REF-065 · Podlogar et al., 2022 · International Journal of Sport Nutrition & Exercise Metabolism · Paper

Adding fructose to a carbohydrate-rich breakfast extended cycling time to exhaustion at the first ventilatory threshold by about 7 minutes (137 vs 130 min) in eight trained men

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

Protocol

Eight trained men (VO₂peak 62.2 ± 5.4 mL·kg⁻¹·min⁻¹), double-blind randomised crossover. Day 1 afternoon: an interval session to normalise glycogen, then a standardised high-carbohydrate diet for 4 h. Day 2 morning: breakfast of 2 g/kg carbohydrate as glucose + rice or fructose + rice (carbohydrate ratio 1:2). Two hours later: cycling at the first ventilatory threshold until task failure.

Key Findings

Time to exhaustion: 137.0 ± 22.7 min with fructose + rice vs 130.1 ± 19.9 min with glucose + rice (p = .046) — about 7 minutes, ~5%.
Blood glucose, blood lactate and the RATES of carbohydrate and fat oxidation did not differ; total carbohydrate oxidised was higher with fructose (326 vs 298 g, p = .009) only because the ride lasted longer.
Liver glycogen was not measured; the rationale is that fructose restores liver glycogen better than glucose after an overnight fast.

Practical Application

For a long event, let part of the pre-race breakfast carbohydrate come from fructose. A breakfast of ~2 g/kg in which about a third came from fructose rather than glucose extended endurance capacity by ~7 min in an effort of over two hours.
It is a tweak, not a pillar: one small crossover, one dose, p = .046. Worth doing because it costs nothing, not worth building a race plan around.

Limitations

n = 8 trained men, one trial per condition, p = .046.
Time to exhaustion at a fixed intensity, not a race or time trial.
One dose and ratio (2 g/kg, 1:2); other amounts untested. The liver-glycogen mechanism is assumed, not measured.
How this entry was checked and changed
Why this level

regraded 2026-09-26 from B+: crossover, n=8

Content correction 2026-09-26

Until today this entry said the breakfast was 200–250 g of carbohydrate with 60–80% of it fructose, eaten 2–3 h before "2–3 hour cycling efforts" by elite athletes, and that it worked by raising liver glycogen.

The paper gave 2 g/kg of carbohydrate as glucose + rice or fructose + rice in a 1:2 ratio, 2 h before cycling at VT1 to exhaustion, in trained (not elite) men, and did not measure liver glycogen — that was the hypothesis, not a result. The tier and sport lines were wrong for the same reason and are corrected.