Fructose Coingestion Does Not Accelerate Postexercise Muscle Glycogen Repletion

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Abstract

BACKGROUND: Post-exercise muscle glycogen repletion is largely determined by the systemic availability of exogenous carbohydrate provided. PURPOSE: This study aimed to assess the effect of the combined ingestion of fructose and glucose on post-exercise muscle glycogen repletion when optimal amounts of carbohydrate are ingested. METHODS: Fourteen male cyclists (age: 28+/-6 y; Wmax: 4.8+/-0.4 W.kg) were studied on 3 different occasions. Each test day started with a glycogen-depleting exercise session. This was followed by a 5 h recovery period, during which subjects ingested 1.5 g.kg.h glucose (GLU), 1.2 g.kg.h glucose + 0.3 g.kg.h fructose (GLU+FRU), or 0.9 g.kg.h glucose + 0.6 g.kg.h sucrose (GLU+SUC). Blood samples and gastrointestinal distress questionnaires were collected frequently and muscle biopsies were obtained at 0, 120, and 300 min after cessation of exercise to measure muscle glycogen content. RESULTS: Plasma glucose responses did not differ between treatments (ANOVA, P=0.096), but plasma insulin and lactate concentrations were elevated during GLU+FRU and GLU+SUC when compared to GLU (P<0.01). Muscle glycogen content immediately following exercise averaged 207+/-112, 219+/-107 and 236+/-118 mmol.kg dry weight in the GLU, GLU+FRU and GLU+SUC treatment, respectively (P=0.362). Carbohydrate ingestion increased muscle glycogen concentrations during 5 h of post-exercise recovery to 261+/-98, 289+/-130 and 315+/-103 mmol.kg dry weight in the GLU, GLU+FRU and GLU+SUC treatment, respectively (P<0.001), with no differences between treatments (time x treatment, P=0.757). CONCLUSION: Combined ingestion of glucose plus fructose does not further accelerate post-exercise muscle glycogen repletion in trained cyclists when ample carbohydrate is ingested. Combined ingestion of glucose (polymers) plus fructose or sucrose reduces gastrointestinal complaints when ingesting large amounts of carbohydrate.
Original languageEnglish
Pages (from-to)907-912
Number of pages6
JournalMedicine and Science in Sports and Exercise
Volume48
Issue number5
DOIs
Publication statusPublished - May 2016

Keywords

  • CYCLING
  • RECOVERY
  • CARBOHYDRATE SUPPLEMENTATION
  • MULTIPLE TRANSPORTABLE
  • CARBOHYDRATE INGESTION
  • EXERCISE PERFORMANCE
  • SKELETAL-MUSCLE
  • GLUCOSE
  • PROTEIN
  • OXIDATION
  • RESYNTHESIS
  • METABOLISM
  • SUCROSE

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