Featuring guidance from Marni Sumbal, MS, RD, CSSD

As an endurance athlete, you already know that hydration matters. What changes after 35 is how quickly things can go wrong, and how long it takes to recover when that happens.

Reliable cramps at mile 18 that didn’t happen when you were 25. Legs feeling flat after 90 minutes even though you’ve been hydrating. Still recovering from Saturday’s steady distance workout on Monday morning. Often times, it’s because of electrolytes. Specifically, whether you’re replacing sodium and fluid at the rate your body is losing them.

Whether you’re exercising in the cold, preparing for a marathon, or logging endurance miles, electrolytes can help prevent fatigue, cramps, and energy dips.

There’s evidence that thirst signals become less reliable with age. That means masters athletes often need to pay more attention to hydrating based on timing rather than thirst cues. For heavy sweaters, the gap between what you lose and what you replace can get wide really fast.

We tested these products on long runs and rides, both outdoors in warm weather and indoors. The picks below reflect what performed best for us.

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What Masters Athletes Should Know About Electrolytes

Most electrolyte advice caters to a generic fitness audience. But after 35, your needs and demands will likely change.

“Being a masters athlete doesn’t make fueling less important. If anything, it matters more,” says Marni Sumbal, MS, RD, CSSD, a board-certified sports dietitian, author of Essential Sports Nutrition, and 22x Ironman finisher. “As the body responds differently to training stress with age, proper sports nutrition is essential to support strength and intensity. Correct fueling is the difference between feeling depleted and feeling strong and capable.”

It’s easy to overlook or ignore proper hydration. Sumbal identifies dehydration as one of the three most common reasons athletes bonk mid-race, noting that the symptoms — dizziness, fogginess, sudden weakness — are frequently mistaken for running out of fuel. The fix isn’t always more carbohydrates. Sometimes it’s replacing sodium and fluid earlier than you think.

Like energy gels, electrolyte powders come in many flavors and varieties. They also vary widely in sodium content, ingredients, and sweetness.

What to Look for in an Electrolyte Powder

Here are the key ingredients to keep in mind for your training and sweat rate in this age range:

Sodium – the most important electrolyte

Sodium is the primary electrolyte lost in sweat and the most critical one to replace. It’s difference between staying functional late into a race or fading. Products on this list range from roughly 200mg per serving (Nuun Sport) to 1,000mg (LMNT).

Generally, masters athletes should aim to replace one gram per hour. But individual needs vary. This sweat and sodium loss calculator can help you find your ideal range.

Potassium & Magnesium

Potassium and magnesium are considered secondary (but still useful). Your sweat contains small amounts of magnesium, calcium, and potassium. Potassium helps with fluid balance while magnesium supports muscle function.

Sugar vs. No-Sugar Electrolytes

Some electrolyte powders include added sugars, but others don’t. Your needs may depend on the type and duration of activity, along with your personal preferences. Keep in mind that blood sugar spikes can lead to energy crashes and fading too soon.

Ingredient Tips for Sensitive Stomachs

Sumbal suggests hydration powders with minimal ingredients — sodium and glucose/sucrose as the base. Avoid formulas with high citric acid content or magnesium citrate/oxide, which can be harder to digest during heavy efforts. Avoid artificial sweeteners and excess fructose, such as sucralose or stevia, if you’ve had GI issues in races.

Electrolytes for Recovery

Long after a race or hard workout, your body is still losing fluids and electrolytes. Several products on this list work equally well for recovery.

The Best Electrolyte Powders to Maximize Training & Performance

As endurance runners and cyclists, we’ve tested several electrolyte powders. Right now, we use Skratch Labs on long rides and runs, and during Peloton endurance classes. After hard workouts, we refresh with Liquid I.V.

Just as the best protein powders for athletes vary based on individual needs and preferences, hydration is also personal. Dietary restrictions, sweat rates, and training styles are important to consider. Running and cycling may require different approaches, but one rule always applies: don’t try a new electrolyte powder for the first time on race day.

1. LMNT ($45.00) — Best Electrolyte Powder for Heavy Sweating

If you finish rides or runs with salt stains on your shirt, start here. LMNT delivers 1,000mg of sodium per stick, and it tastes as salty as it sounds. We use it most in hot weather, on long runs and rides, and during hard, sweaty long bike trainer workouts. Each stick also adds 200mg of potassium and 60mg of magnesium malate, a form that’s easy on the stomach.

With no sugar and just 1g of carbs, it won’t fuel you, so pair it with gels or chews for anything over 60–90 minutes. Sensitive to stevia? The Raw Unflavored version is sweetener-free.

2. Skratch Labs Hydration Mix ($35.95) — Best for Cyclists & Runners

Our go-to for rides of 45+ miles and long runs. Each scoop delivers 19g of carbs from cane sugar and dextrose plus 400mg of sodium. The flavor comes from real fruit, not stevia, and it’s been easy on our stomachs over long efforts. It won’t fully replace gels on longer days, since two scoops an hour is about 38g of carbs, but it means fewer gel stops.

But it doesn’t dissolve easily. Give it a hard shake, and expect some clumping as it settles. It contains citric acid, so test it in training if your stomach is sensitive.

3. Precision Hydration Electrolyte Capsules ($9.99) — Best for Cramping

Precision Hydration’s SweatSalts let you take sodium with plain water, which can reduce cramping without risky GI issues. Each capsule delivers 250mg of sodium with no sugar, sweeteners, or citric acid. These vegetarian capsules are also batch tested against the WADA prohibited list. Take one to four per hour depending on how much you sweat and how hot it is. Since there are no carbs, you’ll still need gels or chews to fuel longer efforts.

4. SALTT Electrolyte Packets ($39.00)

SALTT has nearly the same sodium as LMNT (968mg vs. 1,000mg per stick) and also skips the sugar, citric acid, and maltodextrin that can upset your stomach. Each stick also adds 409mg of potassium and 178mg of magnesium, about three times LMNT’s.

The magnesium comes from sea salt as magnesium chloride, a gentler form than the citrate or oxide in many hydration mixes. That’s useful if your diet runs low, but a higher dose can cause GI issues, so start with one stick and test it before race day.

There are no carbs, so pair it with gels or chews for anything over 60–90 minutes. Mix each stick into at least 16 ounces of cold water for a less salty flavor.

5. Nuun Sport ($27.38) — Best for Traveling

A tube of Nuun tablets fits into a jersey pocket or waist pack, and there’s no scooping or clumping. Using one tube instead of a stack of single-serve sticks also cuts down on packaging. Each tablet has 300mg of sodium, enough for shorter sessions but light for long or hot efforts. We’ve tried every flavor and liked them all, especially Tri-Berry.

If you have GI sensitivities, test them in training first. If you have GI sensitivities, test them in training first. Citric acid is the main ingredient, and the fizz can cause bloating.

6. Tailwind Endurance Fuel ($22.05)

Tailwind packs more than twice the carbs of Skratch: 50g per sachet, plus about 600mg of sodium. One bottle can cover both fuel and hydration for an hour of steady effort, so you can ditch gels and chews on longer runs and rides.

The carbs come from dextrose and sucrose, a blend that’s easier to absorb than a single sugar, with no stevia or artificial sweeteners. Sip it every 10–15 minutes rather than gulping. Mid-effort, your gut can only absorb so much sugar at once, and the excess can cause bloating or cramping.

Two flavors (Tropical and Raspberry) contain 70mg of caffeine, so check before buying if you’re sensitive.

7. REDMOND Re-Lyte Hydration Electrolyte Powder Mix ($44.99)

Another strong pick for heavy sweaters, Redmond Re-Lyte delivers 810mg of sodium per scoop from Redmond Real Salt, plus 400mg of potassium and 50mg of magnesium in gentler glycinate and malate forms. It’s Informed Choice certified for banned substances.

However, it contains citric acid, which can cause GI upset. And with no carbs, you’ll still need gels or chews on longer efforts. If it tastes too salty, start with half a scoop or add more water.

8. THORNE Daily Electrolytes ($40.00)

Another good option if you prefer saltier formulas. This one has 480mg of sodium per serving, which makes it ideal for warm weather and prolonged endurance workouts. However, it may be too salty for shorter workouts where you aren’t sweating heavily. The zero added sugars is a bonus, especially if you’re trying to avoid excess sugar.

9. Hi-Lyte K1000 Electrolytes Powder Mix ($33.96)

Can’t stand the taste of most electrolyte powders? This unflavored mix has no overwhelming taste or aftertaste. It’s high in potassium (1,000mg) per serving and contains no sugar, gluten, or artificial ingredients. However, heavy sweaters should note the minimal sodium content.

10. Liquid I.V. Hydration Multiplier ($23.46)

Our go-to after a long, sweaty run or ride. Each stick has 500mg of sodium and 11g of cane sugar and dextrose. Glucose helps your body absorb sodium and water faster, so you rehydrate more quickly than with water alone. But it’s not a full recovery drink. There’s no protein, and 11g of carbs won’t refill glycogen after a hard effort, so pair it with a protein shake or a real meal. If citric acid bothers your stomach, save it for after your workout rather than during.

FAQs

How can athletes tell if they’re dehydrated?

Common signs include dark yellow urine, cramping, fatigue, headaches, and difficulty concentrating during effort. Sumbal cautions that dizziness, fogginess, and sudden weakness mid-race are frequently mistaken for bonking — running out of fuel — when dehydration is actually the culprit. It’s important to distinguish the two since gels won’t solve a sodium and fluid deficit.

How much electrolytes do endurance athletes actually need?

For workouts under 60 minutes in mild weather, water is usually sufficient. Between 60 and 90 minutes, electrolytes start to help. Over 90 minutes — especially for heavy sweaters or racing in heat — electrolytes and carbohydrates support performance better than plain water. Sumbal explains, “A practiced plan for both the days leading up to the race and race day itself is vital to avoid guesswork.” That includes your hydration strategy, not just your food.

What’s the best electrolyte powder for marathon or ultra-distance runners?

Higher sodium and carbohydrates are best for long-distance runners and other endurance athletes. LMNT (1,000mg sodium, no carbs) works well for athletes who want to manage fuel and hydration separately. Skratch Labs (380mg sodium, 20g carbs) supports both. For runners with sensitive stomachs, Precision Hydration tablets are worth considering. The taste is neutral and it’s easy to dial in by sodium concentration.

Do cyclists and runners need different electrolytes?

Format and carbohydrate tolerance often differ by discipline. “Always experiment to see which foods sit best for different disciplines,” Sumbal explains. “Run fueling often differs from cycling or swimming.” Cyclists generally tolerate carbohydrate-heavy mixes more easily, and it’s easier to drink on the bike. Runners, particularly those with sensitive stomachs, often do better with lighter, lower-sugar formulas. Triathletes should test run and bike nutrition separately in training.

What should I look for in a cleaner electrolyte formula?

Look for shorter ingredient lists. The products on this list with the fewest additives are LMNT, REDMOND Re-Lyte, and Micro Ingredients. For GI-sensitive athletes, Sumbal suggests sodium and glucose/sucrose as the base, and avoid high citric acid content or magnesium citrate/oxide.

Should I take electrolytes before, during, or after training?

If it’s warm, just half a serving 30-60 minutes before longer efforts can help you start ahead of your losses. During 60-90 minute efforts, consistent small amounts beat a large dose taken too late. After hard sessions, try to rehydrate with sodium and a small amount of carbohydrates.

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