New guidelines point to an individualised nutrition approach being critical for ultra-endurance participants

Until recently, nutrition and hydration guidelines specific to ultra-endurance exercise of more than four hours were not available, despite the plethora of sports nutrition science evidence published. This type of exercise presents many challenges to its participants, which may be exacerbated by sub-optimal nutrition during these events, often teamed with compromised gastrointestinal function (experienced by 60-96% of participants in ultra-endurance events). Nutrition and hydration play a critical role in fatigue management for ultra-endurance athletes, with thermal stress, dehydration, and depletion of the body’s glycogen stores all playing a contributing role in fatigue development.

Nutrition and hydration guidelines for endurance sports (typically 1 to 4 hours of continuous exercise) do not translate directly to ultra-endurance (more than 4 hours) events. For example, the typical hydration guidelines to avoid more than 2% body mass [1-5] loss do not apply in ultra-endurance activities - and can potentially result in over-hydration, which in some cases can be life-threatening [6]. In fact, body mass losses of well over 2% may be required during some ultra-endurance activities just to maintain a normal level of hydration, due to the loss of weight from the body’s fat and carbohydrate stores over several hours of exercise [6]. This example alone highlights the value that nutrition and hydration guidelines play in designing an individual’s training and competition nutrition and hydration plan for ultra-endurance exercise.

Nutrition and hydration recommendations for ultra-endurance events are now available through two recent publications by leaders in the field; Dr Ricardo Costa from Monash Nutrition, Dr Martin Hoffman from the University of California Davis Medical Centre and Dr Trent Stellingwerff from the Canadian Sport Institute. The guidelines provide both general and competition-specific nutrition recommendations during ultra-endurance exercise [7,8]. They also provide an update on prevention and management strategies for exercise-induced gastrointestinal symptoms during ultra-endurance exercise, which are relatively common.

At a global level, the guidelines emphasise that the needs of ultra-endurance athletes are highly variable. A significant amount of individualised testing, as well as practice in training (and less important races) is necessary to find the optimal solution rather than applying a one-size-fits-all set of guidelines.

When it comes to carbohydrates, the trio recommend that consuming more carbohydrate (within the tolerance limits of the individual athlete) can generally help improve performance. However, in events longer than ten hours that are completed at a relatively low exercise intensity (45-60% VO_2max), it is plausible that a low carbohydrate and high fat diet may improve performance, but there is not yet scientific evidence to confirm this. They also recommend that the safest way to avoid dehydration or over-hydration in ultra-endurance events is to drink according to thirst. Many factors will vary an athlete’s sweat rate during exercise, meaning that a prescribed or pre-meditated drinking strategy is unlikely to correctly match losses. The guidelines also highlight that sodium can be consumed from food and drinks during ultra-endurance exercise, but there is no evidence that athletes should attempt to replace all the sodium lost through sweating.

Whilst there are several strategies to prevent and manage gut issues during exercise, which are relatively common in ultra-endurance events, the causes are complex and interact with each other. Therefore, a thorough assessment of the athlete may be needed to correctly identify the cause and put in place a solution.

Moving forward, Ricardo and his team at the Monash Nutrition Exercise and Nutrition Clinic are currently investigating the role of FODMAPs (starches and sugars that are poorly digested) in preventing gut problems during exercise and the role of sodium intake in the days before endurance exercise on the amount of sodium lost in sweat during the exercise.

More information

These guidelines have been published in Research in Sports Medicine. Click here to access Part 1 which delves into nutrition guidelines. Click here to access Part 2 which explores hydration guidelines.

Dr Ricardo Costa is a researcher at Monash Nutrition and leads the Monash Nutrition & Exercise Clinic, which features the world’s first gut assessment clinic. Ricardo’s research focuses on exercise and the gut, with a specific emphasis on ultra-endurance events.

References

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6. Hoffman MD, Goulet EDB, Maughan RJ. Considerations in the use of body mass change to estimate change in hydration status during a 161-kilometer ultramarathon running competition. Sports Medicine. 2018; 48(2): 243-250.

7. Costa RJS, Hoffman MD, Stellingwerff T. Considerations for ultra-endurance activities: part 1- nutrition. Research in Sports Medicine. 2018. DOI: 10.1080/15438627.2018.1502188