Supplements – some advice

After I posted the other day about trying supplements for the first time I got some really good advice in the comments. So good in fact, that I’m going to repeat it here as a separate post.

First, from Mike:

Given the length of swim, I’d think you should understand your carbohydrate burn rate and sweat rate. You definitely need to be putting stuff back in, and timing it right, in the right amounts, will make a huge difference to how you feel & finish when doing anything longer than 2hrs. Shorter than 2hrs, your body uses what’s in your bloodstream/muscles anyway, so eating is not really of benefit (although plenty of people eat after even 30 minutes, or are sucking on sweet carbo drinks from the go – more a placebo effect than anything I imagine).

You should weigh yourself dry using some accurate scales before and after a 1hr session at your race pace, deduct any drinks you had (try not to do a wee) and that should give you your sweat rate. I know mine is anywhere up to 800ml an hr in 18deg on the bike. If you drop more than 2% accepted wisdom is you start to suffer. Some people sweat loads more than others, and some have a hard time drinking enough to keep up. You won’t know until you actually run the tests.

What you must do is ensure you keep a balance in your electrolytes, otherwise you risk all sorts of bad stuff – un-coordination, nausea, vomiting etc etc. It’s not critical that your drink be an energy one – I use a non-energy electrolyte-only tablet called NUUN – they work well for me purely as an electrolyte replacement. They also get used in some hospitals for rehydrating people.

Food is far more about personal preference IMHO – and £2-a-go bars or squeezies are not the answer. A banana has as much energy as a gel, has potassium too, and comes in an eco-friendly wrapper :-) . Peanut butter sandwiches, fig rolls, malt loaf, Haribo…the list goes on of food people swear by. What you feel like eating at the 1hr mark is probably going to be very different to nearing the end. After an 8hr adventure race I’m lucky to be able to eat anything – I physically find it hard to consume enough calories to keep going at the same pace. This is something I need to work on – more cake nurse! ;-)

Great advice Mike, thanks. I like the idea of weighing myself to be more scientific about it. In my case the results are likely to be “too much” and then after the session “still too much” but you’re right that it will give me a good benchmark.

As for food, I agree completely about the bars and gels – swimming Windermere last year I had jam sandwiches and flapjack.

I also got some great advice from Sean:

What you’re talking about here is a nutritional strategy. In that sense these aren’t ‘supplements’ they are primary nutritional sources for your endurance event.

As Mike says, it could be a banana or a gel, but if you’re doing something for 7+ hours you’ll need nutrition, lots of nutrition, otherwise you’re going to ‘bonk’.

Also, as Mike points out, you need to understand your burn rate. I’m guessing yours is somewhere in the region of >1,000 calories an hour while swimming. You’ll need to define that more accurately — get yourself a Garmin Swim (

The average person can process about 400 calories an hour while exercising (you might be >500 or <300, you need to work that out too). So you need to calculate your total burn for your event and then see how much additional nutrition you will need per hour to complete while at the same time understanding that you cannot consume too much without risking gastric distress.

This will affect how you train for the event.

However, part of your nutrition strategy will involve you begin feeding within 30 minutes and then at set intervals throughout your event you continue feeding.

You don’t have to ‘just believe’ that supplements will work. There’s a whole body of scientific research that supports the fact that they do. What you have to do is work out how much you burn and how much you can replace.

As for the “just believe” comment, Sean is referring to what I said in the original post and maybe I should have made myself clearer. What I meant was that I couldn’t scientifically prove that they had helped my performance on that occasion as I couldn’t compare it to the same session without the drink. At my level there are so many other factors (how work was, what I did at the weekend, how much I alcohol I drank yesterday, when I last went to the gym etc etc) that I will never have a like for like test of supplements. I do believe that a better nutritional strategy (as Sean calls it) will improve my training, but I’ll never be able to prove it.

Anyway, lots of food for thought on food for training.


1 Comment

Filed under Motivation, Swimming

One response to “Supplements – some advice

  1. “I do believe that a better nutritional strategy (as Sean calls it) will improve my training, but I’ll never be able to prove it.”

    Actually, you can: do a 4hr swim / run / cycle without eating/drinking anything.

    After they drag your body from the water / roadside and revive you, wait a few weeks and then repeat, but this time consuming measured amounts of carbs/fats/proteins and electrolytes.

    There should be less emergency first-aid required 😉

    …and to be clear: I’m not saying don’t eat in the first two hours – just that if 2hrs was all you were going to do, it’s not a big deal. But if you are going for longer you will definitely notice not fueling properly in the first 2. When I’m doing day-long stuff I eat from the 30-60min mark, but not much, and slow-release stuff, that the tum will take a few hours to process so it’s kicking in at the 2-3hr mark. Keeping yourself on a steady plateau of blood sugar is the key – going from knackered to superman and back every hour based on massive gel-fuelled swings makes for a miserable event and a crap finish time. For this reason I hardly ever use gels, preferring regular small amounts of real food. Gels are there as a backup when you get your normal plan wrong due to weather/race conditions/developing illness/being a numpty.

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