PURPOSE: In the laboratory, the ingestion of multiple-transportable carbohydrates (fructose, glucose) in beverages at high rates (>1.3 g·min-1) enhances exogenous carbohydrate oxidation, fluid absorption, gut comfort, and performance, relative to single carbohydrate equivalents. In competition, however, endurance athletes prefer to ingest carbohydrate in a solid-gel-drink format but whether multiple-transportable carbohydrates in the mixed format also enhance competition performance is unknown. The objective of the study was to determine the effect of multiple- vs. single-transportable carbohydrate on triathlon race performance when ingested in the common format of bars, gels and drinks.
METHODS: A double-blind randomized controlled trial was conducted within two sanctioned half-ironman triathlon races held 3 weeks apart in 74 well-trained male triathletes (18-60 y; >2 y competition experience). Carbohydrate was ingested before (94 g) an during the race from bars (25%), gels (35%) and drink (40%) comprising a 2:1 glucose/maltodextrin:fructose ratio vs isocaloric placebo glucose/maltodextrin only. Ingestion was apportioned by unit-distance covered during the cycle (2.5 g·km-1) and run (7.8 g·km-1) averaging 78.6 g·h-1 (SD 6.6). Post-race 0-10 unit Likert-type scales were completed to assess gut comfort and energy.
RESULTS: The trial returned low dropout rate (9%), high compliance and sensitivity (typical error 2.2%), but the effect of the multiple-transportable carbohydrate on overall performance time (-0.6%, 95%CI -1.8%, 0.7%), swim, bike, and run times, and on nausea, gut comfort and perceived energy was of trivial-small magnitude without statistical significance. Within-subject covariate adjustment for pre-exercise body weight, heat stress, and within-race change in body weight had negligible impact on outcomes.
CONCLUSION: Multiple-transportable carbohydrate ingested in the common bar-gel-drink format provided negligible benefit to long-distance triathlon performance. The experience of the large sample intervention study showed that in-competition clinical trials offer ecological validity, and high throughput rate, compliance, and sensitivity for evaluation of health and performance interventions in athletes. Funding: Nestec Ltd, Switzerland.