When the sodium level in the blood is excessively low, a condition known as hyponatremia can develop. One loses sodium while they exercise, and the more sodium is lost, the more sodium replacement is required to lower the risk of hyponatremia.
Adults who routinely exercise tend to have hyponatremia, which if unchecked can become extremely severe. Headaches, weariness, nausea, and confusion are among the warning indications. The good news is that it can be quickly resolved by taking salt before exercising.