Hi, I am a 65 year old female. Very fit and on no medication. I play tennis three to five times a week on hard courts. Lately, I have been experiencing muscle tingling and cramping after a couple hours of play. I have had two severe episodes where I was dehydrated and needed IV fluids. The last time was after a very long , intense match in the heat of the summer with very high humidity. I had done all of the proper things (or so I thought) as far as hydration both prior to and during the match. However, the last two times this has happened, it has not been hot or humid. I continue to take in plenty of fluids and have added a hydration mix to my water. Any ideas????? Thank you Linda Wittendorfer