awesome well let's go to fluid and salt then or sodium even

Yeah, so fluid and sodium, like I said, the first stage for me is to try and collect some data or get some info.

So actually first I'll ask them just subjectively if they think they like about their sweat rate, is it high? And their sweat sodium concentration, do they think it's high? Is it low? And then I'll try and like, hopefully they can get a sweat test or they've had a sweat test to measure their sweat sodium concentration.

And again, with that, I'll see kind of how far off they are.

So Rachel, as an example, is a very salty sweater.

She loses just over 1500 milligrams per litre, of sodium, so really up there, which is tricky when you're going for long durations and you add in heat and things like that.

So when I started working with her and she'd had lots of issues on the hydration side, it was quite obvious early on that her salt was lacking because she was taking on some electrolyte drink mixes, but nowhere near the concentration she was losing.

Someone like Rachel, and maybe not Rachel specifically, but people who run for that long, Cocodona running 50 plus hours, what are they using to get carbs in? Is it only precision fuel and hydration, or would she be eating solid food? And if she is, what is an example of what she would eat to get that carb taken? Because to what David was saying there now, it's a makeup of different stuff in the gut.

When would someone need to repeat the test?

Yeah, so this result is predominantly genetically determined.

So you only really need one test for life.

You don't need, if we tested you tomorrow versus in 10 years' time, you'd be in the same kind of 5 to 10% range, and therefore the recommendation doesn't change.

Your hydration recommendation, the sodium that you aim for, will be the same.

Um, because your losses, that concentration doesn't change.

But like I said, what does change is your sweat rate.

Um, can you speak to that and how, why you would do one or the other?

But yeah, what's the benefits of caffeine? And yeah, kind of what numbers should we be hitting in terms of caffeine intake?

Yeah, so with caffeine, I would say it's not one of the main three levers, is what we call them, which are your carbohydrates, your fluid and your sodium, which you need to perform, keep your body moving, keep your energy levels up.

Caffeine is like a side supplement, which has definitely been proven to boost performance.

The main way it does that, it increases your perceived energy levels, your concentration, your alertness.

A lot of it is quite cognitive, the benefits that you get from taking on caffeine.

But like you said, Sam, it's really... individual some people especially people like i spoke to in my bear today come over and they're like i'm not using any caffeine at all like i totally totally disagree with me and they have nothing on race day whereas you get other people and i think similarly with carbs and everything it's all about having tested that in training to get that benefit and know kind of the levels that you can tolerate.

In terms of like the dosing, there is like a scientifically proven ideal dose, but it's based on body weight actually.

Do you think that there's still a place for faster training at all in endurance training? Do you think that athletes should be trying to take on as much fuel as they can almost as often as they can? Or do you think that there's some days or sessions where maybe their carbohydrate numbers should be a little bit lower or they just get out in the morning and run or ride or swim without having had anything the morning before or maybe the night before? Or should they just do like 30 or 40 grams instead of 90? Just walk me through this kind of mind for you.