REF-064 · Décombaz et al., 2011 · Medicine & Science in Sports & Exercise, Vol. · Paper

Fructose (or Galactose) Added to Maltodextrin Doubles Post-Exercise Liver Glycogen Synthesis vs Glucose

Blimited evidenceMeasured on trained to highly trained athletesWritten before October 2026, being re-checked

Participants

n=10 well-trained male cyclists; three experimental sessions at least 1 week apart. After a standard exercise protocol to exhaustion, subjects drank one of three 15% carbohydrate solutions — FRU (maltodextrin + fructose, 2:1), GAL (maltodextrin + galactose, 2:1) or GLU (maltodextrin + glucose, 2:1) — each delivering 69 g CHO/h over 6.5 h of recovery. Liver glycogen was followed by ¹³C magnetic resonance spectroscopy.

Overview

Décombaz et al. compared how three maltodextrin-based drinks restore liver glycogen after exhaustive exercise. Liver glycogen concentration rose faster with FRU (24 ± 2 mmol·L⁻¹·h⁻¹, P < 0.001) and GAL (28 ± 3, P < 0.001) than with GLU (13 ± 2). Liver volume increased with FRU (9 ± 2%) and GAL (10 ± 2%) but not GLU (2 ± 1%, NS).

Net glycogen synthesis was linear and faster with FRU (8.1 ± 0.6 g/h, P < 0.001) and GAL (8.6 ± 0.9 g/h, P < 0.001) than with GLU (3.7 ± 0.5 g/h).

Conclusion: when ingested at a rate designed to saturate intestinal CHO transport, maltodextrin drinks with added fructose or galactose were twice as effective as maltodextrin + glucose at restoring liver glycogen in short-term post-exercise recovery. Muscle glycogen was not the outcome of this study.

Protocol

Double-blind, randomised triple crossover: 10 well-trained male cyclists, three experimental sessions separated by at least 1 week (from the abstract)
After a standard exercise protocol to exhaustion, one of three 15% carbohydrate drinks — maltodextrin + fructose (2:1), maltodextrin + galactose (2:1) or maltodextrin + glucose (2:1) — each providing 69 g CHO/h during 6.5 h of recovery
Measures: liver glycogen concentration and liver volume by 13C magnetic resonance spectroscopy; net liver glycogen synthesis rate

Key Findings

Liver glycogen synthesis rate: FRU 8.1 ± 0.6 and GAL 8.6 ± 0.9 g/h vs GLU 3.7 ± 0.5 g/h — about twice as fast (arithmetic)
Liver glycogen concentration: +24 (FRU) and +28 (GAL) vs +13 mmol·L⁻¹·h⁻¹ (GLU)
Liver volume: +9% (FRU), +10% (GAL), +2% NS (GLU)
Drinks: 2:1 maltodextrin : second sugar, 15% solution, 69 g CHO/h for 6.5 h — a recovery protocol, not an in-race one

Practical Application

In 10 well-trained cyclists recovering from exhaustive exercise, a 2:1 maltodextrin + fructose drink (69 g CHO/h) rebuilt liver glycogen at 8.1 g/h versus 3.7 g/h for maltodextrin + glucose — twice as fast; galactose did the same (8.6 g/h) — so post-ride recovery carbohydrate should include fructose (fruit, juice, sucrose, a mixed-sugar drink) rather than glucose/maltodextrin alone when liver stores need refilling for a session later the same day or the next morning.
Not from this paper; the base's own practice: for in-race fuelling above ~60 g/h we also use glucose + fructose mixtures, but that is for intestinal absorption during exercise — see REF-066 — not what this recovery study measured.
Inference, not tested here: since fructose is preferentially taken up by the liver, the mixed drink protects the liver store without costing muscle glycogen, which the glucose fraction still supplies; muscle glycogen was not measured here.

Limitations

n=10 men, recovery setting with a fixed 69 g/h intake; no performance test and no muscle glycogen measurement.
Only the 2:1 maltodextrin : sugar ratio was tested; the study says nothing about other ratios or about intake during exercise.
Galactose is not a practical race food; the fructose finding is the transferable one.
How this entry was checked and changed
Why this level

regraded 2026-09-27 from B+: crossover, n=10

Content correction 2026-09-27
"Optimal ratio 50-50 glucose:fructose" -> the study used 2:1 maltodextrin : fructose (or galactose); no other ratio was tested.
Removed invented in-race figures: "total carbohydrate absorption 2.0-2.5 g/min vs 1.2 g/min", "1.5-2.0 g/min = 90-120 g/h", ">3 h events", "muscle glycogen maintained via glucose pathway" — the study measured liver glycogen during 6.5 h of post-exercise recovery, not absorption during exercise.
Sport "running" -> cycling (well-trained male cyclists); Tier 4-5 -> 2-3 (well-trained, not elite); Level B+ -> B (crossover, n=10); title now names the actual comparison (maltodextrin + fructose/galactose vs maltodextrin + glucose).
2026-09-28: added Protocol from the abstract (Europe PMC/PubMed PMID 21407126).