OBJECTIVE: Ingesting a mix of glucose and fructose during exercise increases exogenous carbohydrate oxidation while minimizing gastrointestinal (GI) distress. Several studies have suggested that a glucose-to-fructose ratio of 1.2:1 to 1:1 is optimal. No studies have quantified saccharides consumed during a nonsimulated endurance event. The aim of this investigation was to quantify saccharide sources used during an ultra-endurance triathlon and provide a resource for athletes desiring to manipulate the saccharide content of carbohydrate consumed during training and competition.
METHODS: Participant self-report and direct measurement were used to assess foods and beverages consumed during an ultra-endurance (70.3-mile) triathlon. Manufacturer-supplied information, high-performance liquid chromatography, and the US Department of Agriculture Food Database were used to quantify saccharide profiles of foods and beverages. Participants reported GI distress during the run on a 0-10 scale. A subanalysis examined associations between saccharides and GI distress among participants consuming ≥ 50 g·h(-1) of carbohydrate during the swim and cycle.
RESULTS: Fifty-four participants (43 men) used 80 foods and beverages with a unique saccharide profile. Of total carbohydrate, median proportions as glucose, fructose, and sucrose were 64%, 5%, and 10%, and only 7 foods (8.8%) had a glucose-to-fructose ratio of 1.2:1 to 1:1. The median glucose-to-fructose ratio of carbohydrate ingested was 2.9:1 (2.2:1-5.3:1). Twenty participants consumed ≥ 50 g·h(-1) of carbohydrate during the swim and cycle, and significant correlations with incident GI distress at mile 1 of the run were found for glucose (r = 0.480, p = 0.032) and fructose (r = -0.454, p = 0.044).
CONCLUSIONS: The majority of foods and beverages consumed during an ultra-endurance triathlon did not contain an optimal saccharide profile. Furthermore, glucose intake was associated with greater GI distress among participants consuming a high rate of carbohydrate.
