: More Than Just Sports Drinks
Electrolytes are often marketed as a simple ingredient in a brightly coloured sports drink, but their physiological importance extends far beyond that. Electrolytes play fundamental roles in maintaining fluid balance, supporting neuromuscular functions and energy metabolism. During high-intensity exercise, your body loses water through sweat, which is the body’s main homeostatic mechanism to maintain optimal body temperature. Electrolytes are essential to this thermoregulatory process, facilitating fluid movement through the sweat glands, and as a result, they are lost from the body along with water. Their excessive loss, however, can lead to dehydration, reduced exercise performance during training and suboptimal recovery if they are not replenished.
In this article, we’ll break down the science of electrolytes and explain why they are an indispensable strategy to maintaining exercise performance.
What Are Electrolytes in the Body?
Electrolytes are essential minerals that carry an electric charge when dissolved in bodily fluids such as blood, plasma, and intracellular and extracellular fluids. The most common examples include sodium, potassium, calcium and magnesium. These charged ions are crucial for many physiological processes, including the maintenance of proper hydration and blood volume by regulating the movement of water between cells. Electrolytes also play a role in neuromuscular function by regulating electrical impulses in the nerves and muscles, enabling muscle contractions.
Examples of Electrolytes & Their Functions
- Sodium= It is the most abundant electrolyte in the extracellular fluid, where it controls the movement of fluid across cells, supporting adequate hydration, blood pressure and blood volume. It also plays a central role in nerve impulse transmission, supporting muscle contractions (Veniamakis et al., 2022a).
- Potassium= This mineral is the most abundant electrolyte in the intracellular fluid, where it works with sodium in supporting neuronal transmission and muscle contraction (Ghazzawi et al., 2023).
- Calcium= Calcium plays a central role in muscle function by supporting adequate contraction of muscle fibres, ensuring muscle strength and power. Alongside potassium and sodium, it also supports neurotransmission (Ghazzawi et al., 2023).
- Magnesium= Magnesium is required for ATP production, making it essential for energy metabolism during exercise. It also regulates calcium levels within the muscle, helping maintain efficient muscle contractions and relaxation (Ghazzawi et al., 2023).
How Electrolytes Are Lost During Exercise
Your body relies on a continuous energy supply during exercise, which is ensured by oxidation of various fuel sources such as carbohydrates or fats. This process supports muscle contraction, which generates a lot of heat in the body and increases the body’s temperature (Keefe et al., 2024). In order to maintain the body’s temperature, increase blood delivery to the skin, and sweating occurs. Sweat evaporation, in turn, dissipates heat during exercise, which cools your body down (Keefe et al., 2024).
Electrolytes play an essential role in this process as they create an osmotic gradient, allowing the water to move across the skin, which is how electrolytes are lost during exercise (Keefe et al., 2024).
The primary mineral lost through sweat is sodium, followed by potassium, magnesium and calcium. The rate of sweat production, and so electrolyte loss, isn’t uniform in every individual and depends on many factors:
- Exercise duration & intensity= With higher exercise intensity as well as longer duration, more heat is produced due to higher energy demands. This results in higher water and electrolyte losses (Baker et al., 2019).
- Humidity & hot environmental conditions= Higher ambient temperature naturally increases the body’s temperature and sweat production, so exercising in hot environments will increase electrolyte loss. Humidity, on the other hand, decreases sweat evaporation, increasing overall sweat production to compensate for it (Baker, 2017).
- Individual physiology= Some individuals naturally lose more electrolytes, particularly sodium, through sweat, which can be influenced by genetics, body size and training status (Baker, 2017).
Why Are Electrolytes Important for Athletes?
Electrolytes are critical for sustaining exercise performance, particularly during prolonged or high-intensity training. Excessive electrolyte loss negatively affects performance, especially sodium loss due to its high concentration in sweat (Baker et al., 2019). Sodium supports fluid balance and blood volume, helping maintain oxygen delivery to working muscles and the removal of metabolic by-products such as lactate during exercise. This helps reduce muscle fatigue and improve muscle endurance (Choi et al., 2021).
Potassium, calcium and magnesium further support sustained muscle contraction and relaxation, enabling endurance and power output during training (Veniamakis et al., 2022b). Maintaining electrolyte balance before and during exercise helps athletes preserve performance capacity and delay fatigue.
What Happens When Your Body is Low on Electrolytes?
When electrolytes are not adequately replenished, their loss can lead to dehydration, muscle cramps, increased muscle fatigue and reduced endurance (Choi et al., 2021). Low sodium levels impair cardiovascular performance and accelerate the onset of fatigue, while inadequate potassium, calcium and magnesium compromise normal muscle contraction and relaxation (Choi et al., 2021; Naderi et al., 2025). Additionally, dehydration can considerably impact cognitive performance during exercise, leading to impaired attention, slower reaction time and impaired decision making (The American College of Sports Medicine, 2007)
These effects collectively reduce exercise capacity and increase the risk of early fatigue, especially during long or intense training sessions.
Why Electrolytes Matter for Women
Women are particularly susceptible to electrolyte loss during exercise and the associated negative consequences, which are influenced by hormonal fluctuations during the menstrual cycle and lower total body water. Estrogen plays a key role in electrolyte balance by promoting sodium and water retention, while progesterone has the opposite effect (Sims et al., 2023). As estrogen levels decline during the late luteal phase and menstruation, the risk of electrolyte losses increases.
Additionally, because females generally have lower total body water than males, the same absolute loss of water and electrolytes represents a larger proportion of their body fluid (Sims et al., 2023). This means that even moderate sweating can lead to a faster reduction in plasma volume, impair thermoregulation, and increase the risk of dehydration, fatigue, and reduced exercise performance (Sims et al., 2023; Convit et al., 2025).
When to Take Electrolytes
Knowing when to take electrolytes is just as important as understanding their function. Electrolyte needs vary depending on training intensity, duration, environmental conditions and individual sweat rates.
Before Exercise
Electrolytes taken before training help maintain hydration status and blood volume during exercise, particularly when exercising in hot or humid conditions or when it is necessary to correct inadequate fluid and electrolyte intake. Adequate sodium intake before exercise prevents dehydration and prepares the body for sweat-related losses (The American College of Sports Medicine, 2007).
During Exercise
During prolonged or high-intensity exercise, electrolyte intake helps replace minerals lost through sweat and supports sustained exercise performance. This is particularly important for endurance training, training sessions lasting longer than 60 minutes, or sessions performed in high temperatures, as these factors increase overall electrolyte losses (The American College of Sports Medicine, 2007).
After Exercise
After training, electrolytes support rehydration and recovery by restoring fluid balance and correcting electrolyte deficits. Post-exercise electrolyte intake through electrolyte drinks or meals with sodium helps normalise plasma volume, reduce dehydration and prepare the body for subsequent training sessions (The Amercian College of Sports Medicine, 2007).
Electrolytes should therefore be consumed before, during or after exercise, depending on individual needs, sweat losses and training demands.
Conclusion
Electrolytes are far more than a minor ingredient in sports drinks. They are lost through sweat during exercise and play essential roles in hydration, muscle function and performance. Athletes training in hot environments, those exercising for long durations, and individuals who naturally lose more electrolytes should pay particular attention to adequate electrolyte intake before, during and after exercise to support performance and recovery.
References:
Baker, L.B. (2017) ‘Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability’, Sports Medicine (Auckland, N.z.), 47(Suppl 1), pp. 111–128. Available at: https://doi.org/10.1007/s40279-017-0691-5.
Baker, L.B. et al. (2019) ‘Exercise intensity effects on total sweat electrolyte losses and regional vs. whole-body sweat [Na+], [Cl−], and [K+]’, European Journal of Applied Physiology, 119(2), pp. 361–375. Available at: https://doi.org/10.1007/s00421-018-4048-z.
Choi, D.-H. et al. (2021) ‘Effects of Electrolyte Supplements on Body Water Homeostasis and Exercise Performance during Exhaustive Exercise’, Applied Sciences, 11(19), p. 9093. Available at: https://doi.org/10.3390/app11199093.
Convit, L. et al. (2025) ‘Sodium Hyperhydration Improves Performance With No Change in Thermal and Cardiovascular Strain in Female Cyclists Exercising in the Heat Across the Menstrual Cycle’, International Journal of Sport Nutrition and Exercise Metabolism, 35(2), pp. 99–111. Available at: https://doi.org/10.1123/ijsnem.2024-0125.
Ghazzawi, H.A. et al. (2023) ‘Exploring the Relationship between Micronutrients and Athletic Performance: A Comprehensive Scientific Systematic Review of the Literature in Sports Medicine’, Sports, 11(6), p. 109. Available at: https://doi.org/10.3390/sports11060109.
Keefe, M.S. et al. (2024) ‘Importance of Electrolytes in Exercise Performance and Assessment Methodology After Heat Training: A Narrative Review’, Applied Sciences, 14(22), p. 10103. Available at: https://doi.org/10.3390/app142210103.
Naderi, A. et al. (2025) ‘Nutritional Strategies to Improve Post-exercise Recovery and Subsequent Exercise Performance: A Narrative Review’, Sports Medicine (Auckland, N.z.), 55(7), pp. 1559–1577. Available at: https://doi.org/10.1007/s40279-025-02213-6.
Sims, S.T. et al. (2023) ‘International society of sports nutrition position stand: nutritional concerns of the female athlete’, Journal of the International Society of Sports Nutrition, 20(1), p. 2204066. Available at: https://doi.org/10.1080/15502783.2023.2204066.
The American College of Sports Medicine (2007) ‘Exercise and Fluid Replacement’. Available at: https://journals.lww.com/acsm-msse/fulltext/2007/02000/exercise_and_fluid_replacement.22.aspx (Accessed: 30 December 2025).
Veniamakis, E. et al. (2022a) ‘Effects of Sodium Intake on Health and Performance in Endurance and Ultra-Endurance Sports’, International Journal of Environmental Research and Public Health, 19(6), p. 3651. Available at: https://doi.org/10.3390/ijerph19063651.
Veniamakis, E. et al. (2022b) ‘Effects of Sodium Intake on Health and Performance in Endurance and Ultra-Endurance Sports’, International Journal of Environmental Research and Public Health, 19(6), p. 3651. Available at: https://doi.org/10.3390/ijerph19063651.
