We all know that electrolytes are important for performance, not to mention normal bodily functions. There are plenty of electrolyte drinks and whatnot out there, but I prefer to get them through my normal diet. I usually eat pretty well. I don't eat much processed food and try to eat plenty of veggies and whole grains. Even so, I have had trouble getting enough of various electrolytes at times.
The first issue I had was a few years ago with low sodium. It's pretty unusual for an American to have low sodium, but I think the combination of not eating processed foods (that have a lot of sodium), not adding any to what I cooked, and exercising (and hence sweating) a lot, caused my sodium to drop over time. I started having really bad muscle cramps after exercising and even some mild heart arrhythmia. I got a blood test that showed all my electrolytes in the middle of the normal range except sodium which was barely inside the low end. I started adding a little salt to my food and the problems cleared up pretty quickly.
The second issue I had was with calcium. I was just not feeling well and was having a hard time going hard. I felt like I needed to stop and lie down after about 30 seconds of going hard. I didn't know if I was anemic or what, so I went back for a blood test. The only thing that was off was calcium which was barely inside the low end of normal. Calcium is critical for muscle function. I drink a fair amount of milk so I don't know why it was low. It may have been due to the drug tamoxifen I was on to prevent breast cancer recurrence which also caused me significant fatigue. I started taking calcium supplements and started feeling better, although the medication was still taking its toll.
I've recently had an issue that I believe was due to low potassium. (No blood test this time.) Earlier in the summer I had been feeling great and my time trial results were back up to where they were a few years ago. But several weeks ago my body started feeling (especially my legs) heavy and fatigued and like I wasn't recovering well from my work outs. I didn't have any good reason why I was feeling this way. I tried giving myself plenty of rest and recovery, but the next hard workout set me back again. I started googling "heavy legs" and several running websites suggested it could be due to low potassium. I can't eat things like bananas too frequently because I start having allergic reactions to them so I needed to find a source of potassium I could eat daily. I looked into supplements but they only contained 3% of the RDA and that didn't seem worth the expense and bother. Then I remembered that salt substitutes are made of potassium chloride and thought that I could use that. So I started adding 1/8 tsp (10% RDA) to my oatmeal every day and lo and behold, started feeling great again. Now I can crank out my hard workouts and bounce back like I used to.
The thing that surprises me most is that I could experience such symptoms when the electrolytes weren't that far off of normal and how small the additions to diet it takes to feel better. Food for thought!