Most doctors recommend low salt diets because of the evidence that taking in too much salt can cause high blood pressure, a major risk factor for heart attacks and strokes. However, this may not be good advice for dedicated exercisers. If you exercise heavily and restrict salt, you will not replace the salt you lose through sweating, which can cause high blood pressure as well as fatigue, cramps and muscle pain. When the body is low in salt, the adrenal glands produce large amounts of aldosterone and the kidneys produce renin, which constricts arteries and can raise blood pressure.
Researchers at Albert Einstein College of Medicine showed that people on low-salt diets are actually more likely to suffer heart attacks than those on high salt diets (Journal of General Internal Medicine, June 2008). They analyzed data from the Third National Health and Nutrition Examination Survey (NHANES III) of American adults. Dr. Hillel W. Cohen, lead author of the study, stated, "Our findings suggest that for the general adult population, higher sodium is very unlikely to be independently associated with higher risk of death from heart attacks."
Many years ago, when I was competing in marathon races, I decided to try a low-salt diet. I was surprised to find that my blood pressure rose from a normal 120/ 80 to as high as 160/80, and I suffered severe fatigue and frequent injuries. When I added salt back into my diet, my blood pressure went down to normal and I was able to train and compete again. This is why I recommend a relatively high-salt diet for exercisers. If you decide to increase your intake of salt, get a blood pressure cuff and check yourself for a month. If your blood pressure goes above 120/80, you may have added too much salt. Also, if you stop exercising because of an injury or for any other reason, be sure to cut out the extra salt to keep your blood pressure under control. More