Athletes must eat large amounts of foods to take in enough calories to fuel their muscles during exercise. A high salt intake in athletes does not cause osteoporosis because they eat so much food that contains calcium and potassium that the amount of salt they take does not cause blood calcium levels to drop, so calcium does not leach out of bones.
As a general rule, taking extra salt causes the body to retain extra fluid, which expands blood volume and increases blood flow to the kidneys to increase loss of calcium in the urine. This lowers blood calcium levels, so calcium has to be taken from bones for replacement. Sodium salt also causes the kidney tubules to lose more calcium. However, potassium blocks the exchange of sodium for calcium in the kidneys and prevents calcium loss. Eating calcium also prevents blood calcium levels from dropping so there is no need for the bones to release extra calcium into the bloodstream (Journal of the American College of Nutrition, June 2006). All fruits, vegetables, whole grains, beans and other seeds are loaded with potassium. Most varied diets contain adequate calcium, but if you decide to take a calcium supplement, be sure you are also getting plenty of vitamin D. Because calcium blocks the conversion of inactive vitamin D to active vitamin D, extra calcium increases your needs for vitamin D.
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