Most healthy runners, cyclists and pickleball players do not need a special electrolyte product for a 45-minute session. Sweat does remove sodium from your body, and long sessions in Southwest Florida heat can raise the stakes. But the best-supported advice is plainer than the marketing: match your drinking to your own sweat and session length, eat real food, and never drink more than you lose. Here is what the research says, where it disagrees with itself, and who should call a doctor first.
What do electrolytes do for runners and other athletes?
Electrolytes are minerals with an electric charge. MedlinePlus lists sodium as helping control the amount of fluid in the body and helping nerves and muscles work, and potassium and magnesium as helping the heart and muscles work properly. Its electrolytes page adds that you lose electrolytes when you sweat and that water alone has no significant amount of them.
That explains why electrolytes matter. It does not tell you how much you personally lose, or whether you need to replace it in the middle of a workout. The next sections take those two questions in turn.
How much sodium do you lose in sweat, and why does it vary?
Sweat sodium varies a great deal from person to person. A 2016 analysis of 506 athletes found predicted whole-body sweat sodium averaged about 36 mmol/L, with a range of 18 to 71 mmol/L. Sweating rates averaged 1.2 L per hour and ranged from 0.3 to 5.7 L per hour. Converting those figures (22.99 mg of sodium per mmol), the average works out to roughly 0.8 g of sodium per litre of sweat, and the range runs from about 0.4 g to 1.6 g.
A 2017 review by Baker lists what moves those numbers: exercise intensity, environment, heat acclimation, aerobic capacity, body size, sex, age, diet and hydration status. The same review notes that the sweat-testing method itself changes results. So a patch test or a sweat-test report is a useful estimate and not a fixed trait.
Heat matters for your location. A 2020 study of 556 athletes who live in a tropical climate measured sweat rates in training at a wet bulb globe temperature near 29 degrees C (about 85 F). Adult male endurance athletes averaged about 25 mL per kilogram per hour, which for a 70 kg runner is about 1.75 L an hour (my arithmetic). Naples summers are close to that kind of load, though the study group was athletes native to a tropical climate, so treat it as a ballpark.
Drink to thirst, or follow a plan?
Both are defensible, and they apply to different sessions. A 2018 review in Sports Medicine sorted the evidence by conditions, and the sorting is the useful part.
| Your session | What the review supports |
|---|---|
| Under 60 to 90 minutes, cooler weather, easy to moderate effort | Drinking to thirst is usually enough |
| Longer than 90 minutes, hot or humid, hard effort, or a performance goal | A planned amount, tested against your own sweat rate |
| Any session | Never drink so much that your weight goes up |
The tension is real. The American College of Sports Medicine's 2007 position stand recommends customized fluid plans, with a goal of avoiding more than 2% body weight loss, and notes that people differ widely in sweat rate and sweat electrolytes. The 2015 hyponatremia consensus (below) recommends drinking to thirst. The 2018 review reconciles them: when people drink purely by thirst they replace about half of what they lose, which keeps most people safe in short sessions, and a loss of 2% of body mass or more is where aerobic performance and heat tolerance start to suffer in many conditions.
Age changes the picture. The same review notes that thirst is less sensitive in the elderly, and Mayo Clinic says many older adults do not feel thirsty until they are already dehydrated. If you play pickleball in the morning heat and you are an older adult, lean toward a simple schedule rather than waiting for the signal.
How to measure your own sweat rate
A decision rule is only as good as your numbers, so measure them once.
- Weigh yourself before a typical session, with little clothing and after you urinate.
- Note how much you drink during the session.
- Dry off and weigh yourself again afterward.
- Weight lost plus the fluid you drank, divided by hours, is your sweat rate. For this purpose 1 kg of weight is treated as about 1 L of fluid, an approximation the 2018 review describes.
- Repeat on a hot day and a cool day. Your numbers will differ.
The ACSM stand names this same before-and-after weighing as the way to estimate an individual's sweat rate.
Can you drink too much? Exercise-associated hyponatremia
Yes, and it is the main reason "drink as much as you can" is poor advice. Exercise-associated hyponatremia (EAH) is a low blood sodium level that develops during or soon after activity. The 2015 international consensus statement concluded that the primary cause is overconsumption of hypotonic fluids, usually together with a hormone response that makes the body hold on to water, as summarized in a 2017 update by the same lead author. That update calls drinking beyond thirst the primary factor, whatever the sport.
Two details matter for what you buy. First, the update reports that sodium taken during a race may attenuate the fall in blood sodium but cannot prevent EAH if you overdrink, and the amount of fluid you drink drives the final blood sodium level more than the amount of sodium. Second, EAH is not only an ultramarathon problem: it has been reported in team sports, shorter races and yoga classes. A smaller group of cases involves athletes who lost weight, so sodium and volume loss may play a role for some people.
EAH also overlaps with heat illness, and the treatments differ. StatPearls says prompt differentiation is critical because isotonic fluids given for other exertional illnesses can worsen EAH. The takeaway for you is practical: more fluid is not automatically safer, and a person who is confused after a long, wet day needs a medical team instead of another bottle.
What are the signs of dehydration and heat illness?
Heat exhaustion is the milder condition, and heat stroke is an emergency. The CDC lists these symptoms of heat exhaustion: excessive thirst, profuse sweating, headache, dizziness or confusion, and nausea. Its advice is to get out of the sun, cool off and drink cool, non-alcoholic fluids such as water or sports drinks with electrolytes.
Heat stroke starts like heat exhaustion and then escalates. The CDC lists lack of sweating, body temperature reaching 106 F or higher within 10 to 15 minutes, and loss of consciousness, and says to seek medical help immediately. Its occupational-health page describes heat exhaustion as the body's response to an excessive loss of water and salt through sweating.
Use this as a quick check on a hot day:
- Stop and move to shade if you feel dizzy, nauseated, confused or get a headache with heavy sweating.
- Cool off and drink fluids; mild symptoms should ease.
- Call 911 if someone loses consciousness, stops sweating or feels very hot to the touch, the heat stroke signs the CDC lists.
Our guide to heat exhaustion symptoms goes into the detail and the first-aid steps.
Sports drinks, tablets or food for hydration?
Each does something different, and the evidence for each is uneven.
| Option | What the sources say | Limits |
|---|---|---|
| Sports drinks | The ACSM 2007 stand says drinks with electrolytes and carbohydrate can help compared with water alone under certain circumstances. | The ACSM's 1996 stand found little evidence of a difference from plain water in exercise under an hour. That is 30 years old. |
| Salt tablets or capsules | A 2015 study of ultramarathon runners found total sodium intake was unrelated to cramping, nausea, dehydration or hyponatremia in a 161-km race in the heat. | It is one race study of ultramarathoners. The ACSM's 2007 heat illness stand says cramps usually respond to rest and replacement of fluid and salt. The evidence is mixed. |
| Food and water | In a 1996 trial of 8 volunteers, water with a meal that supplied sodium and potassium restored fluid balance after exercise. | Small and 30 years old. It tested recovery after exercise and says nothing about mid-session needs. |
A 2017 review of post-exercise rehydration agrees on the broad pattern: large volumes of plain water produce a prompt increase in urine, adding sodium helps the body hold fluid, and carbohydrate and protein can help too. The ACSM's older 1996 position stand put sodium in a drink at 0.5 to 0.7 g per litre for exercise over an hour. That figure is 30 years old, and the 2007 stand moved to individual plans, so read any product label against your own sweat rate.
A reasonable approach for healthy recreational athletes: water for short sessions, a sports drink or salty food past about 90 minutes in the heat, and a real meal with fluids afterward.
Who should ask a doctor first?
Check with your doctor, before you add electrolyte products or change how much you drink, if any of these apply to you:
- Heart failure. MedlinePlus says too much sodium can lead to fluid retention in heart failure, that providers often set a sodium limit, and that they may adjust how much fluid you drink.
- Kidney disease. MedlinePlus says that if you have kidney disease you should talk to your provider before taking potassium supplements, so check the label of any electrolyte mix for potassium.
- Blood pressure medicines. The same page lists ACE inhibitors, angiotensin receptor blockers and potassium-sparing diuretics among the causes of high blood potassium. MedlinePlus also says adults with high blood pressure are usually advised to limit sodium, so a salty sports mix may not suit you.
- Water pills. Mayo Clinic notes that medicines such as water pills can raise the risk of dehydration in older adults.
Ask about anti-inflammatory pills too: the MedlinePlus heart failure page says NSAIDs such as ibuprofen and naproxen can cause the body to retain sodium.
What about IV hydration for athletes?
OutRecover's IV infusions are a medical service, given through its partner OutInfuse, and they require medical approval before a first visit, per the IV infusions page. For a healthy athlete, drinking is the standard way to rehydrate. Mayo Clinic says drinking more fluids usually fixes mild to moderate dehydration, and that severe dehydration needs medical treatment right away.
The sources in this guide make no case that an IV rehydrates a healthy runner better than drinking and eating, and we are not making one. For what research exists on one popular drip ingredient, see our guide to NAD IV therapy.
Where studio services fit
None of OutRecover's services is an electrolyte or hydration treatment, and none changes how much sodium you sweat. What the studio offers is recovery support around the training itself. The OutTrain package is built for runners, cyclists and endurance athletes and bundles recovery sessions. It is not a hydration plan. If you are coming off a long race, our marathon recovery guide covers the days that follow, and fluid and food are part of them.
Your next step
Run the sweat-rate check once on a hot day this week. Then decide: if your session is under 90 minutes, drink to thirst and eat a normal meal afterward. If you go longer in the heat, write down a plan that matches your numbers, test it in training, and never drink so much that your weight goes up. If you have heart or kidney disease or take blood pressure medicine, bring this list to your doctor before you change anything.
Sources
- American College of Sports Medicine (Sawka et al.). American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine and Science in Sports and Exercise, 2007. https://pubmed.ncbi.nlm.nih.gov/17277604
- Hew-Butler et al. Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015. Clinical Journal of Sport Medicine, 2015. https://pubmed.ncbi.nlm.nih.gov/26102445
- Hew-Butler, Loi, Pani, Rosner. Exercise-Associated Hyponatremia: 2017 Update. Frontiers in Medicine, 2017. https://pmc.ncbi.nlm.nih.gov/articles/PMC5334560
- Baker LB. Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability. Sports Medicine, 2017. https://pubmed.ncbi.nlm.nih.gov/28332116
- Baker et al. Normative data for regional sweat sodium concentration and whole-body sweating rate in athletes. Journal of Sports Sciences, 2016. https://pubmed.ncbi.nlm.nih.gov/26070030
- Rivera-Brown and Quinones-Gonzalez. Normative Data for Sweat Rate and Whole-Body Sodium Concentration in Athletes Indigenous to Tropical Climate. International Journal of Sport Nutrition and Exercise Metabolism, 2020. https://pubmed.ncbi.nlm.nih.gov/32454460
- Kenefick RW. Drinking Strategies: Planned Drinking Versus Drinking to Thirst. Sports Medicine, 2018. https://pmc.ncbi.nlm.nih.gov/articles/PMC5790864
- Centers for Disease Control and Prevention. Heat Illnesses. Travelers' Health, reviewed June 25, 2024. https://wwwnc.cdc.gov/travel/page/heat-illnesses
- Centers for Disease Control and Prevention, NIOSH. Heat-related Illnesses. https://www.cdc.gov/niosh/heat-stress/about/illnesses.html
- MedlinePlus (National Library of Medicine). Fluid and Electrolyte Balance. https://medlineplus.gov/fluidandelectrolytebalance.html
- MedlinePlus Medical Encyclopedia. Electrolytes. https://medlineplus.gov/ency/article/002350.htm
- Buck, McAllister, Schroeder. Exercise-Associated Hyponatremia. StatPearls, 2023. https://pubmed.ncbi.nlm.nih.gov/34283494
- Hoffman, Stuempfle, Valentino. Sodium Intake During an Ultramarathon Does Not Prevent Muscle Cramping, Dehydration, Hyponatremia, or Nausea. Sports Medicine Open, 2015. https://pubmed.ncbi.nlm.nih.gov/26709371
- American College of Sports Medicine (Armstrong et al.). Exertional heat illness during training and competition. Medicine and Science in Sports and Exercise, 2007. https://pubmed.ncbi.nlm.nih.gov/17473783
- Maughan, Leiper, Shirreffs. Restoration of fluid balance after exercise-induced dehydration: effects of food and fluid intake. European Journal of Applied Physiology, 1996. https://pubmed.ncbi.nlm.nih.gov/8781863
- Evans, James, Shirreffs, Maughan. Optimizing the restoration and maintenance of fluid balance after exercise-induced dehydration. Journal of Applied Physiology, 2017. https://pubmed.ncbi.nlm.nih.gov/28126906
- American College of Sports Medicine (Convertino et al.). Exercise and fluid replacement (position stand). Medicine and Science in Sports and Exercise, 1996. https://pubmed.ncbi.nlm.nih.gov/9303999
- Mayo Clinic. Dehydration: Symptoms and causes. https://www.mayoclinic.org/diseases-conditions/dehydration/symptoms-causes/syc-20354086
- MedlinePlus Medical Encyclopedia. Heart failure: fluids and diuretics. https://medlineplus.gov/ency/patientinstructions/000112.htm
- MedlinePlus Medical Encyclopedia. Potassium in diet. https://medlineplus.gov/ency/article/002413.htm
- MedlinePlus Medical Encyclopedia. Sodium in diet. https://medlineplus.gov/ency/article/002415.htm
