Dietary Observations of Ultra-Endurance Runners in Preparation for and During a Continuous 24-h Event

Emma J Kinrade; Stuart D R Galloway

doi:10.3389/fphys.2021.765888

Dietary Observations of Ultra-Endurance Runners in Preparation for and During a Continuous 24-h Event

Front Physiol. 2021 Nov 24:12:765888. doi: 10.3389/fphys.2021.765888. eCollection 2021.

Authors

Emma J Kinrade¹, Stuart D R Galloway²

Affiliations

¹ Department of Occupational Therapy and Human Nutrition and Dietetics, School of Health and Life Sciences, Glasgow Caledonian University, Glasgow, United Kingdom.
² Physiology, Exercise and Nutrition Research Group, Faculty of Health Sciences and Sport, University of Stirling, Stirling, United Kingdom.

Abstract

Carbohydrate (CHO) intake recommendations for events lasting longer than 3h indicate that athletes should ingest up to 90g.h.^-1 of multiple transportable carbohydrates (MTC). We examined the dietary intake of amateur (males: n=11, females: n=7) ultra-endurance runners (mean age and mass 41.5±5.1years and 75.8±11.7kg) prior to, and during a 24-h ultra-endurance event. Heart rate and interstitial glucose concentration (indwelling sensor) were also tracked throughout the event. Pre-race diet (each 24 over 48h) was recorded via weighed intake and included the pre-race meal (1-4h pre-race). In-race diet (24h event) was recorded continuously, in-field, by the research team. Analysis revealed that runners did not meet the majority of CHO intake recommendations. CHO intake over 24-48h pre-race was lower than recommended (4.0±1.4g·kg^-1; 42±9% of total energy), although pre-race meal CHO intake was within recommended levels (1.5±0.7g·kg^-1). In-race CHO intake was only in the 30-60g·h^-1 range (mean intake 33±12g·h^-1) with suboptimal amounts of multiple transportable CHO consumed. Exercise intensity was low to moderate (mean 68%HR_max 45%VO_2max) meaning that there would still be an absolute requirement for CHO to perform optimally in this ultra-event. Indeed, strong to moderate positive correlations were observed between distance covered and both CHO and energy intake in each of the three diet periods studied. Independent t-tests showed significantly different distances achieved by runners consuming ≥5 vs. <5g·kg^-1 CHO in pre-race diet [98.5±18.7miles (158.5±30.1km) vs. 78.0±13.5miles (125.5±21.7km), p=0.04] and ≥40 vs. <40g·h^-1 CHO in-race [92.2±13.9miles (148.4±22.4km) vs. 74.7±13.5miles (120.2±21.7km), p=0.02]. Pre-race CHO intake was positively associated with ultra-running experience, but no association was found between ultra-running experience and race distance. No association was observed between mean interstitial glucose and dietary intake, or with race distance. Further research should explore approaches to meeting pre-race dietary CHO intake as well as investigating strategies to boost in-race intake of multiple transportable CHO sources. In 24-h ultra-runners, studies examining the performance enhancing benefits of getting closer to meeting pre-race and in-race carbohydrate recommendations are required.

Keywords: continuous glucose monitors; exercise; multiple transportable carbohydrates; nutrition; sport.