Walk through any expo the day before a marathon, ultramarathon, or long-course triathlon and you’ll see athletes sipping concentrated electrolyte drinks, tossing back salt capsules, and asking the same question: should I be loading sodium before the gun goes off?
It’s a strategy borrowed from elite endurance athletes, and over the past few seasons it has trickled down to weekend warriors prepping for spring marathons and summer ultras. The pitch is simple: top off your sodium tank before you start sweating so you delay the dreaded mid-race wall, cramping, and fade. But does it actually work — and is it worth the tradeoffs?
Here’s what current research and practitioner experience suggest, plus how to figure out if pre-loading belongs in your race-day playbook.
What Is Sodium Pre-Loading?
Sodium pre-loading (sometimes called “salt-loading” or “electrolyte pre-loading”) is the practice of consuming a higher-than-usual dose of sodium in the hours before — and sometimes the days before — a long endurance event. Typical protocols range from a single concentrated drink the morning of the race to a multi-day taper where athletes deliberately salt their food more heavily and sip salty broths.
The most common modern version: roughly 60–90 minutes before the start, athletes drink 16–20 ounces of fluid containing 1,000–1,500 mg of sodium. Brands like Precision Fuel & Hydration popularized this with their PH 1500 pre-load drinks, and LMNT’s Recharge mix has become a similar staple at start lines across the country.
The theory is straightforward: by elevating plasma sodium and total body fluid before the race, you start with a buffer that helps maintain blood volume, delay dehydration-related slowdowns, and keep electrolyte balance in check during the early miles.
What the Science Says
Research on pre-loading is encouraging but nuanced. A frequently cited 2010 study published in the International Journal of Sport Nutrition and Exercise Metabolism found that sodium-loaded athletes increased their plasma volume and performed better in a hot-weather time trial than control athletes. More recent reviews — including a 2025 narrative review on hydration strategies in ultra-endurance running — suggest that hybrid approaches that combine sweat-rate testing, individualized sodium intake, and attention to thirst cues outperform one-size-fits-all hydration plans.
The mechanism is real: sodium pulls water into the bloodstream and helps preserve plasma volume, which supports cardiovascular function and thermoregulation under heat stress. Athletes who under-hydrate or under-salt before a hot race are starting from behind.
That said, pre-loading isn’t magic. For a flat marathon in cool conditions, when an athlete already eats salty foods and uses sports drinks during the race, the marginal benefit may be small. The bigger payoff shows up in hot weather, longer events (50K and beyond), and for athletes who lose a lot of sodium in their sweat — the so-called “salty sweaters” who finish workouts with white salt rings on their hats and shirts.
Who Actually Benefits
Not every endurance athlete needs to pre-load. The strategy makes the most sense for four groups:
Salty sweaters. If your race singlet ends up crusty with salt, you’re likely losing 1,000+ mg of sodium per liter of sweat. Pre-loading helps offset what you’ll dump during the race.
Hot-weather racers. Spring marathoners hitting unseasonably warm Boston or Big Sur conditions, summer 50K runners, and Hawaii-bound triathletes face heat that compounds sodium losses. Pre-loading buffers that hit.
Long-course athletes. The longer the event, the more cumulative sodium loss matters. A 4-hour marathoner will lose less total sodium than a 12-hour Ironman athlete or a 100-mile trail runner, where mid-race deficits compound mile after mile.
Athletes prone to cramps or late-race fade. If you’ve had bonks, dizziness, or end-of-race issues that didn’t respond to plain water, your sodium intake — both pre-race and during — is likely the lever worth experimenting with.
For shorter races (5K to half marathon) or cool, low-effort outings, normal hydration habits and a slightly salty pre-race meal are usually enough.
Common Pre-Load Options
Athletes have plenty of choices for pre-loading, and each has tradeoffs.
Concentrated electrolyte drinks like Precision Hydration’s PH 1500, LMNT Recharge, Skratch Labs Sport Hydration Mix (high-sodium version), and Nuun Endurance offer measured doses with no guesswork. They’re the most reliable option but cost more per serving.
Pickle juice and other fermented brines have become a darling of the cramp-prone crowd. Pickle juice is rich in sodium, easy to find, and packs a flavor punch some athletes love before a long effort. Brands like Fast Pickle are popular with athletes who want a clean, concentrated hit of sodium without artificial dyes or sweeteners — and the high-sodium pickle juice format slots neatly into a pre-race routine for runners who’d rather drink something savory than sweet.
DIY salt-water mixes. A homemade pre-load using sea salt, water, and a splash of fruit juice or a pinch of stevia works fine for athletes on a budget. Aim for about 1,000 mg sodium per 16 oz of fluid, and don’t skip a flavor agent — straight salt water is brutal on an empty stomach.
Salty foods. A bowl of miso soup, a salty bagel with lox, or a couple of pickles with breakfast will modestly raise your sodium intake without requiring a separate drink. This won’t reach the 1,000+ mg threshold of a dedicated pre-load drink, but it’s better than nothing for athletes who don’t tolerate liquid loading on race morning.
How to Test It Before Race Day
The cardinal rule of race nutrition applies here: never try anything new on race day. If pre-loading is on your radar, dial in the protocol during a long workout in conditions similar to your race. Try the same drink, the same volume, the same timing — and see how your stomach handles it during a hard 90-minute or 2-hour effort.
A simple test plan: at one of your final long-run weekends, drink 16–20 oz of a high-sodium electrolyte mix 60–90 minutes before the run, then continue normal in-run hydration. Note how you felt — energy, GI comfort, urge to pee at mile 3 — and adjust the dose, timing, or product accordingly. If you cramped or felt depleted late in the workout, the pre-load probably wasn’t enough. If your stomach rebelled, you may need a smaller volume or a different format (capsules instead of drink, or salty food instead of liquid).
A Word on Going Too Far
Sodium isn’t a free lunch. Pre-loading too much, too far ahead of a race can leave you running to the bathroom at the start line — your kidneys will pull excess sodium and fluid back out before you even toe the line. And athletes with high blood pressure, kidney conditions, or heart disease should talk to their doctor before adopting a pre-loading protocol.
Pre-loading is also not a substitute for in-race hydration. Even the best pre-load won’t carry you through 26 miles in 80-degree heat without continued sodium and fluid intake during the event.
The Bottom Line
Sodium pre-loading is a legitimate tool for endurance athletes racing in heat, going long, or losing big amounts of sodium in their sweat. For everyone else, it’s a nice-to-have, not a must-have. The data supports its physiological benefits, but the magnitude of benefit depends on your sweat profile, your race conditions, and your usual diet.
Pick a format you can actually stomach 60–90 minutes before a hard effort — whether that’s a clinical electrolyte drink, a glass of pickle juice, or a salty bowl of broth — and test it before race day. The athletes who race well aren’t necessarily the ones using the fanciest products. They’re the ones who know exactly how their body responds to their fueling plan.