The Nutritional Demands of Ultra-Endurance Running
(a) London Bridge Hospital Dietetic Department; (b) Coventry University Ultra-Endurance Nutritional Support & Research Team; (c) Department of Health Professions, Coventry University.
Demands of the Sport
Ultra-endurance running is classified as prolonged running lasting more than 4 hours in duration and encompasses the majority of one-stage and multi-stage ultra-endurance running events commonly exceeding 100 miles in distance. Multi-Stage Ultra Marathon (MSUM) events (e.g. Marathon Des Sables, The Gobi Challenge, Al Andalus Ultra-Trail, Trans-Alpine, Trans-Rockies, The Jungle Ultra, Atacama Crossing, and The Yukon Ultra; www.racingtheplanet.com) have increased in popularity over the last decade, and are predicted for future growth amongst endurance sports enthusiasts.
MSUM are characteristically unique as they present physiological, psychological, and real-life practical challenges. Not only are ultra-runners required to perform loaded (e.g. pack weight normally ranging from 5 to 15kg) prolonged strenuous exercise and sleep rough (e.g. outdoors, tents, sports halls) during competition (commonly for 5 to 8 days); but are also required to carry, prepare, and consume sufficient foods and beverages to maintain optimal running performance on consecutive days of competition. The added environmental stressors of either competing in hot (>30°C) or cold (<0°C) ambient conditions on a semi-self sufficient or fully self sufficient basis further highlights the importance of long-term preparation and appropriate environmental acclimatisation prior to competition.
Physiological Demands of Ultra-Endurance
Running In all events, there will be elite athletes; however the majority of ultra-runners participate with the sole aim of completing each stage. For all ultra-runners, the critical determinant of success is their ability to sustain a constant high rate of energy output for a prolonged period of time, whilst preventing illness/injury (e.g. muscle soreness, blisters, sunburn, upper respiratory and/or gastrointestinal symptoms). During such prolonged efforts, nutrition and hydration increasingly impacts on running performance, to the extent that these aspects can differentiate between those who finish and those who do not.
Carbohydrate is the prime fuel needed to sustain high rates of prolonged exercise. However, carbohydrate stores in the muscle and liver are limited. With specific ultra-endurance training the body will adapt to spare muscle carbohydrate reserves and favour using fat energy reserves as a prime fuel source during running. Additionally, the sheer physiological and mechanical stress of ultra-endurance training will improve the body’s ability cope with the stress impact of running and therefore, reduce the risk of structural injuries during competition. Appropriate rest and nutrition between sessions will support
physiological adaptations and reduce the severity of any injury/illness that does occur.
Nutrition and Performance
Key Nutritional Issues
Energy & Macronutrient Requirements
Nutritional recommendations for ultra-runners acknowledge the importance of foods and fluids in sustaining running performance and minimising fatigue during both training and competition. Increasing race enjoyment must also be considered when preparing and competing in MSUM. For consecutive days of ultra-running, the dietary aims are to achieve energy balance, provide adequate carbohydrate and fluid to cater for losses incurred by the running load, supply sufficient protein for repair and healing, and
include a variety of foods/beverages to supply adequate healthy fats and micronutrients.
As training volume intensifies, daily energy requirements are raised. There is often an inverse relationship between the time available and motivation to prepare and consume adequate food/beverages to meet energy needs for effective performance and recovery, thus exposing ultra-runners to potential energy and nutritional imbalances. Along ultra-endurance training programmes, a simple and generally reliable way to identify whether an ultra-runner is consuming sufficient energy to meet training demands is to record
body mass on a weekly basis. Small fluctuations in body mass (BM) should be expected, but a consistent, unexplained and unintentional BM loss represents an energy deficit and needs to be addressed (e.g. modify training programmes, revisit and readjust dietary intake adequacy).
During actual competition, numerous interlinking factors may negatively affect energy intake such as appetite suppression, food rationing, lack of food preparation time and facilities, and change in food/fluid preference along the course of the competition. These are often only acute imbalances that will not generally lead to significant on-going weight loss; but may impact temporarily on performance. Therefore, dietary strategies need to be put in place to cater for achieving energy provisions during competition.
Carbohydrate represents the main energy source for brain and body. Carbohydrate
requirements for optimal ultra-running performance vary depending on the running intensity, running duration, and environmental conditions; as well as individual fitness level, gender, body composition goals, and food/fluid ingestion tolerances. Due to limited storage capacity in muscles, carbohydrate can only sustain running exercise without adversely affecting performance for 60 to 90 minutes. Therefore, during running exercise lasting >1 hour, additional carbohydrate should be supplied. Suboptimal carbohydrate intake during periods of intensified ultra-endurance training can lead to reductions in muscle mass, bone density losses, early fatigue, and increased illness/infection rates; overall an inadequate and/or more prolonged recovery and long-term poor ultra-running performance.
If an ultra-runner is able to meet their training and competition energy requirements using a variety of food groups, they are also likely to be meeting the recommended daily protein values for endurance sports. Therefore, protein or amino acid supplements are not usually required by ultra-runners. However, the timing and type of protein intake is potentially important in influencing the quality of recovery and training adaptations. Firstly, the inclusion of high biological value protein (protein that contains a good reservoir of all essential amino acids; e.g. lean meats, oily fish, eggs, low fat dairy, soya,
and quorn) in meals, to accompany carbohydrate rich food source, provides a consistent dose of nitrogen required for prolonged body repair, healing, and growth. Secondly, immediately after ultra-running the ingestion of high biological protein in adjunct with carbohydrate aids short term repair, healing, and growth, all contributing towards training adaptations. There is also some evidence to suggest consuming small amounts of milk proteins (whey or casein), in adjunct with carbohydrate, before and during ultrarunning
may potentially promote a better nitrogen profile during consecutive days of prolonged strenuous running.
Fat represents the body’s main energy reserve and is increasingly mobilised at lower exercise intensities to help spare muscle carbohydrate stores. Although dietary recommendations for fat intake are based on an individual’s body composition and sporting objectives, ultra-runners in general should modify their fat profile by focusing predominately on the intake of ‘good’ fat types which will help reduce inflammatory and oxidative stress (e.g. monounsaturated and omega 3 polyunsaturated fats). In practical terms, this means using low fat dairy products, using olive-oil based spreads and oils in cooking and food preparation, and eating more oily fish (salmon, mackerel, herring, trout, sardines, kippers), selecting lean cuts of meat whilst also avoiding high fat snacks (crisps, biscuits, chocolate, cakes), and avoiding trans-fats particularly in freeze-dried meals commonly consumed during competition.
Ultra-runners should include a variety of all food groups in their daily dietary intake, and aim for ≥5 servings of mixed fruit and vegetables per day, to achieve their recommended intake for vitamins, minerals and antioxidants. Micronutrient supplements are not required during training if ultrarunners are consuming a varied diet to meet energy demands, as micronutrient intake is likely to exceed the Reference Nutrient Intake (RNI) values. Conversely, during ultra-endurance running competition, due to limited food variability along the course of MSUM events, meeting daily micronutrient needs may
pose a challenge. If an ultra-runner feels more secure taking a supplement to ensure requirements are being met, a complete multi-vitamin/mineral supplement (x1 per day that provides no more than 100% RNI) is a safe dosage to recommend and can act as an insurance policy during period of acute deficits. Large doses of vitamins/minerals do not enhance performance in healthy ultra-runners and mega-doses may promote toxic side-effects; therefore vitamins/minerals mega-doses should be discouraged.
“Protein, vitamin and mineral supplements are not required if an ultra-runner is consuming a varied diet to meet their ultra-endurance energy demands”
The development of hydration strategies has traditionally focused on preventing significant degrees of dehydration (exercise-induced body mass losses of ≥2%) to avoid decrements in endurance performance. Of more recent concern, are the observed high plain water consumptions and low sodium intakes among ultra-runners, placing them at higher risk of low plasma sodium levels (over-hydration and hyponatraemia). Therefore, it is advised that ultra-runners avoid over-hydrating on plain water; instead “drink to thirst” using carbohydrate rich fluids (e.g. sports drinks, fruit juices, or soft drinks), which contain additional electrolytes (especially sodium). In some self-sufficient MSUM events, ultra-runners must ration water supply (e.g. race quota of 9 to 12 L/day) along the course, promoting a potential barrier to optimising fluid provisions. Practically, this involves rehearsing how to carry appropriate fluids, how to add carbohydrate and sodium sources on the move, and the overall management and budgeting of water between check-points.
Pre-Race/Stage Nutrition & Hydration
Preparation of foods to be consumed during a MSUM is a key determinant of success. Thorough organisation will ensure that a compromise is reached between achieving a light pack-weight and carrying sufficient fuel for each stage; taking into account that race organisers often enforce a 2400kcal/day minimum energy provisions on participants. Well tolerated and familiar foods work best when competing in MSUM.
In the days leading up to the first stage of the MSUM event (e.g. at least three days prior), increasing total daily carbohydrate intake (through carbohydrate rich foods and fluids) while reducing training load leads to substantial increases of muscle carbohydrate stores, thereby promoting an excellent starting point. With little time available in the morning before the on-set of each stage, only tolerable, high carbohydrate, low fat, low fibre foods (e.g. white bread jam sandwiches, fruit tarts, cereal bars, easy to prepare sugary cereals) and fluids (e.g. milks, fruit juices, soft drinks, sports drinks) should be consumed to facilitate rapid gastric emptying and nutrient absorption. It’s often unfeasible to eat 3-4 hours pre-stage, as this would reduce ultra-runners valuable sleep time. Early morning starts realistically allow 1-2 hours for breakfast consumption; the aim of which should be to primarily top-up liver carbohydrate stores (at least 100g carbohydrate ingestion). Some ultra-runners find that including a carbohydrate-rich drink (e.g. milkshakes, fruit juices, or sports drinks) and/or a light snack (e.g. handful of dried fruit, carbohydrate gels, fruit shoot purees, and/or an energy bar) in the 60-90 minutes before starting is better tolerated and helps prevent decreases in blood sugar levels during the early section of the running stage.
With regards to fluid, the main aim is to begin running in a fully hydrated state. Urine colour (2nd urine of the day) can give a quick indication of hydration status; although this measure becomes less accurate if large volumes of caffeine, alcohol, or plain water are consumed. Ensuring urine is clear/pale prior to each MSUM stage start, by frequently drinking moderate amounts of carbohydrate rich fluids which are well tolerated, as previously described, will help achieve optimal hydration and provide a valuable source of
carbohydrate energy. Ideally, fluid intake strategies prior to each stage of a MSUM should be tailored to each individual ultra-runner, based on their fluid losses induced by the previous running load and environmental conditions.
During Running Nutrition & Hydration
The additional intake of carbohydrate is warranted during any prolonged exercise (>1 hour) to help prevent significant decreases in blood sugar levels. It is recommended that ultra-runners consume at least 30-60g carbohydrate per hour of running to extend endurance capacity. Delivery in a beverage form (e.g. sports drinks, fruit juice, or soft drink) is the most effective in providing fluids, carbohydrates, and electrolytes (especially sodium). However, individual tolerances will dictate which drinks, gels or carbohydrate rich solid foods are chosen. The actual form of carbohydrate ingestion is generally irrelevant in MSUM; what matters is the total quantity of carbohydrate consumed per hour.
Examples of foods/fluids that contain 30-60g CHO:
- 500ml fruit juice or soft drink.
- 500ml sports drink (e.g. Aquarius, Isostar, HighFive, Lucozade sport, Powerade, and/or Gatorade).
- Energy or sports nutrition bar (make sure they are low in fats and fibre).
- 2 handfuls of sweets or dried fruit (e.g. jelly beans, jelly babies, wine gums, raisins, sultanas, or any dried fruit of your choice).
- 4 to 6 jaffa cakes.
- Cereal bar (e.g. Rice Krispies, Frosties, Cheerios).
- 2 carbohydrate gels or fruit shoot purees.
If solid foods are ingested during running, it is important to accompany this food ingestion with water to dilute its concentrated nutritional content, minimising potential gastrointestinal distress. Additionally, sports drink already contain a substantial sodium source; however if using other carbohydrate rich fluids (e.g. fruit juice or soft drink) a pinch of salt (or other sodium forms; e.g. Nuun, Elete, and/or Dioralyte) should be added to these fluids (e.g. ~400mg of sodium per 500ml of fluid). Cooler fluids are likely to increase palatability, and therefore encourage voluntary fluid intake. Fizzy/carbonated drinks are a more concentrated source of carbohydrate than sports drinks and can be well tolerated by ultra-runners, but in some runners may induce bloating/ gastrointestinal discomfort, subsequently decreasing voluntary food and fluid intake. Practising competition dietary strategy during training is highly recommended and fundamental to see what works and is well tolerated, avoiding gastrointestinal upsets during MSUM competition.
Nutrition & Hydration Recovery Post-Stage
Immediately post-stage, the goal is to restore lost muscle carbohydrates stores, body fluids and electrolytes (ideally within the first 30 minutes of finishing). It is highly recommended that ultra-runners consume a well tolerated carbohydrate-rich snack before appetite suppression sets in. Delaying carbohydrate intake by 2 hours reduces muscle carbohydrate store replenishment by up to 50%, which will largely impact on recovery and running performance in the next stage, particularly important when competing on consecutive days. Additionally, selecting carbohydrate-rich foods and drinks that also contain protein and electrolytes, not only increases palatability and voluntary consumption, but provides
the body with a significant protein dose to aid repair and healing, and sodium dose to optimise the rehydration process.
Using low-fat milky drinks, as a nutrient dense recovery beverage, provides a cheaper and often more palatable alternative to commercial recovery drinks, and when enriched with additional skimmed milk powder can help decrease pack-weight. Homemade milkshakes made up with skimmed milk, skimmed milk powder, and some chocolate or strawberry flavouring provides the ideal recovery beverage.
Examples of foods which combine adequate amounts of carbohydrate and protein (plus contain some electrolytes):
- Recovery drink (homemade or commercial (e.g. Powerbar Recovery, Rego Recovery, and/or HighFive Recovery))
- 500ml low fat milkshake or yogurt.
- Large bowl of breakfast cereal with enriched skimmed milk (enriched with skimmed milk powder).
- 1 can of low fat rice pudding and a pepperoni stick.
- 500ml low fat readymade custard.
- Spaghetti/beans/cottage cheese on 3-4 slices of toast or toast with peanut butter.
- 500ml of soft drink with a sandwich, pitta bread, or bagel filled with tuna, ham, or chicken.
Additionally, the time between subsequent stages will also shape rehydration strategies. Standard meals and drinks should supply adequate fluids and electrolytes. However, in those ultra-runners with particularly high body sweat rates, consuming foods and drinks with a substantial sodium source (e.g. bakes crisps, dried meats, tuna in brine, salted nuts, and/or instant cup soups) may be warranted to replace excess losses.
Challenges & Barriers
Anecdotal evidence suggests that ultra-runners may find it difficult to follow the above recommendations during MSUM competition for a variety of reasons. These include lack of nutritional education, ultraendurance cultural trends, development of unintentional symptoms (e.g. appetite suppression, nausea, vomiting, diarrhoea) during competition and/or possibly due to real-life factors (cooking/food preparation facilities, time, equipment and/or location) which will limit total food and beverage intake during consecutive days of competition. If these factors are of concern and are issues for an ultra-runner, then strategies to overcome challenges and barriers need to be put in place prior to MSUM competition.
Key Nutritional Take-Home Messages
- Consume adequate energy to meet energy requirements, fuel exercise, and delay fatigue.
- Ensure a varied, balanced diet made up of all food groups, containing healthy fats, lean protein and provide sufficient micronutrients to meet RNI.
- Go for high carbohydrate meals and snacks in the days leading up to the MSUM competition .
- Pre-stage: If possible, consume a carbohydrate-rich, low fat, low fibre meal/drink 1-3 hours prior to the stage start.
- Start the stage with a clear/light urine colour.
- During stage: Aim for high carbohydrate foods/beverages which are individually tolerable and trialled extensively in training.
- Drink to thirst during running using a sports drink (6-8% carbohydrate). If using fruit juice or soft drink, add a pinch of salt for every 500ml.
- Post-stage: Consume carbohydrate containing foods and beverages, with some protein and electrolytes, such as a milk based recovery drink within the first 30 minutes after finishing the stage.
- Develop individually tolerated dietary strategies that aim to replenish carbohydrate stores on consecutive days of prolonged strenuous running.
This fact sheet is the view of the authors and is for information purposes only
For more individualised dietary advice for ultra-endurance running training and/or competing, it is recommended you contact a registered Sports & Exercise Dietitian (www.senr.org.uk)
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