Featuring guidance from Marni Sumbal, MS, RD, CSSD — board-certified sports dietitian and 22x Ironman finisher

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 often finish rides or runs with salt stains on your shirt, the LMNT electrolyte drink mix could be a good choice. It’s packed with sodium (1,000mg per serving) and tastes as salty as it sounds. We find it works best in hot weather, endurance runs and rides, and long bike trainer workouts. This low-carb formula also delivers 200mg of potassium and 60mg of magnesium per serving.

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

Skratch Labs Sport Drink Mix is our go-to choice for long endurance rides of 45+ miles and distance running. It tastes good, is easy to digest, and simplifies fueling. No need for mid-ride gel stops. However, it’s not the easiest to mix. It requires a good shake and can clump as it settles.

3. Precision Hydration 1000/1500 ($11.99) — Best for Endurance Athletes

Like the LMNT electrolyte packets, the Precision Hydration tablets are best for heavy sweating. You also have more control over the amount of sodium you consume. These tablets range from 500-1,500mg, and you can adjust intake based on sweat rate. They’re ideal for long workouts and races, intense training blocks, and fine-tuning your performance.

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

Highly portable and easy to stash in a jersey pocket or waist pack, these Nuun tablets travel easily. Plus, the individual tablets reduce packaging waste. We’ve tried every flavor liked them all, especially Tri-Berry. If you have GI sensitivities, just note that these tablets fizz when mixed with water.

5. Tailwind Endurance Fuel ($22.05)

As with Skratch Labs, the Tailwind Endurance Fuel formula is carb-heavy. That makes it a great choice for long-distance athletes who prefer to ditch the gels and chews for one simple solution for hydration and calories. To avoid potential GI upset, try taking small sips of this formula as you go.

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

REDMON Re-Lyte hydration mix, another good option for heavy sweaters, features Redmond salt and a handful of other clean ingredients. However, the 810mg of sodium per serving might be too concentrated. If needed, start with half a scoop or add more water to find a good balance.

7. Micro Ingredients Electrolyte Powder ($34.95)

The cleanest formula on this list, with just a few all-natural ingredients like lemon juice powder and coconut water powder. It’s also light on salt but heavier on potassium and magnesium, making it a good choice for everyday training and lighter sweaters. Unfortunately, it’s not sold in individual packets.

8. 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.

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

Our go-to hydration pick after a long run or ride. This refreshing lemon lime formula blends easily with water and is packed with vitamins and nutrients to support recovery. However, flavor choices are limited compared to some other electrolyte powders on this list.

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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