REF-1740 · Fleitas-Paniagua et al., 2026 · Scandinavian Journal of Medicine & Science in Sports, · Paper · PubMed

In 12 recreationally trained men, 40 g/h of carbohydrate during 90 min in the lower heavy domain made a following 4-km time trial faster than placebo (8.3 vs 8.6 min), while 90 g/h did not differ from placebo; after 120 min of moderate riding or 60 min in the upper heavy domain the three drinks did not differ significantly (one small crossover, read from its abstract)

Main caveat: One crossover of 12 men; nine conditions and several pairwise comparisons in a small sample, with no correction for multiple testing described in the abstract.
limited, mixed evidenceMeasured on recreational to trained athletesRead from the abstract only

Fleitas-Paniagua and colleagues (the Murias laboratory) asked two questions: whether carbohydrate during a constant-power ride helps a 4-km time trial afterwards, and whether that depends on the intensity domain of the ride; and whether a dose above the recommended one adds anything.

Twelve recreationally trained men rode three kinds of bout, each under three drinks, in nine randomised visits: 120 min in the moderate domain, 90 min in the lower part of the heavy domain and 60 min in its upper part, with placebo, 40 g/h (which the authors call the recommended dose) or 90 g/h (which they call high).

Only after the 90-min lower-heavy bout did a dose change the time trial: 40 g/h was faster than placebo (8.3 vs 8.6 min, p = 0.017), and 90 g/h (8.5 min) was not. After the moderate and the upper-heavy bouts the three conditions did not differ.

The authors conclude that the recommended dose helped after lower-heavy work only, and that the higher dose brought no benefit after any bout.

Participants

n = 12 recreationally trained males.
Age, VO2max, training history, habitual carbohydrate intake during exercise and gut training: not in the abstract.

Protocol

Visit 1: step-ramp-step test to estimate GET and MMSSest.
Nine randomised visits: three bouts × three drinks.
MOD: 120 min at 90% of GET (moderate domain).
HVY1: 90 min at 20% of the way from GET to MMSSest (lower heavy domain).
HVY2: 60 min at 80% of the way from GET to MMSSest (upper heavy domain).
Drinks: placebo, 40 g/h (R-CHO), 90 g/h (H-CHO).
Outcome: a 4-km time trial straight after each bout.
Not in the abstract: carbohydrate type and form, fluid volume, feeding schedule, blinding, pre-trial diet, washout between visits, and how the order was randomised.

Key Results

4-km time-trial time, minutes (mean ± SD):

Prior boutPlacebo40 g/h90 g/hp
HVY1, 90 min lower heavy8.6 ± 0.98.3 ± 0.78.5 ± 0.90.017 (40 g/h vs placebo; 90 g/h not different from placebo)
MOD, 120 min moderate8.8 ± 1.38.6 ± 1.18.6 ± 1.10.589
HVY2, 60 min upper heavy8.8 ± 1.18.6 ± 0.98.7 ± 1.00.465
The SDs are of the times, not of the paired differences; the variability of the gains is not in the abstract.
A direct comparison of 90 g/h with 40 g/h is not reported in the abstract.

Practical Application

For a recreational rider, about 40 g/h was enough to help a hard finish after 90 min of steady heavy work, and 90 g/h did not help more in this trial; after 2 h of easy riding or 1 h of harder riding the drinks did not differ significantly. One small crossover in men, read from its abstract.
[SYNTH-02] rows: the HVY1 session (90 min plus an 8-min finish) sits at the border of the "<90 min" row (30-60 g/h from about 1 h) and the amateur cell of the "90 min-3 h" row (60 g/h; up to 90 only on a hard, rehearsed ride past ~2-2.5 h). The 40 g/h result agrees with the 30-60 g/h range, and the null at 90 g/h agrees with not handing an amateur 90 g/h by default on a ride this short. The trial did not test 60 g/h, the amateur default.
The null after 120 min of moderate riding is not evidence against fuelling a 2-h ride. It is one 4-km test after a low-cost bout, with no variability for the differences given; the base's 2-h evidence on power after harder work is REF-145.
Inference, not tested here: why 90 g/h did not beat placebo is not explained in the abstract; gut tolerance in riders who had not practised high intakes is one possibility, and it is the reason SYNTH-02 has the rate earned in training.

Limitations

One crossover of 12 men; nine conditions and several pairwise comparisons in a small sample, with no correction for multiple testing described in the abstract.
The 40 g/h benefit appeared in one of three bouts, and the absolute gap was about 0.3 min over about 8.5 min.
The 90 g/h arm was not compared with 40 g/h in the abstract, so "no added benefit" means only "not different from placebo".
Carbohydrate type (single sugar or blend), gut training, blinding and the feeding schedule are not in the abstract; if the drink was a single sugar, 90 g/h is above the ~60 g/h at which SYNTH-02 switches to a glucose-fructose blend; the abstract does not say.
The same laboratory ran the same 90-min heavy bout in 12 women (REF-1742); the two abstracts describe different participants (men here, women there).
Written from the abstract and the PubMed record; full text not read.
How this entry was checked and changed
Why this level

a crossover of 12 (the rubric's B band) taken one step down because it is read from the abstract only, which gives no variability for the differences, no blinding, carbohydrate type or gut-training status, and no direct test of 90 against 40 g/h