Electrolytes
Electrolytes replace what you sweat out. Sodium in sweat averages around 800 to 1000 mg per litre in athletes, with wide individual variation from roughly 400 to 1600 mg per litre.
What the research shows
Mixed or small evidence. The effect is uncertain.
Most of the research measures the loss, without measuring what a supplement delivers. Baker (2016) and Rivera-Brown (2020) mapped sweat loss and sweat sodium in 506 and 556 athletes: useful reference values without a performance outcome, and Baker's work was paid for by the Gatorade Sports Science Institute. The two randomised trials with a performance outcome point in different directions. Del Coso (2016) saw 26 triathletes complete a half ironman faster on salt capsules, while Cosgrove (2013) found no difference over 72 kilometres at 14 degrees in nine cyclists taking 700 milligrams of salt per hour. Small, mixed evidence resting largely on a surrogate measure lands on thin evidence by our standard.
Who it makes sense for: Worth it for efforts longer than two hours in the heat, for heavy sweaters and for people with salty sweat: triathlon, marathon, ultra running and summer cycling. For an hour of training in a cool gym no gain has been demonstrated. Watch the amount as well: the trial that did find an effect used around 2.6 grams of sodium across a whole race, many times the few hundred milligrams in a pre-workout serving.
How we weigh evidenceClinical dosage
Origin
Natural & syntheticElectrolytes (sodium, potassium, magnesium, calcium) are naturally present in virtually all foods. Sodium is in salt, potassium in bananas and potatoes, magnesium in nuts and leafy greens. In supplements often added as mineral salts.
Safety
The amount per serving is a practical choice, since no study makes a statement about it. People who sweat heavily and saltily need more than average. The largest dataset comes from the Gatorade Sports Science Institute, part of PepsiCo. An independent study of 556 athletes in a tropical climate arrives at comparable values.
For comparison
One hour of intense exercise can cost you 500-1,500mg of sodium through sweat, comparable to half to one teaspoon of salt. A banana contains about 400mg of potassium, a sports drink usually 100-200mg of sodium per serving.
Dosage by weight and gender
Electrolyte needs depend on your sweat rate, not just weight. Heavier athletes (>80kg) tend to sweat more. Guideline: 500-1,000mg sodium per hour of intense exercise, 200-400mg potassium, 100-200mg magnesium (Sawka et al., 2007). Women sweat less on average, so needs may be slightly lower.
Frequently asked questions
What are electrolytes?
Electrolytes are minerals with an electrical charge, such as sodium, potassium, magnesium, and calcium. They regulate fluid balance, muscle contractions, and nerve signals. You lose them through sweat, which can lead to cramps and reduced performance if not replenished.
Are electrolytes dangerous?
At normal sports dosages, electrolytes are completely safe. Excessive sodium intake can raise blood pressure. Too much supplemental potassium (>2,500mg) can be dangerous for people with kidney problems. Stick to recommended doses.
When should I take electrolytes?
During workouts longer than 60 minutes or in high temperatures. Take them before and during training. For short workouts (<45 minutes) in cool conditions, water is usually sufficient. Pay extra attention if you sweat heavily.
Scientific sources
The clinical dosages on this page are based on peer-reviewed research.
- Normative data for regional sweat sodium concentration and whole-body sweating rate in athletesBaker LB et al. (2016)Funded by: Gefinancierd door het Gatorade Sports Science Institute; de eerste auteur was daar in dienst. Gatorade hoort bij PepsiCo en verkoopt sportdranken met elektrolyten.
- Normative Data for Sweat Rate and Whole-Body Sodium Concentration in Athletes Indigenous to Tropical ClimateRivera-Brown AM et al. (2020)
- Effects of oral salt supplementation on physical performance during a half-ironman: A randomized controlled trialDel Coso J et al. (2016)
- Sodium supplementation has no effect on endurance performance during a cycling time-trial in cool conditions: a randomised cross-over trialCosgrove SD et al. (2013)Funded by: Betaald door de University of Otago. De auteurs verklaren geen concurrerende belangen.
Pre-workouts with Electrolytes
We keep the dosages and values on this page as accurate as possible based on selected studies. New research may change these values. Nothing on this page is medical advice. If you have any doubts, always consult a doctor.