How Much Salt Do You Need to Replace During Exercise?

The body weight of the athlete made no difference in percentage terms for how much sodium you needed to replace. The higher that got towards 100% the more sodium you actually needed to replace and interestingly it wasn't until you replaced more than about 70 to 80% of your fluid losses that you really have a requirement to replace any sodium during exercise. It seems to be that around that 70 to 80%. mark is kind of a tipping point where you go from the blood sodium concentration going up during exercise to where you're drinking enough fluid enough water.