Electrolytes and sports hydration: what to take depending on intensity, climate and perspiration

October 5, 2025Editorial Team
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Electrolytes and sports hydration: what to take depending on intensity, weather, and sweating

Staying well hydrated is essential for performance, recovery, and overall health. But the choice of what to drink isn't always just water: electrolytes—especially sodium, potassium, chloride, magnesium, and calcium—play a key role in maintaining fluid balance, nerve conduction, and muscle function.

In this comprehensive guide, you'll learn how to choose rehydration drinks and strategies based on exercise intensity, weather conditions, and your sweating pattern. You'll find scientific explanations, practical recommendations, homemade recipes, and commercial options (including Foodelis products) to help you make evidence-based decisions that are easy to apply during training and competition.

Index

Why electrolytes matter

Electrolytes are minerals that dissociate into ions when in solution (e.g., in blood or sweat). They maintain fluid balance between compartments inside and outside cells, enable the transmission of nerve signals, regulate muscle contraction, and participate in acid-base balance.

During exercise, two processes occur that affect hydration and electrolytes:

  • Water loss through sweating, which reduces plasma volume if not replenished.
  • Loss of electrolytes (especially sodium and chloride) through sweat, which can alter osmolarity and muscle and neurological function.

Replacing only water after significant losses can dilute blood electrolytes and, in extreme cases, lead to hyponatremia. Therefore, the ideal strategy combines fluids and electrolytes adjusted to actual losses.

Main electrolytes and their function

Sodium (Na+)

It is the main extracellular cation. It regulates plasma volume and osmolarity and is key for water retention. Sodium is lost in varying proportions through sweat: some people have low losses (e.g., < 500 mg/L of sweat) and others very high losses (> 2000 mg/L).

Potassium (K+)

The main intracellular cation. Important for muscle function and nerve conduction. Less is lost through sweat than sodium, but it is still relevant for muscle recovery.

Chloride (Cl-)

It accompanies sodium and makes up most of the salt lost through sweat. It plays a role in water balance and maintaining acidity.

Magnesium (Mg2+) and calcium (Ca2+)

Magnesium supports muscle and nerve function; it also participates in enzymatic reactions. Its loss through sweat is less than that of sodium, but it can be significant in athletes with repetitive training loads or those on restrictive diets.

How sweating and weather affect it

The rate of sweating depends on the intensity and duration of exercise, acclimatization, clothing, body mass, and environmental conditions (temperature, humidity). In cold weather, the sweat rate may be low, but the cold does not eliminate the risk of dehydration if the activity is prolonged. In hot and humid weather, losses can be very high and sweat evaporation less efficient, increasing the risk of heat stress.

  • High temperature + high humidity = greater stress (abundant sweating and less evaporation).
  • High temperature + low humidity = increased sweating and better evaporation, but also rapid loss of water and electrolytes.
  • Low temperature = less sweating but possible water loss through respiration and prolonged exposure.

Sweating patterns also vary between individuals: some are "sodium losers" (salt-sweaters), while others have relatively low sodium concentrations in their sweat. Understanding your own pattern helps you customize your sodium replenishment.

Measure your sweat rate and sodium losses

Measuring perspiration rate is simple and very useful. Basic procedure:

  1. Weigh yourself without clothes or with minimal clothing just before training (pre-workout weight).
  2. Train for a known amount of time without drinking or with a measured amount of liquid.
  3. Weigh yourself immediately after finishing (post-workout weight).
  4. Calculate weight loss (pre - post). Subtract any fluids ingested and add the volume of urine if it occurred during training.
  5. Convert weight loss from kg to liters (1 kg ≈ 1 L). Divide by the training duration to obtain L/h.

Example: Net loss of 1.2 kg in 60 minutes = 1.2 L/h. If you drink 0.3 L during the session, total loss = 1.5 L/h (sum of drink + net loss).

There are simple methods and more precise methods for estimating sodium loss through sweat:

  • Practical method: assess the appearance of clothing (visible salt), frequent cramps, and need for additional salt. This serves as a guide, not an exact measurement.
  • Home methods: absorbent patches or sweat collectors commercially available to analyze sodium concentration.
  • Laboratory: sweat sample analysis for exact concentrations of Na+, K+ (ideal if you compete at a high level).

Using the sweat rate (L/h) and sweat Na+ concentration (mg/L) data, you can calculate the sodium loss per hour:

Sodium loss (mg/h) = sweat rate (L/h) × Na+ concentration (mg/L)

Example: 1.5 L/h × 900 mg/L = 1350 mg Na+/h.

What to drink depending on intensity and duration

Replenishment needs vary depending on the duration and intensity of the activity. A practical guide is provided below.

Light and short activity (<30 min)

Examples: gentle walks, yoga, low-intensity exercises.

  • Normal water is suitable for most people.
  • If it's very hot or if you're a salty sweater, consider having a drink with some sodium (100–300 mg/L) or a salty snack afterwards.

Moderate activity 30–60 min

Examples: easy running, recreational cycling.

  • For most people, water is sufficient if you drink according to your thirst and you are not in a very hot environment.
  • If you train in the heat or sweat a lot, use a sports drink with electrolytes and carbohydrates (3–6% carbohydrates, sodium 300–700 mg/L) to maintain energy and replenish sodium.

Intense or prolonged activity (>60 min)

Examples: running, cycling, triathlon, intensive team training.

  • Use solutions with carbohydrates (6–8% or as tolerated) and electrolytes. The recommended sodium intake in drinks during prolonged exercise is usually between 300–1200 mg/L depending on losses.
  • If your sweat rate is high and/or the concentration of sodium in your sweat is high, supplement with sodium tablets, salt in gels, or drinks with a higher sodium content per hour.

Exercises with frequent stops (team sport)

  • Drink small amounts of an electrolyte beverage during breaks.
  • Replenish sodium at the end of the session if you sweated a lot.

Recommendations based on climate and temperature

Cold climates

  • You may underestimate thirst; monitor fluid intake and weigh yourself during long sessions to check for losses.
  • If you don't sweat much, the risk of excessive sodium loss is low, but it's still important to stay hydrated. A low-concentration electrolyte drink (100–300 mg/L of sodium) may be sufficient.

Temperate climates

  • The replacement can follow the general guidelines according to duration and intensity.
  • Acclimation reduces the concentration of sodium in sweat over time, although the rate of sweating may increase.

Hot and/or humid climates

  • The likelihood of excessive sweating and sodium loss increases. It's common to need drinks with higher sodium content (500–1200 mg/L) and more fluids per hour.
  • Pay attention to high humidity: evaporation is less efficient, so thermoregulation becomes more difficult; replenishment must be regular and planned.

Homemade electrolyte recipes

Homemade recipes can work well if you prepare them carefully. Here are some options with simple ingredients.

Basic lemon and salt solution

  • 1 L of water
  • 1/4–1/2 teaspoon of salt (approx. 500–1000 mg of sodium depending on the type of salt)
  • 2 tablespoons of lemon juice (flavor and some potassium)
  • 1–2 tablespoons of honey or agave syrup (optional, for energy: 20–40 g carbohydrates)

Mix until dissolved. Adjust salt according to taste and tolerance.

Recipe with potassium (banana + salt)

  • 750 ml of water
  • 1 ripe banana, mashed (source of potassium)
  • 1/2 teaspoon of salt
  • 1 tablespoon of honey

Blend and strain if you prefer a lighter texture. This drink provides carbohydrates and potassium; helpful after long workouts.

Oral rehydration solution (balanced)

  • 1 L of water
  • 1/2 teaspoon of salt (approx. 1,000 mg sodium)
  • 3–4 tablespoons of sugar (15–20 g)
  • 1/4 teaspoon of baking soda (optional, helps with heartburn)
  • Lemon juice to taste

This mixture has a moderate osmolarity that facilitates absorption. It is similar to homemade rehydration solutions; it is not a substitute for a clinical solution in cases of severe dehydration.

Commercial products and when to use them

There are various options on the market: sports drinks, electrolyte sachets, effervescent tablets, saline gels, and powdered mixes. The choice depends on your fluid and sodium losses, carbohydrate preference, and gastrointestinal tolerance.

Types of products

  • Isotonic drinks: contain carbohydrates (3–8%) and electrolytes, designed for exercise of 45–120+ min.
  • Concentrated powders or sachets: adjustable mixtures according to the volume of water.
  • Effervescent tablets: practical for travel and short sessions; some have high sodium.
  • Tablets/saline tablets and sodium gels: for rapid sodium replenishment during long events.

When to choose a commercial product

  • Training/competitions > 60 min at moderate/high intensity.
  • Hot/humid climates with high sweating.
  • If you want precise sodium replacement based on your sweat rate.
  • If you need carbohydrates and electrolytes in a single product.

How to plan rehydration during training and competition

Proactive planning prevents performance losses and complications.

Step 1: Evaluate your sweating

Perform the weight test described above under representative conditions (same clothing, same weather conditions, same intensity) to determine L/h.

Step 2: Determine sodium concentration in sweat (if possible)

Use a simple test (patch or lab) to estimate mg/L of sodium. If you cannot measure, classify:

  • Low: < 450 mg/L
  • Moderate: 450–900 mg/L
  • High: > 900 mg/L

Step 3: Calculate how much sodium you need per hour

Multiply your sweat rate (L/h) by the sodium concentration (mg/L). If you don't know the concentration, you can estimate using ranges: 500 mg/L for moderate values, 1000 mg/L for high values.

Step 4: Choose the drink and the amount

  • If you lose 1 L/h, your sweat contains approximately 800 mg/L of sodium, resulting in a sodium loss of approximately 800 mg/h. In this case, using a beverage with 500–900 mg/L of sodium and/or adding a sodium tablet (e.g., 300–600 mg) every hour may be appropriate.
  • If you cannot drink at the required rate, prioritize sodium in concentrated form (tablets) and replace fluids when possible.

Step 5: Test and adjust

Test the strategy in training before using it in competition. Adjust for GI discomfort, taste, and sensations (dizziness, cramps).

Risks and safety

Most athletes benefit from planned replenishment. However, there are risks:

Dilution hyponatremia

Hyponatremia occurs when too much water is ingested without enough sodium, lowering the plasma sodium level. It is more common during ultra-endurance events or when pursuing excessive hydration goals. Signs include nausea, headache, confusion, and seizures. If you suspect hyponatremia, seek immediate medical attention.

Excess sodium

Consuming excess sodium occasionally during exercise is usually tolerated, but long-term, chronic excessive intake is not recommended for people with hypertension or other medical conditions. Consult your doctor if you have cardiovascular disease, kidney disease, or hypertension.

Gastrointestinal tolerance

Some drinks with concentrated carbohydrates can cause discomfort. Try different dilutions and products before competitions.

Frequently Asked Questions (FAQ)

Can I use water to replenish electrolytes after training?

Water helps replenish fluid volume, but it doesn't replace lost sodium. If the session was short and sweating was low, it may be sufficient. After long sessions or those with heavy sweating, it's better to combine water with salty foods or an electrolyte drink.

How much salt should I add to my homemade drink?

A good guideline is 1/4 to 1/2 teaspoon of salt per liter for light-to-moderate rehydration (approximately 500–1000 mg of sodium). Adjust according to your perspiration and taste.

Are carbohydrate drinks necessary?

For exercise lasting 60–90 minutes at moderate to high intensity, carbohydrate-rich drinks (6–8%) help maintain performance and delay fatigue. For short activities, energy intake is not a priority.

What if I get muscle cramps?

Muscle cramps aren't solely caused by electrolyte loss; neuromuscular fatigue and dehydration also play a role. Replacing sodium and fluids can help, but if cramps are frequent, consult a healthcare professional.

Can I rely solely on food (fruits, savory snacks) to replenish electrolytes?

For post-workout recovery, yes, fruits like bananas provide potassium, and salty foods replenish sodium. For quick replenishment during prolonged exercise, a drink or tablets are more practical.

References and suggested readings

The following is a list of scientific resources and practical guides. Many are reviews and consensus documents useful for further study.

  • American College of Sports Medicine (ACSM). "Exercise and Fluid Replacement" (position). Available at: ACSM Position Stand .
  • Baker LB. "Sweat composition: what does it tell us?" (revision). PubMed Search: PubMed: sweat sodium Baker .
  • Casa DJ, Armstrong LE, Hillman SK, et al. "National Athletic Trainers' Association position statement: fluid replacement for athletes." Available on PubMed: PubMed: fluid replacement athletes .
  • Popkin BM, D'Anci KE, Rosenberg IH. "Water, hydration and health." Nutr Rev. (hydration overview): PMC .
  • Sports Medicine reviews and consensus: PubMed searches on "sports hydration consensus" offer useful articles: PubMed: sports hydration consensus .

Note: The above references provide theoretical frameworks; modify the strategy according to individual response and consult with healthcare professionals in case of medical conditions.

Quick practical guide (actionable summary)

Scenery What to drink Practical tip
Activity <30 min, mild climate Water Hydrate according to your thirst; have a salty snack afterward if you sweat a lot
30–60 min, moderate heat Light isotonic drink (electrolytes) Low-to-moderate electrolytes; test before competing
>60 min, high intensity or heat Drink with carbohydrates + electrolytes (sodium 500–1200 mg/L) Calibrate by your sweat rate; use sodium tablets if necessary
Ultra-resistance Individualized plan: fluids, electrolytes, solid food Pre/post weight; training tests; avoid excessive overhydration

Conclusion

Smart hydration incorporates both water and electrolytes, adjusting to exercise intensity, duration, weather, and your individual sweating pattern. Measuring your sweat rate and, if possible, the sodium concentration in your sweat allows you to design a personalized and efficient strategy.

Use electrolyte drinks during long sessions or in the heat, consider commercial products like those from Foodelis for greater convenience and accuracy, and always test strategies in training before applying them in competition. If you have a medical condition, consult a healthcare professional before significantly increasing your sodium intake or taking supplements.

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