It’s pretty evident that multi-day running events are increasing in popularity. With this heightened physiological and psychological demand, there’s a need to identify the runners ‘fatigue factors’ and therefore programme strategies to overcome them in order to successfully complete these challenges.
The fatigue factors attributed to a decline in performance are; dehydration, hyperthermia, carbohydrate depletion, central fatigue and hypoglycaemia.
A 2017 case study by McManus et al provides a road map and insight on how this can be achieved….The case in question was a 38 year old female wanting to run 26 marathons in 26 consecutive days. For easiness, let’s call here Helen.
Over the twenty-six day period, Helen completed the same 1 mile course (Edinburgh ‘Royal Mile’), which you’d agree is a large psychological challenge in itself, running the same course 681 times…lol.
The average marathon time was 6h 21 min, where she consumed a total calorie intake of 99,570kcal and drank 112,9L of fluid.
Helen started the marathon at 60.5kg, but gained 1.1kg, despite losing ~4.6kg of body fat. This was potentially due to hypervolemia (fluid retention) as a result of the increased physiological demand. Therefore we can’t always rely upon the scale weight to determine whether you’re eating enough to maximise performance and recovery.
Since Helen dropped body fat, she would have been in an energy deficit despite eating 3,829kcal on average, which is ~64kcal/kg. Helen also worked off the principle of #NoCarbohydrateDeficienciesHere as her daily carb intake averaged almost 10g/kg and 600g (range = 439-712g/day).
Therefore confirming that you can drop body fat with very high carb diets!
Knowing that Helen dropped body fat and was in an energy deficit, she would have experienced compromises in fuelling and recovery, which negatively compounded her performance as running times declined towards the latter phase of the challenge.
Although Helen consumed ~39g of carbs/hour during the run (range = 20.7g-65g), it didn’t quite hit the evidence based recommendations of 90g/hour. That being said, running times were on the slower side and ‘optimal’ would have been approx. 60g/hour to support running performances of that intensity and duration.
There are a few conclusions to be drawn from this case study:
1) Energy deficits compromise performance and therefore more consistency would have been needed in total daily and intra-run carb intakes to overcome a decline in running speeds.
2) The scales can be misleading as an indicator of full replenishment and recovery (i.e. energy balance).
3) She probably wouldn’t have been able to complete this challenge without an evidence based approach. Even though it wasn’t executed perfectly, it’s far better than guessing what to do. This is why nutrition programmes and education are super important for challenges such as these. I.e. eating intuitively probably isn’t the best idea unless you’re a very experienced multi-day marathon runner.
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