Real-Time Observations of Food and Fluid Timing During a 120 km Ultramarathon.

Floris C Wardenaar,Daan Hoogervorst,Coen C W G Bongers,Joline J Versteegen,Karin J Lambrechtse,Nancy Van Der Burg

doi:10.3389/fnut.2018.00032

Abstract

The aim of the present case study was to use real-time observations to investigate ultramarathon runners' timing of food and fluid intake per 15 km and per hour, and total bodyweight loss due to dehydration. The study included 5 male ultramarathon runners observed during a 120 km race. The research team members followed on a bicycle and continuously observed their dietary intake using action cameras. Hourly carbohydrate intake ranged between 22.1 and 62.6 g/h, and fluid intake varied between 260 and 603 mL/h. These numbers remained relatively stable over the course of the ultra-endurance marathon. Runners consumed food and fluid on average 3–6 times per 15 km. Runners achieved a higher total carbohydrate consumption in the second half of the race (p = 0.043), but no higher fluid intake (p = 0.08). Energy gels contributed the most to the total average carbohydrate intake (40.2 ± 25.7%). Post-race weight was 3.6 ± 2.3% (range 0.3–5.7%) lower than pre-race weight, revealing a non-significant (p = 0.08) but practical relevant difference. In conclusion, runners were able to maintain a constant timing of food and fluid intake during competition but adjusted their food choices in the second half of the race. The large variation in fluid and carbohydrate intake indicate that recommendations need to be individualized to further optimize personal intakes.

Highlights

An ultramarathon is any footrace longer than the traditional marathon length of 42.195 km
Previous studies investigating nutrient intake in ultra-endurance events reported a wide range of carbohydrate intake (23–71 g/h), which was often lower than the recommended intake of [60–90] g carbohydrates per hour (8–19)
Two of the runners said to use a carbohydrate rich diet in the days before the race, one of the runners said to focus mainly on extra fluid intake and five runners did not change their dietary intake in preparation for the race day

Summary

Introduction

An ultramarathon is any footrace longer than the traditional marathon length of 42.195 km. Ultra-endurance performance is highly dependent on the intake of carbohydrates during the race. In addition to muscle glycogen stores, up to [60–90] g of exogenous carbohydrates per hour are advised to maintain relatively high exercise intensity levels during ultra-endurance performance (1–5). Carbohydrate oxidation in recreational well-trained, non-fat adapted runners has shown to be the dominant energy source (≥70% of the total energy expenditure) (6, 7). Previous studies investigating nutrient intake in ultra-endurance events reported a wide range of carbohydrate intake (23–71 g/h), which was often lower than the recommended intake of [60–90] g carbohydrates per hour (8–19). Besides the need to consume sufficient carbohydrates, ultramarathon runners need to prevent excessive dehydration (>2% body weight loss from water deficit) in prolonged exercise

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Conclusion