Multiple-Transportable Carbohydrate Effect on Long-Distance Triathlon Performance

Med Sci Sports Exerc. 2017 Aug;49(8):1734-1744. doi: 10.1249/MSS.0000000000001278.


The ingestion of multiple (2:1 glucose-fructose) transportable carbohydrate in beverages at high rates (>78 g·h) during endurance exercise enhances exogenous carbohydrate oxidation, fluid absorption, gut comfort, and performance relative to glucose alone. However, during long-distance endurance competition, athletes prefer a solid-gel-drink format, and the effect size of multiple-transportable carbohydrate is unknown.

Purpose: This study aimed to determine the effect of multiple-transportable carbohydrate on triathlon competition performance when ingested within bars, gels, and drinks.

Methods: A double-blind randomized controlled trial was conducted within two national-body sanctioned half-ironman triathlon races held 3 wk apart in 74 well-trained male triathletes (18-60 yr; >2 yr competition experience). Carbohydrate comprising glucose/maltodextrin-fructose (2:1 ratio) or standard isocaloric carbohydrate (glucose/maltodextrin only) was ingested before (94 g) and during the cycle (2.5 g·km) and run (7.8 g·km) sections, averaging 78.6 ± 6.6 g·h, partitioned to bars (25%), gels (35%), and drink (40%). Postrace, 0- to 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%). The effect of multiple-transportable carbohydrate on performance time was -0.53% (95% confidence interval = -1.30% to 0.24%; small benefit threshold = -0.54%), with likelihood-based risk analysis supporting adoption (benefit-harm ratio = 48.9%:0.3%; odds ratio = 285:1). Covariate adjustments for preexercise body weight and heat stress had negligible impact performance. Multiple-transportable carbohydrate possibly lowered nausea during the swim and bike; otherwise, effects on gut comfort and perceived energy were negligible.

Conclusions: Multiple-transportable (2:1 maltodextrin/glucose-fructose) compared with single-transportable carbohydrate ingested in differing format provided a small benefit to long-distance triathlon performance, inferred as adoption worthy. Large sample in-competition randomized trials offer ecological validity, high participant throughput, compliance, and sensitivity for evaluation of health and performance interventions in athletes.

Trial registration: NCT02031783.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Bicycling / physiology*
  • Body Weight
  • Competitive Behavior / physiology
  • Cross-Over Studies
  • Diet
  • Dietary Carbohydrates / administration & dosage*
  • Double-Blind Method
  • Energy Drinks
  • Food
  • Fructose / administration & dosage
  • Gastrointestinal Diseases / prevention & control
  • Glucose / administration & dosage
  • Humans
  • Male
  • Middle Aged
  • Physical Endurance / physiology*
  • Polysaccharides / administration & dosage
  • Running / physiology*
  • Swimming / physiology*
  • Temperature
  • Young Adult


  • Dietary Carbohydrates
  • Polysaccharides
  • Fructose
  • maltodextrin
  • Glucose

Associated data