REF-1750 · Norte et al., 2026 · Scandinavian Journal of Medicine & Science in Sports, · Paper · PubMed
In 11 trained cyclists fed 80 g/h of carbohydrate gels over 3 h at 95% of the gas exchange threshold, swapping four of the gels for a bicarbonate gel (20 g of bicarbonate in all) raised 12-min time-trial power afterwards by 12 W (95% CI 3-22; 251 vs 239 W, fresh 269 W), with no difference in 6-s sprints, a 2-min time trial or gut symptoms; one small crossover, not fully blinded, gels provided by MNSTRY, the brand of both gels tested. Read in full
Main caveat: One crossover of 11; not fully blinded, because the bicarbonate gel's taste and texture differ, on self-paced tests where expectancy can move power (the…
Norte and colleagues (Liverpool John Moores University, with World Athletics co-authors) asked whether bicarbonate taken during a long ride, in a commercial gel that also carries carbohydrate, protects hard efforts at the end.
Eleven trained cyclists (8 men, 3 women) rode 3 h at 95% of the gas exchange threshold twice, each time taking 80 g/h of carbohydrate as 40-g glucose-fructose gels; in one trial four of the gels (at 0, 30, 90 and 150 min) were the bicarbonate version, 5 g each (4.5 g sodium and 0.5 g potassium bicarbonate), giving 20 g in all, about 0.27 g/kg.
They then repeated a power profile done fresh on another day. With bicarbonate, 12-min time-trial power was 12 W higher (251 vs 239 W; 95% CI 3-22 W; p = 0.01; g = 1.07), about 6% by the authors' mean of individual differences, though both stayed below the fresh 269 W. Sprints and the 2-min time trial did not differ between conditions.
Blood bicarbonate rose by 4.3 mmol/L more than with carbohydrate alone, gut symptoms stayed mild and identical, and fuel use during the ride did not change.
The authors conclude that bicarbonate and carbohydrate taken together during prolonged exercise improve a 12-min time trial in a fatigued state, with little gut discomfort, pending confirmation in larger and elite groups and in real racing.
Participants
n = 11 trained cyclists (8 men, 3 women); 12 recruited, one excluded for not following the diet.
Age 37 ± 10 years; body mass 75 ± 10 kg; cycling experience 6 ± 2 years; training 9 ± 3 h/week over 5 ± 1 sessions.
VO2max 53.0 ± 4.5 mL/kg/min; power at the gas exchange threshold 191 ± 34 W; peak power 375 ± 62 W; trial power 181 ± 32 W (2.4 ± 0.2 W/kg).
Inclusion: >5 h/week, VO2max >45 mL/kg/min, regular local time trials or used to self-paced maximal efforts, used to ≥80 g/h of carbohydrate at least once a week, no buffering agents; women naturally menstruating with cycles of 21-35 days and no hormonal contraception (cycle phase at testing is not reported).
Protocol
Visit 1: lactate step test, ramp test for VO2max and the gas exchange threshold (V-slope), then a 1-h familiarisation ride with two bicarbonate gels.
Visit 2: fresh power profile on a Wattbike: 3 × 6-s all-out sprints (1 min apart), 5 min easy, a 2-min time trial, 15 min easy, a 12-min time trial; power hidden, time and cadence shown.
Visits 3-4, 6-8 days apart, counterbalanced: 24 h of rest and a set diet (8 g/kg carbohydrate, 2 g/kg protein, 1 g/kg fat), breakfast of 2 g/kg carbohydrate about 2 h before; 180 min at 95% of the gas exchange threshold on a Lode ergometer; then, within 3 min, the same power profile on the Wattbike.
Feeding: a 40-g gel every 30 min from 0 to 150 min, 200 mL of water with each (1.2 L), water otherwise to thirst. Carbohydrate trial: six standard gels. Bicarbonate trial: bicarbonate gels at 0, 30, 90 and 150 min, standard gels at 60 and 120 min. A final standard gel at 180 min in both trials. Bicarbonate dose fixed at 20 g, 0.27 ± 0.04 g/kg (0.23-0.35).
Measures: capillary pH, bicarbonate and electrolytes hourly and after each effort; glucose and lactate every 30 min; heart rate, RPE, gas exchange for substrate use; gut symptoms on a 0-10 scale at every gel; gel sweetness, pleasantness and urge to eat.
Blinding: participants and the investigator running the trials could not be fully blinded; the bicarbonate gel's taste and texture differ.
Funding and interests: funded by a Portuguese Foundation for Science and Technology doctoral grant to the first author; the nutrition products were provided by MNSTRY (Freudental, Germany), whose name both gels carry, and the blood analyser and its consumables by Siemens Healthineers, both stated to have had no role in design, data collection, analysis, interpretation or the decision to publish; one author (Shepherd) lists an affiliation with Precision Fuel & Hydration, Ltd (Christchurch, UK), which the conflict statement does not mention.
Key Results
Power after the 3-h ride (mean ± SD):
| Test | Fresh | Carbohydrate | Carbohydrate + bicarbonate | Between conditions |
|---|---|---|---|---|
| 12-min time trial, W | 269 ± 55 | 239 ± 66 | 251 ± 53 | +12 W (95% CI 3-22), p = 0.01, g = 1.07 |
| 2-min time trial, W | 383 ± 84 | 330 ± 91 | 337 ± 83 | p = 0.888 (abstract: +6 W, g = 0.32) |
| 6-s sprints, mean power, W | 899 ± 271 | 866 ± 314 | 879 ± 304 | not significant (abstract: +12 W, p = 1.00, g = 0.18) |
| 6-s sprints, peak power, W | 1021 ± 303 | 998 ± 336 | 984 ± 326 | p = 0.301 across all three |
Both fatigued conditions were below fresh in the 2-min and 12-min time trials (p < 0.05); sprints did not fall significantly from fresh. No order effect for either time trial.
Three of 11 did not improve the 12-min time trial with bicarbonate; two of them showed no fall in 12-min power from fresh to fatigued.
Blood and other responses:
Bicarbonate: higher with bicarbonate from 60 min on, by 4.29 mmol/L on average (95% CI 3.69-4.89); peak at 180 min 31.07 ± 1.67 vs 24.56 ± 1.53 mmol/L; rise from baseline to individual peak 5.80 ± 2.17 mmol/L (2.80-8.80). pH higher by 0.06 (0.05-0.07).
Dose and response: the bicarbonate rise tracked the dose per kg (r = 0.778, p = 0.005); neither the rise (r = 0.548, p = 0.081) nor the dose per kg (r = 0.363, p = 0.272) was significantly related to the time-trial gain.
Lactate: higher with bicarbonate after the efforts (for example +2.49 mmol/L after the 12-min time trial, 95% CI 1.16-3.81).
Substrate use during the ride: no difference: RER 0.90 in both; carbohydrate oxidation 2.22 vs 2.17 g/min; total carbohydrate 399 vs 391 g and fat 79 vs 80 g; energy expenditure, heart rate, VO2, glucose and RPE did not differ.
Gut: symptoms negligible in both; no score above 4 (mild) in anyone, five riders reaching 4 at some point; cumulative scores alike (p = 0.941).
Taste: the bicarbonate gel was rated less pleasant at most time points and less sweet at 90 and 150 min; some riders diluted it in water. Fluid intake alike (2007 vs 2095 mL).
Practical Application
In trained amateurs already fed 80 g/h, taking about 20 g of bicarbonate in gels during a 3-h ride lifted 12-min time-trial power at the end by about 12 W (about 5-6%) without gut trouble; sprints and a 2-min effort were not helped. One small trial, not fully blinded, with gels provided by the brand under test.
Where this extends [SYNTH-32]: the guide calls carbohydrate the within-ride lever with most of the trial evidence and cites this trial as the one small crossover of a second lever on top of carbohydrate. This trial tests that second lever and finds a late-effort gain, but neither condition brought the 12-min power back to its fresh value, so it raises the floor of the fade rather than removing it, as the guide says of carbohydrate.
Where it extends [SYNTH-67]: the guide's bicarbonate advice is 0.3 g/kg taken 60-180 min before efforts of 30 s to 12 min (REF-354). Here the dose was a fixed 20 g (0.23-0.35 g/kg) spread through the first 150 min of the ride, and the effort that improved was 12 min long; a direct comparison with the usual pre-exercise dose was not made, so this does not show the during-ride route is better.
[SYNTH-02] row: 80 g/h of glucose-fructose gels over 3 h sits in the amateur "3-6 h" cell (up to 90 g/h), in riders already used to that intake; it still left a fall in 12-min power of about a ninth from fresh (our arithmetic: 239 vs 269 W), in line with the guide's point that fuel blunts the late loss but does not remove it.
Inference, not tested here: rehearse a bicarbonate gel in training before any race, as SYNTH-67 asks for bicarbonate in general; a race with surges, a heavier rider (lower dose per kg) or a lower carbohydrate intake may respond differently.
Limitations
One crossover of 11; not fully blinded, because the bicarbonate gel's taste and texture differ, on self-paced tests where expectancy can move power (the authors say so).
Fixed test order: the 12-min time trial came after sprints and a 2-min effort, so the gain may reflect better recovery between efforts rather than durability from the 3-h ride itself (the authors cannot separate the two).
Only one of three tests improved; the sprints and 2-min time trial did not.
A fixed 20-g dose gave 0.23-0.35 g/kg; the rise in blood bicarbonate tracked the dose, but the small sample could not show a dose-performance link.
Everyone received carbohydrate; the effect of bicarbonate without carbohydrate, or compared with taking it before the ride, was not tested. A steady laboratory ride, not a race.
No reliability data for the fatigued power profile; three riders did not respond, two of whom had shown no fatigue.
Industry ties: the nutrition products were provided by MNSTRY, the brand of both gels tested, and the blood analyser and consumables by Siemens Healthineers; both stated to have had no role. One author is affiliated with Precision Fuel & Hydration, Ltd, which the conflict statement does not mention. Funding came from a Portuguese Foundation for Science and Technology (FCT) doctoral grant to the first author.
The same first author and laboratory used the same 3-h protocol in REF-1122; whether any riders took part in both is not stated.
How this entry was checked and changed
Why this level
a crossover of 11 (the rubric's B band) taken one step down because neither the riders nor the investigator could be fully blinded on self-paced, effort-dependent tests, so expectancy cannot be excluded (the authors' own limitation), with the gels provided by the brand under test