27 May 2014

Nutrition, carbohydrates and mountain ultramarathon running

Summer finally came to Sweden with temperatures in the high 70’s F (25°C) the past week. As there were some heavy afternoon rains last week in between the sunshine it became unusually green and flowery at once and it has been a treat to run even through the city on my way to work with the blossoming Chestnut trees along the river through Uppsala. I also had a good last week with regards to both volume, as I passed 100 km (60 miles), and speed as I had two good hill repeat sessions.

Chestnut trees in blossom along Fyrisån in Uppsala

I long to race now, but I have decided to focus all my training this year on Petite Trotte à Léon (PTL) in August. Not only has the training for PTL gone well, but I and Otto are also good in our planning and preparations also for the logistics of this long race. One thing we still have to plan further is nutrition. In PTL, which is over 300 km and 28,000 D+ vertical meter and consequently will take well over 100 hours, there are only five aid stations/life bases; at Champex after 56 km, at Bourg St Pierre after 100 km, at Morgex after 170 km, at Col du Petit Saint Bernard after 236 km and Col du Joly after 270 km. No aid is allowed in between these stations, but you are allowed to make use of the local infrastructure of refuges and villages to buy your own food and fluid. Planning a good nutrition strategy will be key to finishing this race and it will differ a lot from “normal” mountain ultramarathon races were you can rely on the aid stations to a great extent. Also, the more technically demanding terrain and the strenuous climbs will make the pace much slower than in a normal ultramarathon and thus the energy demands both in terms of total energy expenditure and rate of energy expenditure will be different. Not surprisingly, there is not much written that can guide our planning specifically, but some guidance can be found in the surprisingly vast amount of literature existing about nutrition for ultramarathon running and I will in this post describe some of the recent findings and recommendations in this area.

The first question I asked was how important the gastrointestinal (GI) function is for finishing an ultramarathon race? That it is important for marathon races and other endurance activities have been known anecdotally for a very long time and Bill Rogers once said that “More marathons are won or lost in the porta-toilets than at the dinner table”. My own personal experience is that it is really important, the closest I have come to a do not finish (DNF) in a race was actually due to severe GI problems with vomiting, perhaps due to inexperience with the sport drink they served at the aid stations, and I was lucky the cut-off times were really generous as I walked most of the later parts of the race. I do not think I now ever in the future will be able to even smell Perpetuem from Hammer Nutrition without becoming nauseated. I am not alone in having had this experience and a study found that 90% of ultramarathon runners feel that nutrition has an influence on overall race performance (Kruseman et al “Nutrient intake and performance during a mountain ultramarathon: an observational study” Eur J Appl Physiol 2005; 94: 151-157).

Looking at the realincidence of GI problems at ultramarathon races it is indeed staggeringly high.   Nausea, vomiting, abdominal cramping and diarrhea have been reported in 37-89% of runners participating in 67-161 km long races (Baska et al “Gastrointestinal bleeding during an ultramarathon” Dig Dis Sci 1990; 35: 276-279; Rehrer et al “Physiological changes and gastro-intestinal symptoms as a result of ultra-endurance running” Eur J Appl Physiol 1992; 64: 1-8; Glace et al “Food and fluid intake and disturbances in gastrointestinal and mental function during an ultramarathon” Int J Sport Nutr Exerc Metab 2002; 12: 414-427; Hoffman & Fogard “Factors related to successful completion of a 161-km ultramarathon” Int J Sports Physiol Perform 2011; 6:25-37; Stuempfle et al “Association of gastrointestinal distress in ultramarathoners with race diet” Int J Sport Nutr Exerc Metab 2013; 23: 103-109; Costa et al “Compromised energy and macronutrient Intake of ultra-endurance runners during a multi-stage ultra-marathon conducted in a hot ambient environment”  Int J Sport Sci 2013; 3: 51-62). In a study of the 100 mile (161 km) Western States Endurance Run (WSER), Hoffman and colleagues found GI problems to be the most common reason given for not finishing the race (23%) and the second most common problem impacting race performance among finishers (37%) (Hoffman & Fogard “Factors related to successful completion of a 161-km ultramarathon” Int J Sports Physiol Perform 2011; 6:25-37). That the GI distress can be really severe is evidenced by the several reports of blood in the stool (feces) following endurance running probably due to mucosal erosions and ischemic colitis causing epithelial surface changes in the lower GI tract (reviewed in Prado de Oliveira et al “Gastrointestinal complaints during exercise: Prevalence, etiology, and nutritional recommendations” Sports Med 2014; 44: S79-S85). There might be a number of causes of the GI problems after ultramarathon running including effects on the gut function (splanchnic hypoperfusion, decreased gut motility, decreased absorption and gut permeability), mechanical causes, nutritional causes and adverse effects of non-steroid anti-inflammatory drugs (NSAIDs) often used by athletes. A good recent review of the possible causes was recently published by Prado de Oliveira and colleagues (Prado de Oliveira et al “Gastrointestinal complaints during exercise: Prevalence, etiology, and nutritional recommendations” Sports Med 2014; 44: S79-S85). It is important to mention that nausea, vomiting and GI problems also might be caused by more serious medical conditions like altitude illness (AMS), exercise-associated hyponatremia (EAH) and heat illness.

The next question I asked was if it would be possible to reduce the incidence of GI distress by following a good nutritional strategy? And how should that strategy look like? From fellow runners I have heard opinions as diverse as “in order to avoid GI distress you should only eat fat and nuts during an ultramarathon” and “only carbohydrate gels, water and salt tablets should be taken during a race”. The truth is, as always, completely individual and the one thing all scientific articles in the area seem to agree on recommending is that there is a need for the individual runner to find what works for her or him through empirical testing during training and racing. That said, it is clear that there are some general recommendations to be made based on nutritional studies in ultramarathons (for reviews see Peters “Nutritional aspects in ultra-endurance exercise” Curr Opin Clin Nutr Metab Care 2003; 4: 427-434; Getzin et al “Nutrition update for ultraendurance athlete” Curr Sport Med Rep 2011; 10: 330-337; Knechtle “Nutrition in ultra-endurance racing – aspects of energy balance, fluid balance and exercise-associate hyponatremia” Med Sport 2013; 17: 200-210; Jeukendrup “A step towards personalized sports nutrition: carbohydrate intake during exercise” Sport Med 2014; 44: S25-S33).

Firstly, ultramarathon running almost invariable will induce an energy deficit as it will be difficult to replenish the consumed calories through nutrition. The total energy expenditure during a 100-mile mountain ultramarathon trail race appears to be in the range of 13,000 to 16,000 kcal (Davies & Thompson “Estimated aerobic performance and energy cost of severe exercise of 24 h duration” Ergonomics 1979; 22: 1249-1255; Fallon et al Nutritional and fluid intake in a 100-km ultramarathon. Int J Sport Nutr 1998; 8: 24–35; Cuddy et al “Total energy expenditure, body water turnover, hydration status, and blood composition during the Western States 100” Med Sci Sport Exercise 2009; 41: S336; Dumke et al “Indirect alorimetry during ultradistance running: A case report” J Sport Sci Med 2006; 5: 692-698). There is thus a theoretical need for an exogenous energy intake of 500-800 kcal per hour and as it for most persons only possible to ingest between 200 to 300 kcal/h a massive energy deficit is unavoidable. There are some indications that ultrarunners might increase the ability to take up calories (Kreider “Physiological considerations of ultraendurance performance” Int J Sport Nutr Exerc Metab 1991; 1: 3-27), but no good studies really prove this. It appears thus very important to achieve as high energy intake as possible in order to avoid going completely “empty” and experiencing fatigue and nausea due to hypoglycemia, in particular at a higher running pace. Undernutrition might furthermore contribute severely to mood deterioration during prolonged endurance activities. Also for multiple stage ultramarathons over several days it appears difficult to avoid a negative energy deficit (Clark et al “Nutritional strategies of mountain marathon competitors – an observational study” Int J Sport Nutr Exerc Metab 2005; 15: 160-172; Costa et al “Compromised energy and macronutrient intake of ultra-endurance runners during a multi-stage ultra-marathon conducted in a hot ambient environment” Int J Sport Sci 2013; 3: 51-62; Costa et al “Perturbed energy balance and hydration status in ultra-endurance runners during a 24 h ultra-marathon” Br J Nutr. 2014; 13:1-10.).

Secondly, there appears to be consensus that the majority of the energy during an ultramarathon race should come from carbohydrates. Even though the exercise intensity during an ultramarathon in general is lower than 70% VO2max and most of the fuel utilization is from utilization of stored fat and free fatty acids, there is evidence that exogenous carbohydrates clearly is beneficial as a fast energy source for the muscles to enhance the use of stored glycogen (Jeukendrup et al “Exogenous carbohydrate oxidation during ultraendurance exercise” J Appl Physiol (1985). 2006; 100:1134-41).  However, a small recent study in 15 runners of the 100-mile race Javelina Jundred show that a race diet with higher percentage of fat at a higher fat intake rate gave some protection against GI distress, so clearly not all energy should likely come from carbohydrates (Stuempfle et al “Association of gastrointestinal distress in ultramarathoners with race diet” Int J Sport Nutr Exerc Metab 2013; 23: 103-109). With regards to carbohydrates, most studies show comparable rates of GI distress in runners with high and low carbohydrate percent intake and rate (Glace et al “Food and fluid intake and disturbances in gastrointestinal and mental function during an ultramarathon” Int J Sport Nutr Exerc Metab 2002; 12: 414-427; Pfeiffer et al “The effect of carbohydrate gels on gastrointestinal tolerance during a 16-km run” J Sport Nutr Exerc Metab 2009; 19: 485-503; Stuempfle et al “Association of gastrointestinal distress in ultramarathoners with race diet” Int J Sport Nutr Exerc Metab 2013; 23: 103-109; Mahon et al “Macronutrient consumption prior to, and during, a mountain marathon” Am J Sport Sci 2014; 2: 5-12). The recommendations with regards to the rate of carbohydrate needed during has recently been revised upwards as data indicate that intakes up to 90 g/h might be beneficial, see figure below (International Olympic Committee “IOC consensus statement on Sports Nutrition 2010” J Sport Sci 2011; 29: S3-S4; Jeukendrup “A step towards personalized sports nutrition: carbohydrate intake during exercise” Sport Med 2014; 44: S25-S33). In order to achieve intestinal absorption of this high rate of carbohydrates multiple transportable carbohydrates (i.e. a mixture between glucose and fructose) should be ingested (reviewed in Jeukendrup 2014). There appears to be a dose-response in many studies, in particular during endurance cycling and triathlon events, between high carbohydrate intake and performance, but there are of course no good large controlled studies performed in ultramarathon running. Interestingly, in experiments of running bouts of 2.5 – 3 hour intake of carbohydrates have been shown to reduce the exercise induced inflammatory reaction, in particular rise of the IL-6 and IL-1ra, in plasma (Nehlsen-Cannarella et al “Carbohydrate and the cytokine response to 2.5 h of running” J Appl Physiol 1997; 82: 1662-1667; Nieman et al “Carbohydrate ingestion influences skeletal muscle cytokine mRNA and plasma cytokine levels after a 3-h run” J Appl Physiol 2003; 94: 1917-1925; Miles et al “Carbohydrate influences plasma interleukin-6 but not C-reactive protein or creatine kinase following a 32-km mountain trail race” Int J Sport Nutr Exerc Metab 2006; 16: 36-46).

Carbohydrate intake recommendations (From Jeukendrup 2014)
There are neither any good studies showing particular performance benefits of certain gels, sport drinks and bars containing various mixes of multiple transportable carbohydrates and other nutrients. It is actually quite scary to see some of the claims of sport drink and gel manufacturers with regards to the efficacy of their products. Compared to the standards for pharmaceutical drugs all studies in this area appear to be small studies of very low quality lacking controls, blinding, quite often employing wrong statistical methods and use of poor surrogate endpoints and many studies even lack a primary endpoint and are only descriptive (Henegan et al “Forty years of sports performance research and little insight gained” BMJ 2012; 345:e4797; Thompson et al “How valid is the European Food Safety Authority’s assessment of sports drinks? BMJ 2012; 345: e4753).  Henegan and colleagues state as a conclusion in their survey of the evidence behind (or actually lack thereof) sports drinks that “people should develop their own strategies for carbohydrate intake largely by trial and error”. General consensus appear however to not recommend gels and sport drinks with too concentrated carbohydrate contents and osmolalities over 500 mOsm/L as these appear to be associated with higher GI distress and to balance the intake of carbohydrate gels and drinks with intake of other fluids. I think it also important to stress completely personal features like taste and texture preference of the gel and sport drinks (I know a lot of ultrarunners who have Perpeteum as their favorite race drink while I cannot even smell it without being nauseated as mentioned above). I have found two good overviews of various energy gels at IRunFar (http://www.irunfar.com/2008/12/energy-gel-comparison.html) and Fellrnr (http://fellrnr.com/wiki/Comparison_of_Energy_Gels); they have been helpful for me and appear to still be quite accurate despite being a couple of years old.

Thirdly, there are a number of interesting nutritional strategies were there appear to be growing evidence for benefical effects for shorter running exercises, but were there still is no good data in ultramarathon running. There is much talk about the train low, race high concept with regards to energy and carbohydrates (Hawley & Burke “Carbohydrate availability and training adaptation: effects on cell metabolism” Exerc Sport Sci Rev. 2010; 38: 152-60). I adapt this quite often myself not eating any lunch and have noticed an improvement in running in a low energy state over the past year, but have no study in ultramarathon performance to back up any claims of benefit with this. Another controversial issue is whether to employ carbohydrate loading, in particular with low glycemic index carbohydrates and/or modified starches, or a high fat diet immediately pre-race for an ultramarathon. Again, there are no controlled studies of this in ultramarathon running, although there are small studies suggesting positive effects of both carbohydrate loading and high fat diets for shorter endurance activities (Ormsbee et al “Pre-exercise nutrition: the role of macronutrients, modified starches and supplements on metabolism and endurance performance” Nutrients 2014; 6: 1782-1808). Personally I have always performed best with a short 1-2 day carbohydrate loading regimen before an ultramarathon where I use in particular low glycemic index carbohydrates to fill my stores of glycogen – I know that the scientific rationale for this is almost completely lacking for a race lasting several days, but why not at least start with a completely full tank? Carbohydrate mouth rinse have been shown to be beneficial in shorter races (for reviews see de Ataide e Silva et al “Can carbohydrate mouth rinse improve performance during exercise? A systematic review” Nutrients 2013; 6: 1-10; Jeukendrup “Oral carbohydrate rinse: placebo or beneficial?” Curr Sports Med Rep. 2013; 12: 222-7), but for longer ultramarathons I would be really cautious until it has been shown to at least not be unsafe. Another controversial issue is the ingestion of caffeine and other ergogenic substances in ultramarathons. I will come back to this and discuss this specifically in a later blog post, but personally I noticed the benefit of caffeine in its full extent during TDG last year and it will certainly be an integral part of the strategy for PTL this year. In planning the strategy for such a long race I have also glanced a little on nutritional recommendations for adventure racing as it is so extreme and might not be applicable to “normal” 100-mile mountain ultramarathons (Ranchordas  “Nutrition for adventure racing” Sports Med. 2012; 42: 915-27; Enqvist et al “Energy turnover during 24 hours and 6 days of adventure racing” J Sports Sci 2010; 28: 947-55). The advice common to all ultramarathons over 6-hours appear will anyway be: “Get as much energy into the body as possible without inducing too much GI distress”.

After posting this I got a tip that during Petite Trotte à Léon (PTL) we need to try Léon's blueberry pie in Champex. I already look forward to this; I love blueberry pie, blueberries are indeed beneficial (see my previous blog post), and if we are lucky we will meet the person behind the race, see the video below at http://www.dailymotion.com/video/xt41b0_2012-ultratrailtv-leon-lovey_sport:


2012 ULTRATRAILTV - LEON LOVEY by UltraTrailMontBlanc


  1. Wow. It's clear you put a lot of thought into your race strategy. My one recommendation for PTL would be to buffer your food supply between checkpoints. One of the sources of my downfall in 2013 was not enough calories. I thought we'd reach each life base faster than we did; I thought we'd encounter refuges and stores beyond the official stops listed on the cue sheet; I thought that the aid stations listed in the cues would have the meals they promised. None of these expectations materialized. There were almost no commercial structures on the course between actual towns. Two race-established aid stations had run completely out of food by the time we got there, ransacked by the faster teams who took way more than their share. We were entirely reliant on what we had in our backpacks for segments that took 20+ hours to cover. 2,000 calories doesn't go far in this situation, and my whole team suffered. I was licking clean the packets of peanut butter in my trash bag. So there's my advice. Carry more calories. :)

    BTW, I'm registered for TDG this year and am enjoying your musings on preparations.

    1. Thanks Jill! Great comment - and very important as we had planned to rely very much on the infrastructure so now we have to change our plans I think. Furthermore, your comment really stress the message that it is important to get as much calories as possible during a long race like PTL or TDG :) And, good luck on your preparations for TDG (and Hardrock?)