How Much Soda Do I Need to Replace During Exercise?

How much sodium do I need to replace during exercise? A really common question that we both get out. There are no guidelines around how much sodium we should have during exercise and so it always seemed odd to me that there was this focus on sodium people talked about it you could test the sodium content in your sweat but yet there was not a single guideline for us. So when I came to do a PhD in 2015 sort of at that stage, I got to actually choose my topic rather than having a project  that I came on to. When I thought well this sodium one is a big unanswered question there's a huge amount of gaps in our knowledge We really don't know how much sodium