When we think of performance, we often focus on protein and carbs. While critical, electrolytes also play a major role in performance. Minerals such as sodium, chloride, potassium, andmmagnesium are amongst the most crucial electrolytes, as they control how our muscles contract, how our nerves send signals, and how our body remains hydrated.
During training or competition, especially in heat or long sessions, you lose electrolytes through sweat. If you don’t replace them properly, your body can struggle to regulate temperature, your muscles can cramp, and your performance drops.
This article looks at the four main electrolytes, and their role around workout and training.
Sodium (Na+): The Key to Staying Hydrated and Performing Longer
Sodium is the most important electrolyte when it comes to hydration and performance. It helps your body hold onto water, maintains blood volume, and keeps your nerves and muscles firing properly. When sodium levels drop too low (a condition called hyponatremia), athletes often experience fatigue, dizziness, cramps, or nausea, especially in long races or hard training in heat.
In a study conducted by Savoie FA et al., 2016, Journal of Strength and Conditioning Research. They provided sixteen healthy men with three separate pre-hydration protocols before exercise. In one condition, they took sodium chloride (salt) tablets plus fluid. In another, the same amount of salt was dissolved directly into the fluid. In the third, they used glycerol (a different hyperhydration method). The sodium chloride dose in the salt-solution condition was very high — roughly 7.5 grams of salt per liter, which is about 2,900+ mg sodium per liter — while this amount is well above normal sports drink ranges, it was used to intentionally “super-load” sodium and increase total body water before exercise. They then measured urine output, fluid retention, and blood volume changes over several hours.
What they found is that the sodium-in-water strategy (salt dissolved in the drink) led to the highest fluid retention and the lowest urine output, meaning the body held onto more of what it drank. Both sodium strategies (tablets or dissolved) worked better than glycerol for keeping more fluid in the body before exertion. Importantly, none of the sodium strategies caused major negative symptoms.
Why it matters:
“Preloading” sodium before long or hot training can increase how much fluid your body is going to hold on to, which helps delay dehydration, reduce cardiovascular strain, and maintain pace longer — especially in events where you know you’ll sweat heavily.
In another study conducted by Wijering LAJ et al. (2022), at the European Journal of Applied Physiology, researchers tested cyclists who trained in the heat while drinking beverages containing different sodium concentrations — low (230 mg/L) vs. high (690 mg/L). The high-sodium group maintained plasma sodium concentration and blood volume, while the low-sodium group showed signs of early dehydration and reduced cardiovascular stability.
In other words, Sodium-rich fluids (around 500–700 mg per liter) are more effective for maintaining hydration, supporting endurance, and preventing performance drops in hot environments.
Practical Guidance:
Before exercise: 400–600 mg sodium (1⁄4 tsp of salt) about an hour before training.
During: 500–700 mg sodium per liter of water for workouts >60 minutes.
After: Rehydrate with 1–1.5 L of fluid per kilogram of body weight lost, containing at least 500 mg sodium per liter.
Chloride (Cl−): Sodium’s Hydration Partner
Chloride works side by side with sodium. They’re almost always found together as sodium chloride (table salt). Chloride helps maintain fluid balance between cells, supports blood pressure regulation, and assists in the formation of stomach acid, which helps digestion and nutrient absorption.
Most rehydration studies use NaCl (table salt) as their sodium source, so athletes naturally replace chloride when consuming sodium-containing drinks. For instance, in a study by Shirreffs et al. (2003), both sodium and chloride were replaced using regular salt, which effectively restored hydration and electrolyte balance after exercise.
For athletes, focus on replacing sodium through regular salt or sports drinks made with sodium. As long as your sodium intake is adequate, chloride will be restored automatically — no separate supplement is needed.
Potassium (K+): Rehydrating Inside the Muscle Cell
Potassium is the main electrolyte inside your muscle cells. It works with sodium to control muscle contractions, nerve function, and the balance of fluids between cells. During exercise, especially in long or repeated sessions, potassium levels drop inside muscle cells, which can affect muscle force and endurance.
A 1995 study by Lindinger on potassium regulation during exercise, explains how potassium levels change in the blood and muscles during and after exercise and how those changes affect muscle fatigue and heart function. According to the study, at the start of exercise, contracting muscles release potassium, which raises its levels in the blood and lowers potassium inside muscle cells. These shifts can contribute to fatigue because they disrupt normal muscle electrical activity. The amount of potassium released depends on exercise intensity, training level, and factors like beta-blockers or caffeine. Other tissues in the body help remove the potassium from the blood during exercise to prevent dangerously high levels that could impair muscle or heart function. After exercise stops, blood potassium levels drop quickly — sometimes below normal — which can last for a while and may affect heart rhythm. The paper also notes that increased catecholamines (like adrenaline) during exercise appear to protect the heart from the potentially harmful effects of these potassium changes.
Another study by Cairns (2023), conducted on isolated mouse muscle fibers, showed that when glycogen levels are low and potassium balance is disrupted, the ability of muscle fibers to generate force drops significantly. While performed in mice, the findings are cellular-level, meaning the same mechanisms likely apply to human muscle fatigue during intense or prolonged exercise.
For most people, potassium intake from food (bananas, oranges, avocados, sweet potatoes) is enough. But for workouts lasting longer than 90 minutes, aim for 150–250 mg of potassium per liter of fluid in your sports drink. After training, include potassium-rich foods or recovery drinks with about 300–500 mg to help replenish muscle energy stores and prevent cramping.
Magnesium (Mg2+): Energy, Recovery, and Muscle
Relaxation Magnesium is often called the “muscle recovery mineral.” It’s needed for more than 300 processes in the body, including energy production (ATP), muscle relaxation, and nerve signal transmission. While sweat losses are smaller than sodium or potassium, many athletes don’t get enough magnesium in their diet — especially those who eat fewer whole grains, nuts, or greens.
From a research standpoint, While the direct impact of magnesium on athletic performance is mixed, its role in recovery and fatigue management shows promise. For instance, a study by V. Cinar (2006) demonstrated that active subjects taking 10mg of magnesium per kilogram of body weight daily for four weeks experienced a significant decrease in plasma lactate levels at exhaustion. Lactate reduction is known to contribute to reduced muscle fatigue and faster recovery. This suggests that magnesium supplementation could positively affect athletic performance by reducing this key metabolic stressor.
Conclusion
Electrolytes are the silent drivers of performance. They keep your muscles contracting, your nerves firing, and your fluids balanced. Aiding in improved energy output, improved endurance and even faster recovery. Sodium and chloride are essential for hydration, helping your body hold water, regulate temperature, and maintain blood flow during and after exercise. Potassium also works inside the muscles to help with contraction, fluid balance, and glycogen recovery, and Magnesium supports energy production, reduces fatigue, and keeps muscles relaxed and functioning efficiently.
Research clearly shows that replacing electrolytes — especially sodium — before, during, and after intense or prolonged exercise can significantly improve endurance, reduce cramping and fatigue, and speed up recovery.
References
Savoie, F. A., Asselin, A., & Goulet, E. D. B. (2016). Comparison of sodium chloride tablets–induced, sodium chloride solution–induced, and glycerol–induced hyperhydration on fluid balance responses in healthy men. Journal of Strength and Conditioning
Research, 30(10), 2880–2891.
Wijering, L. A. J., Cotter, J. D., & Rehrer, N. J. (2022). Beverage sodium concentration and plasma volume during prolonged exercise in the heat. European Journal of Applied
Physiology, 122(6), 1401–1412.
Lindinger, M. I. (1995). Potassium regulation during exercise and recovery in humans: Implications for fatigue. Canadian Journal of Physiology and Pharmacology, 73(2), 220–223.
Cairns, S. P. (2023). Potassium and muscle fatigue: Cellular mechanisms and exercise implications. Sports Medicine, 53(11), 2331–2344.
Finstad, E. W., Newhouse, I. J., Lukaski, H. C., McAuliffe, J. E., Stewart, C. R., & Smith, M. J. (2001). The effects of magnesium supplementation on exercise performance and recovery in physically active women. Journal of Sports Medicine and Physical Fitness, 41(2), 165–172.
Cinar, V., Polat, Y., Baltaci, A. K., & Mogulkoc, R. (2006). Effect of magnesium supplementation on exercise performance and recovery. Biological Trace Element
Research, 111(1–3), 23–32.
