For most of us, salt falls into the same category as sugar—it tastes great but we should be eating less of it. Skipping the shaker can keep your heart healthy and, vainly, it’ll minimize bloating and optimize the work you’ve put in at the gym.
But chances are, if you’re reading this (and therefore perusing websites and magazines on eating healthy and getting fit), you probably don’t need to forgo the mineral.
“Most Americans consume too much salt, but I’d bet men and women who pay attention to their diet and fitness are probabaly consuming too little salt, actually,” says sport physiologist Alex Harrison, Ph.D., a performance consultant at Renaissance Periodization.
And spurning sodium may actually be compromising your athletic performance—even if you’re not running marathons or hitting two-a-days.
“Endurance athletes are notorious for under-consuming sodium, but it’s becoming more inclusive with the gym/HIIT group and ‘clean-eating’ camp,” says exercise physiologist and nutrition scientist Stacy Sims, Ph.D, senior research fellow at the University of Waikato in New Zealand.
If your go-to sweat session is in the weight room or CrossFit box, a sodium deficiency can actually make your muscles weaker, workouts harder, and dehydration worse. Here’s why.
How Sodium Makes Or Breaks Performance
Low total-body sodium can lead to hyponatremia (water intoxication—“common in gym-goers who are ‘super clean’ and drink excessive tea, water, or non-sodium containing drinks,” Sims says), GI distress (loss of appetite, nausea, vomiting), neural issues (muscle spasms or twitching that won’t go away, muscular weakness), and extreme headaches, she explains.
When it comes to athletic performance, low-sodium causes two main problems: It leaves you dehydrated and weakens your muscles.
Quick refresher on how dehydration works: Sodium helps retain fluid in the body, specifically blood plasma volume.
“When sodium is low, dehydration results and the heart has to work harder to accomplish the same amount of work,” Harrison explains.
If your sodium stores are low enough to cause moderate dehydration—losing 2 to 4% of your body weight—it’ll tax your heart enough to affect physical performance, he says.
Aerobic performance (read: cardio) is hit first since it requires more immediate blood pumping.
But over time, “one’s ability to recover from repeated anaerobic bouts of exercise (like multiple sets in the weight room) will start to be compromised,” Harrison adds.
The decreased blood volume and higher heart rate take their toll. What’s more, the side effects of dehydration include dizziness and fatigue, which can seriously put you at risk when you’re trying to maneuver heavy plates and dumbbells.
The other hitch: Sodium is critical for nerve conduction. Without enough of the element, the electrical signals in your body slow down, which means your muscles can’t fire as quickly and the fibers won’t contract.
“This makes the actual muscle ‘weaker’ in the work that it does, which translates to feeling fatigued and weak in a workout,” says Sims.
Plus, slower signaling means a slower flood of the nutrients that help regenerate muscle (potassium, calcium, sodium), which leads to slower bounce back. In other words, you won’t be able to go as hard or heavy, set after set, in the weight room.
Who Exactly Needs More Salt?
For endurance athletes, supplementing the stuff is a no-brainer. The more (and longer) you sweat, the more sodium you’re losing. Harrison estimates around 75% of the distance athletes he works with are under-consuming salt for their activity level (which falls around six to 20 hours per week). Adding more back in would help: A 2016 study in The Scandinavian Journal of Medicine & Science in Sports found amateur triathletes improved both their finish time and reduced their body mass loss when they took a salt supplement before and during a half-Ironman.
But even men who are just working out 3 to 5 hours per week don’t need to be limiting their salt since “they’re already on the low end of what’s acceptable, or just mildly under-consuming salt,” Harrison adds. And same goes for guys who prefer throwing weights around. In fact, a recent study in the Journal of the International Society of Sports Nutrition found when high-intensity strength athletes increased their water and electrolyte consumption (based on their personal sodium loss), they were able to exert more anaerobic power, recover faster, and improve attention and awareness.
So How Much Sodium Should You Aim For?
Both experts agree there isn’t a one-size-fits-all recommendation for salt intake. Unlike protein or carb consumption, “it varies enormous amounts with temperature, exercise type and duration, clothing type, and simply genetics of sweat ion concentration,” Harrison explains. For some, 1,000 to 1,500 mg may be ideal, while for others, 10,000 mg still may not be enough on a very long, hot endurance-training day. And your needs are totally different day to day, Sims points out.
The good news is odds are low you’ll overdo it. Research shows only people with high blood pressure need to worry about limiting their salt intake and Harrison adds your kidneys will clean house and excrete the excess sodium if you over-consume, especially among healthy folks.
He advises aiming for at least 1500 mg of sodium on all training days that clock in under an hour. Longer than that, Harrison recommends hitting 2300 mg that day, closer to 4000+ mg if you’re sweating for more than two hours.
Sports drinks during and after training can certainly help, but the best strategy is including more sodium with real foods throughout the day, both experts agree. That means lightly salting your food, throwing a dash of salt in the water you drink, and eating salty soups, Sims offers. One of her favorite summer rehydration tricks: Eat lightly salted watermelon.