REF-057 · Burke et al., 1993 · Journal of Applied Physiology, Vol. · Paper

Glycemic Index Affects Glycogen Resynthesis Rate

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

Participants

n=5 well-trained cyclists. Two trials 1 week apart: glycogen depletion (2 h at 75% VO2max + four 30-s sprints), then 24 h of rest on a diet of exclusively high-carbohydrate foods, once high-GI and once low-GI. Total carbohydrate 10 g/kg over the 24 h, split evenly between meals at 0, 4, 8 and 21 h post-exercise. Biopsies immediately after exercise and at 24 h.

Protocol

Within-subject crossover: five well-trained cyclists, two trials 1 wk apart (from the abstract).
Glycogen-depleting exercise each time: 2 h at 75% of maximal O2 uptake followed by four 30-s sprints.
24 h of rest on a diet composed exclusively of high-carbohydrate foods — high-GI in one trial, low-GI in the other; total carbohydrate 10 g/kg of body mass, evenly distributed between meals eaten 0, 4, 8 and 21 h post-exercise.
Measures: blood glucose and insulin (before and immediately after exercise, before each meal and 30, 60 and 90 min post-prandially); vastus lateralis biopsies immediately after exercise and after 24 h.

Overview

Burke, Collier and Hargreaves asked whether the glycemic index of post-exercise carbohydrate changes how much muscle glycogen is stored over 24 h when the carbohydrate amount is fixed. With the immediate post-exercise meal excluded, the summed glucose and insulin responses to the meals were greater on the high-GI diet (P ≤ 0.05).

The 24-h increase in muscle glycogen was greater with the high-GI diet: 106 ± 11.7 vs 71.5 ± 6.5 mmol/kg wet weight (P = 0.02) — about 48% more glycogen stored (arithmetic on the two means). Conclusion: the most rapid increase in muscle glycogen during the first 24 h of recovery is achieved by consuming high-GI foods.

Key Findings

24-h muscle glycogen gain: 106 ± 11.7 (high-GI) vs 71.5 ± 6.5 mmol/kg wet wt (low-GI), P = 0.02
That is roughly 48% more storage with the high-GI diet at identical carbohydrate intake (10 g/kg/24 h) — arithmetic
Post-meal glucose and insulin areas were greater after the high-GI meals (immediate post-exercise meal excluded)

Practical Application

In 5 well-trained cyclists eating the same 10 g/kg of carbohydrate over 24 h, a high-GI diet restored 106 mmol/kg of muscle glycogen versus 71.5 with a low-GI diet (P = 0.02) — when the next hard session is within a day, choose fast carbohydrate (white rice, bread, potatoes, sports drinks, ripe fruit) over fibre-rich, slow sources for the recovery meals.
Not from this paper; the base's own practice: the effect matters when hard days sit back to back; on ordinary days low-GI foods are fine for normal meals, and total carbohydrate dose plus timing (REF-056) comes before glycemic index.
Inference, not tested here: the mechanism the authors point to is the larger glucose and insulin response to high-GI meals; whether the difference persists beyond 24 h was not measured.

Limitations

1993, five well-trained cyclists — a foundational study whose absolute numbers have been refined by three decades of subsequent work.
Glycemic index of whole meals behaves differently from the isolated test foods used here, and GI itself is a crude descriptor of a mixed meal.
Glycogen resynthesis over 24 h is a laboratory outcome; the performance consequence depends on how soon the next session actually is.
Total carbohydrate dose and timing dominate resynthesis; GI is a second-order variable that this era of research treated as first-order.
Male trained cyclists; no women, no masters, and no athletes eating under energy restriction.
How this entry was checked and changed
Why this level

regraded 2026-09-27 from B+: crossover, n=5

Content correction 2026-09-27
"High-GI +35-45% faster resynthesis" -> the abstract's 106 vs 71.5 mmol/kg over 24 h (about 48% more, arithmetic); design and dose (10 g/kg over 24 h, meals at 0/4/8/21 h) added.
Removed unsourced "GI >95 glucose or maltodextrin", "fructose slower but superior liver glycogen", "50% high-GI + 50% fructose", ">4 h", "high-GI + protein synergizes" — none is in the abstract (for fructose and liver glycogen see REF-064).
Level B+ -> B (crossover, n=5).
2026-09-28: added Protocol from the abstract (Europe PMC, DOI 10.1152/jappl.1993.75.2.1019, PMID 8226443).