How To: Sample marathon swim feed schedule (MIMS)

(Apologies to the subscribers who got three unfinished versions of this on Saturday. I was sick for a few days and should have stayed away from the computer, especially after the first mistaken post).

Feed schedules for long swims are often discussed amongst swimmers, but for some reason we are reticent to show them, possibly for fear of criticism.

I can’t claim that any one schedule is definitely the best, only that there are schedules that work and schedules that don’t work and those may be different for different people. Schedules will also be different depending on expected event duration and water and air temperature.

The important questions you must decide are:

  • Do you need hot or cold feeds?
  • What is your feed interval? (Is it the same the whole way through from the start?)
  • Are you planning to take an electrolyte or other break from carb feeds?
  • Do you need painkillers or any medication on the schedule?
  • Do you need or want irregular solid foods or liquids (soup, fruit, tee, coffee, chocolate etc)?
I was asked what I meant by irregular foods. I mean the treats that swimmers often take to reduce salt build up in the mouth, as a comfort food, as something to look forward to in x number of feed’s time, or simply as a break from carbs. Freda Streeter, as you saw in the swim checklist, recommends Milky Ways and Cadbury’s Chocolate Rolls. Finbarr likes Fry’s Turkish Delight, I like tinned peaches, etc.

Here’s my pretty straightforward MIMS feed schedule though, where I was keeping it simple, not even a 2:1 mouthwash.


Let feeds sit in sun for an hour. (This was an instruction to Dee beforehand. In reality it was too warm, and cold feeds, a novelty to me, would have been best for the day)

End of 1st hour     Maxim       700ml

End of 2nd hour    Maxim       700ml

2:30                       Maxim       350ml from here

3:00                       Maxim

3:30                       Maxim

4:00 Dissolved Electrolyte with Ibuprofen, 700 ml.  Mix in advance, let settle

Feed every 20 minutes from here

4:20    Maxim

4:40    Maxim

5.00    Maxim

5:20    Maxim

5:40    Maxim

6:00    Electrolyte dissolved, Mix in advance, let settle

6:20    Maxim

6:40    Maxim with Ibuprofen

7:00    Maxim

7:20    Maxim

7:40    Maxim

8:00    Electrolyte dissolved, Mix in advance, let settle

8:20    Maxim

8:40    Maxim

9:00    Maxim

9:20    Maxim, only if more than 10 mins from end


So the pattern is five Maxim feeds before taking a break and having an electrolyte, with prophylactic painkillers taken twice, just in case, especially since I’d been having shoulder pains for three weeks beforehand. The electrolytes were a larger volume, 750ml and on the third I was only able to take half, despite ongoing dehydration problems, (more details on that in the MIMS swim report). As usual I’d been off caffeine for months beforehand and the Zyn electrolyte was one with added caffeine (20mg), not enough as it turned out as I felt no coffee kick at all, especially at the total amount of caffeine ingested was only about 50mg, about half a cup of standard coffee, which I hadn’t calculated properly beforehand, another lesson. We had actually taken a flask of coffee but with the heat decided against it. A bottle of cold coffee with the electrolyte added would have been the solution, but I didn’t think of this during the swim.

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14 thoughts on “How To: Sample marathon swim feed schedule (MIMS)

  1. Hi Alan, thanks for this, I looked on the Maxim website, they have two types of drinks, a “Carbo Loader” and a “Hypotonic Sports Drink”. Which one are you referring to, when you say “Maxim” in your feeding schedule? Thanks in advance…


      • Thanks Donal. Looks like this stuff is not easy to get outside the US. Do you know if there are any retailers in Australia, or any other means to get it shipped to Australia. Thank you very much for your help and all your fantastic articles, they are great sources of information!


  2. First of all thank you so much for your blog! It has been a lifesaver as I prepare for my Key West swim. I’m curious, how much did you drink once you started feeding every 20 minutes? Thank you!


    • Thanks Alan. Glad it is of assistance. Probably only about 300/ 350ml when feeding that often. You want to balance hydration with feeding too much on carbs and potentially getting sick.


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  4. Great post Donal.
    I did a 25km swim two weeks ago and took in a lot more caffeine, about 20mg per feed. I found this helped with the concentration and limited the “mind wandering”. I should however have included the Ibuprofen, this would have helped me on the last hour or two. Will definitely include the pain killers next time.


  5. Hi Donal,

    my MIMS feeding was quite simple, too simple maybe, but in the end I got there as well (way after you finished the circle):
    – Maxim 300ml every hour during the whole swim: 200ml double strength Maxim topped with 100ml warm (not hot) water;
    – exceptions: 200ml iced tea with 100ml warm water at hour 7; some soft biscuits or chocolate at hours 3, 5, 7;
    – no painkillers, no electrolyte, no other solid food.

    Worked fine with me, although next time in a similar situation I would definitely drink more e.g. 500ml minimum.



    • Thanks Thomas. I had dehydrations problems even taking more than you especially after they held us for so long in the heat before the start and I could have used some cold drinks, something I’ve never had to think about before. Was great to meet you!


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