Sweat can contain anywhere between 818 and 1,248 milligrams of sodium per liter, according to Rice University. And, it's not uncommon for athletes to lose half to a full liter of sweat per hour of training in the summer heat. This means most athletes lose 409 to 1,248 milligrams of sodium per hour. For any athlete trying to progress in a sport, these are important numbers.
Although those with high-sodium losses won't likely be able to consume and replenish every milligram of sodium lost while training, getting at least 400 to 700 milligrams per hour is a good goal. Especially during the summer and when exercising for more than 60 minutes, this range of sodium intake can improve performance and reduce risk of hyponatremia (low sodium).
Hyponatremia symptoms include headache, confusion, nausea and vomiting, loss of energy, fatigue, irritability, muscle weakness, cramps and more. Sodium is important for fluid absorption in the intestines, cellular function, brain function and muscle function.
Sodium-loss rates depend on variables including sex, size, intensity and environment. We do not all sweat at the same rate, nor does our sweat have the same amount of sodium in it liter-to-liter.
Typically, athletes who sweat a lot are encrusted in white salt and could wring out their jerseys after an intense ride or run. They may experience low-sodium symptoms frequently while training.
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In addition to using sports drinks with at least 100 milligrams sodium per 8 ounces, fuel options with sodium and electrolyte supplements or pills, you can try starting each workout with a sodium pre-load.
What Sodium Pre-Loading DoesWhen you pre-load with sodium, you do two things proactively:
1) You reduce your risk of being depleted of sodium, especially during the first 60 to 90 minutes of training. Studies show that sodium pre-loading adequately supplies the body with enough sodium to maintain balance, even in extremely hot conditions and intense training. However, the pre-load in the studies was very high in sodium, at more than a teaspoon of salt (2,400 milligrams sodium) sipped in intervals beginning 2 hours beforehand. During the test, the cyclists did not use additional sodium on the bike, nor did they ride for longer than 90 minutes.
Consume 600 milligrams of sodium (1/4 teaspoon of salt) plus additional electrolytes during training. This will help you maintain balance in hot conditions, even for longer than 90 minutes.
2) You increase blood volume. Sodium has what's called an oncotic pressure, or a pressure that draws fluid to it. Because a small amount of extra fluid in the blood stream is useful in the body when exercising, it's beneficial to start out with more.
This is different than retaining too much fluid and swelling, which often occurs when you eat a meal that's too high in sodium or take a high-sodium supplement while training. In this type of fluid retention, the fluids move into non-plasma, non-cellular space between tissues (known as third-spacing) and cause swelling.