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The question—”is salt bad for athletes?”—is one I’m often asked. When it comes to high sodium intake in the “normal” population the concern is the risk of developing hypertension (high blood pressure) or of it contributing to issues associated with high blood pressure. In healthy people, acute sodium ingestion does not cause sustained hypertension, as athletes and most normal weight active people have lower blood pressure risk due to the nature of the adaptations that occur with aerobic endurance training.
If you sweat on a regular basis and consume limited processed foods (which are notorious for very high sodium content) then the sodium content in normal food should not be an issue. However, this is a prime example of public health research and messaging crossing over into the athletic community with some confused interpretations. We often hear about how bad salt can be for us, but this message does not always ring true for athletes. As a result, I have seen many athletes not consuming enough salt in their normal diets, which can have negative ramifications on performance, especially endurance training (and racing) in warm to hot conditions.
When we talk about “salt” we are talking about sodium and chloride; sodium helps maintain fluid balance and the chloride ion is essential for muscle contraction. During exercise, high sweat rates in athletes result in loss of both fluids and sodium. If fluid replacement is from a low sodium beverage or plain water, you may face possible complications such as hyponatremia, decreased performance, heat cramps, or other heat-related illness. Note, however, that there is significant individual variation in sodium loss during activity (driven by dietary sodium intake, menstrual cycle phase, acclimation, fitness level) with unconditioned athletes and those not acclimated to hot weather typically losing the most sodium in sweat.
Sweat sodium losses do not indicate how much you need per hour of activity, but it does indicate that you need to pay attention to dietary sodium intake as the body is cyclical in storing and releasing sodium. If you know you have a hot, intense session coming up, be a bit freer with the salt shaker at mealtimes or be conscious to consume foods that are naturally higher in sodium to help keep you on track during your session.
Got a question for Dr. Stacy Sims? Submit it here and she might answer it in an upcoming “Ask Stacy” column on Triathlete.com.