Tapering diet – fact or fiction?

At the last track session ahead of the London Marathon at my running club the atmosphere was one of nervous anxiety and a few cases of self-diagnosed ‘mara-noia’ (marathon related paranoia) as over 30 runners were preparing to run 26.2.

I was intrigued to learn about the variety of approaches to nutrition during tapering. As my own marathon (Edinburgh at the end of May) was drawing near, I wanted to know the fact from the fiction behind caffeine withdrawal, eating beetroot and carbohydrate depletion so as to maximize my training ahead of my race. Here are my findings;

Carbohydrate depletion

2016-03-19 13.52.22The classic approach to carb depletion is that you can double your muscle glycogen stores by doing a long run (20 miles) 7 days before your race, then eat a low carb diet for 3 days, followed by a high carb diet for 3 days.  The rationale is that the long run lowers your carb stores, then the 3 days low carb does this further. When the runner then restarts eating carbs it triggers a mechanism in the brain to store more carbohydrate as the body has been starved of it for a period.

Noakes (Lore of Running) argues that the carb depletion means a runner is more adapted to fat burning as opposed to using carbohydrate for fuel. The advantages of fat-adaption according to Noakes are that the runner can continue exercising for longer when muscle glycogen stores are at levels that would terminate exercise in carbohydrate depleted athletes.

However, Pfitzinger and Douglas[1] cite that this approach is old fashioned and actually puts the runner at risk of low immunity (when cutting out the carbs) which isn’t a great place to be in the week before your marathon. They also point out that it would be inadvisable to run long (20 miles) a week before your marathon from a physical recovery point of view – I couldn’t agree more! They argue that eating normally up until 3 days before the marathon, then carb loading 3 days beforehand (eating 70% of your meals of carbs) is safer approach and the one I’ll take on for my event in a few weeks’ time.

To return to Noakes’ point about fat–adaption. It is possible through sustained training in a fasted state (ie run out first thing in the morning, or if you are running doubles (2x a day) then make sure one is fasted) to adapt the body to fat burning without exposing it to the risks associated with carb depletion. My training to this point has involved plenty of early morning tempo and steady runs, therefore I am relatively confident in my body’s level of fat adaption. If you are not already doing some of your runs in a fasted state, I suggest adding this to your training programme.

Caffeine withdrawal Latte

In researching this blog I was surprised to read that until 2005 the World Anti-Doping Agency had caffeine on its banned substances list. Now that tells you something about its potency!  Evidence[2] from ‘run-to-exhaustion’ studies in the lab shows that caffeine can give up to 2% improvement on performance – that could be up to 4 minutes for a marathon.  Caffeine can help the body to spare glycogen, increase calcium in muscles, stimulate the central nervous system (make the pain seem less, lower the perceived exertion level) and allow the body to use fatty acids.

The popular withdrawal method to get maximum benefit from caffeine, like carbs, is to withdraw completely 7 – 10 days before the marathon, then on the day have a coffee as you normally would. The withdrawal can be painful – headaches, dizziness, tiredness, general grumpiness which combined can lead to a less than rosy outlook before the big day – so is it worth it?

Studies by Irwin, et al[3] and Van Soren[4] showed similar improvements in exercise with caffeine in regular consumers vs those who withdraw. Therefore I think I’ll be using coffee on the day, as I have done with other long runs, but not depriving myself of it (and unleash the grumpiness on those around me) in the days before.

Tapering fact or fiction


Across numerous studies[5] consumption of beetroot juice (and other vegetables containing nitrates (dark green leafy veg)) have been found to have positive effects on exercise performance, in terms of improvement in oxygen consumption, time to exhaustion, or overall time to complete the exercise.

For example the University of Exeter[6] has looked at cyclists and runners concluding that in the runners, 500ml beetroot juice every day for a week enabled runners to run 15% longer before experiencing fatigue. Where with the cyclists, those consuming 500ml for 4 days were able to cycle an average of 16 percent longer than those who had drunk the placebo.

Until this year, studies with elite and competitive athletes indicate that nitrate may not be particularly effective[7] because their muscles are already so efficient that it provides no additional benefit. So faster runners concluded that beetroot wasn’t as important. But a recent Dutch study in the journal Nutrients argues that the well trained athletes simply needed a higher dosage[8].  For recreational runners, the right dosage is likely to be 600mg nitrate, where for elites it should be more like 800g. In terms of shots – 2 x 70ml shots (or 500ml of juice) for us mere mortals 6 days before the race,  should have some benefit.

Plus gossip in the running community is that God of running Kipchoge has been a beet juice devotee for the past few years. That should be enough to convince most runners it’s worth trying.

Right I’m off to do my online food shopping, nothing much is changing on the carbs and caffeine front but beet juice will be added to the list.

[1] Advanced Marathoning

[2] Pfitzinger and Douglas. Advanced Marathoning

[3] Irwin C, Desbrow B, Ellis A, O’Keeffe B, Grant G, and Leveritt M. Caffeine withdrawal and high-intensity endurance cycling performance. Journal of Sports Sciences 29: 509-515, 2011

[4] Van Soeren MH, and Graham TE. Effect of caffeine on metabolism, exercise endurance, and catecholamine responses after withdrawal. Journal of Applied Physiology 85: 1493-1501, 1998.

[5] Bond H, Morton L, Braakhuis AJ.

[6] https://www.ncbi.nlm.nih.gov/pubmed/21071588

[7] Eur J Appl Physiol. 2012 Dec;112(12):4127-34 and Scand J Med Sci Sports. 2013 Feb;23(1):e21-31.

[8] https://www.mdpi.com/2072-6643/9/3/314/htm