Originally Posted by
pdlamb
Minor quibble: Agree a single 40 minute ride electrolytes aren't going to cause the problems OP described. However, if he's riding 40-60 minutes every day in hot weather, and especially on a low salt diet, problems might start to surface after a few weeks.
For quick diagnoses, BF or a TV show is a great place to go. If you want an accurate diagnosis, a medical professional is a better bet.
Electrolyte imbalance is a marketer's diagnosis because they can sell you things like Gatorade. It almost certainly has nothing to do with this, and this is really not something that should be run by the forum for advice. This could be something very real and very serious, and OP needs to talk to a doctor.
Last year, I had tiredness like OP is describing despite being in the best shape of my life. It turned out I had two blood clots growing in my lungs that came fairly close to killing me while working out. I'm not suggesting that OP has that, but this may be a lot more involved than merely drinking or eating something magical.