The Modern Carbohydrate Playbook: How to Fuel Endurance in 2026

TL;DR

• The pro peloton's "120 g/hour revolution" is real, but for most age-group athletes the performance edge over a well-executed 60–90 g/h plan is small, inconsistent, and only earned after months of gut training.
• The biggest fueling mistake recreational athletes make is mismatching intake to intensity: easy Zone 2 sessions rarely need fueling, while hard efforts over 75 minutes are dramatically undersold by "a banana and a gel."
• Recovery is mostly carbs, not the protein shake on the bottle. Hitting 1.0–1.2 g carbohydrate per kg per hour for the first 4 hours after a depleting session, plus a periodized daily total of 5–12 g/kg, moves the needle far more than any single in-race tweak.

If you want a primer on macronutrients, protein timing, and daily nutrition basics, start with our Nutrition for Endurance Athletes guide. This post goes deeper into the in-race carbohydrate science that has changed fast over the last five years.

Why Fueling Changed

Five years ago, the standard advice for long-course endurance athletes was 60–90 grams of carbohydrate per hour. The professional peloton now routinely fuels at 120 g/h and sometimes more. At the 2025 IRONMAN World Championship in Nice, Norway's Casper Stornes ran a 2:29:25 marathon — the first sub-2:30 in IM World Championship history — reportedly fueling at roughly 180 g/h on the bike and 130 g/h on the run.

Three things drove the shift, in order of importance:

1. Energy balance across stage races. Tim Podlogar, performance scientist at Tudor Pro Cycling, has noted that pros simply cannot eat enough off the bike to cover Grand Tour energy demands. Moving from 70 to 110 g/h across the roughly 80 race hours of a Grand Tour adds about 3,200 g of carbohydrate that no rider can replace at the dinner table.¹
2. Glycogen sparing and running economy. A 2025 study of elite male marathoners showed 120 g/h lowered the oxygen cost of running by about 3% versus 60 g/h.²
3. Brain effects. Carbohydrate in the mouth engages central nervous system reward pathways and reduces perceived effort independent of metabolism.³

So is the right answer to copy the pros? Not quite.

What the Science Actually Shows

The honest version of the story is more cautious than the marketing.

The most recent comprehensive review of the literature — Wilson (2025) in Sports Medicine — concluded verbatim: "Existing research does not directly support performance-enhancing effects of ingesting carbohydrate at ≥ 100 g/h versus 60–90 g/h."⁴ Podlogar himself told Velo magazine: "I don't think we have any data to suggest that 120 grams of carbohydrate per hour will improve performance over 90 grams."¹

The 2025 Ravikanti marathon study, the strongest signal yet for higher intakes, tested 8 elite male marathoners running 2 hours at lactate threshold. 120 g/h beat 60 g/h on running economy by a clear margin. But there was no statistically significant economy difference between 120 g/h and 90 g/h, and peak GI symptoms (nausea, fullness, cramps) were greatest at 120 g/h.²

A January 2026 meta-analysis pooling 31 studies and 48 effect sizes found carbohydrate ingestion does spare muscle glycogen, but the effect is small (around 24 mmol/kg dry weight over ~100 minutes of exercise), and ingestion rate was not a significant moderator. Higher rates did not spare meaningfully more glycogen than moderate ones.⁵

The takeaway: 60–90 g/h captures most of the available benefit for most athletes. Going higher is for the genuinely long, hard, and well-trained gut.

The Transporter Story (and Why Ratios Matter)

Glucose and the maltodextrin polymers that break down to glucose are absorbed in the small intestine via the SGLT1 transporter, which saturates at roughly 1.0–1.2 g/min (60–72 g/h). Fructose uses a different transporter, GLUT5, so combining the two unlocks total absorption up to around 1.7 g/min (100+ g/h). This is why every modern endurance product blends glucose (or maltodextrin) with fructose.

The ratio is dose-dependent. There is no single "magic" ratio. Asker Jeukendrup, whose lab pioneered this work, has stated plainly: "There is no optimal ratio. The ratio that is optimal will change depending on amounts ingested. If 90 g/h is ingested it should be around 2:1, but if more is ingested, for example 120 g/h, 1:1 is likely better."⁶

Total intake	Glucose : Fructose	Why
≤ 60 g/h	1:0 (glucose only) is fine	SGLT1 not yet saturated
60–90 g/h	2:1	Saturates SGLT1 with modest fructose load
90–120 g/h	1:0.8 to 1:1	Higher fructose share; SGLT1 already maxed
> 120 g/h (elite)	1:1	Maximum GLUT5 contribution

Format does not matter at a given dose. A 2022 trial showed that at 120 g/h, exogenous carbohydrate oxidation was the same whether the carbs came as a drink, a gel, a chew, or a combination.⁷ Pick what your gut and your sport can handle.

Match Intake to Intensity AND Duration

The most common amateur error is treating duration as the only variable. Intensity matters just as much.

At rest and in Zone 1–2, fat dominates as a fuel. Around 70–75% of VO₂max the "crossover" to carbohydrate occurs, and at marathon-pace or threshold-cycling intensities roughly 80–90% of energy comes from carbohydrate.⁸

This dictates a simple decision tree:

• Zone 2 under 90 min: Often no fueling needed. Train fat oxidation.
• Zone 2, 90 min to 3 h: 30–60 g/h spares glycogen for tomorrow's quality session.
• Tempo or threshold over 60–75 min: 60–90 g/h. Carbohydrate need scales with intensity, not just clock time.
• Sustained high intensity over 3 h: 90–120 g/h ceiling, with gut training.

Daily Carbohydrate Targets

In-race fueling sits on top of a daily intake foundation. The IOC consensus and joint ACSM/AND/Dietitians of Canada position stand both endorse periodizing total carbohydrate to training load.⁹¹⁰

Day type	Carbohydrate target
Rest or easy recovery	3–5 g/kg/day
Moderate (1–2 h moderate intensity)	5–7 g/kg/day
Hard or long (2+ h with intensity)	7–10 g/kg/day
Stage race or extreme	10–12 g/kg/day

Periodized fueling (sometimes called "fuel for the work required") has replaced both "always high-carb" and ketogenic approaches. Burke's "Supernova" replication trials in elite race walkers showed the high-carb group improved their 10,000 m time by 4.8% (134 s), while the low-carb/high-fat group got 2.3% slower (−86 s). A periodized-carb group improved by 2.2%.¹¹ The verdict on ketogenic diets for competitive endurance performance is settled: they impair it.

"Train low, race high" still has a place. One or two easy aerobic sessions per week in a fasted or low-carb state (morning Zone 2 before breakfast, or a "sleep-low" pattern of hard PM session followed by low-carb dinner and fasted AM Z2) can support some adaptations. Never do this on quality, long, or high-intensity sessions.

Race-Day Protocols by Event

Event	Duration	Carbohydrate target
5K, criterium, sprint tri	< 45 min	Water only. A carb mouth-rinse may help.
10K, short TT, Olympic tri bike	45–75 min	~30 g/h or one gel mid-event.
Half-marathon, sportive, Olympic tri	75 min – 2 h	30–60 g/h. One carb-drink bottle plus 1–2 gels.
Marathon, gran fondo, half-Ironman	2–4 h	60–90 g/h. Sweet spot for most age-groupers.
Ironman, century, mountain marathon	4+ h	80–120 g/h depending on gut training.
Ultra (UTMB-style)	6+ h	60–90 g/h plus real food and savory items.

A 2020 trial in elite trail runners found 120 g/h reduced muscle damage markers and improved 24-hour neuromuscular recovery versus 60 and 90 g/h, but 2 of 9 runners abandoned due to GI problems.¹² The high-intake ceiling is real, but the GI risk is real too.

Pre-Race Carb Loading

The modern protocol is 8–12 g/kg/day for 1–2 days before the race, with no depletion phase needed. For a 70 kg runner that is 560–840 g/day. The night-before-only pasta dinner is the most common amateur mistake: it is both too late and too concentrated. Expect a 2–4 lb gain (glycogen plus the ~3 g of water bound to each gram of glycogen). That is the point.

Pre-race meal: 1–4 g/kg of low-fiber, familiar carbohydrate 1–4 hours before start. White bread or bagel with honey, white rice, oatmeal, banana, sports drink. Nothing new, nothing high-fiber.

Mid-Race Mechanics

• Cadence: Take something every 15–25 minutes. The gut empties best with consistent small doses, not big intermittent ones.
• Concentration: 6–8% carbohydrate solution (60–80 g/L). Above ~10% slows gastric emptying, unless you're using a hydrogel or a specifically formulated high-concentration product.
• Fluid: 500–1000 mL/h depending on sweat rate and conditions. Dehydration over 2% body mass impairs gastric emptying and amplifies GI symptoms.
• Sodium: 300–800 mg/h in most conditions, up to 1500 mg/h for heavy or salty sweaters and hot races.
• Caffeine: 3–6 mg/kg about 45–60 min pre-race, with small (~50–100 mg) maintenance doses every 1–2 hours in long events. Caffeine and carbohydrate are synergistic: caffeine modestly boosts intestinal carb absorption.

Gut Training: The 6–10 Week Protocol

The gut is an adaptable organ. A 28-day study showed progressive high-carbohydrate training increased exogenous carbohydrate oxidation; shorter 10-day protocols also work.¹³

A practical ramp: start at 30 g/h during one or two long sessions per week, then add roughly 10 g/h each week. By weeks 6–7 you should be tolerating 80–90 g/h, and from week 8 onward you can push toward your race target (up to 120 g/h for the well-trained). The numbers are not sacred; the discipline of progressive, repeatable exposure is.

Rules:

• One or two key long sessions per week at race intake, not every ride or run.
• Pair every dose with adequate fluid (150–200 mL per 30 g carbohydrate).
• If GI symptoms appear, hold the previous step for another week before progressing.
• Use the exact products, ratios, and flavors you will race with.

Products: Gels, Drinks, Chews, Real Food, Hydrogels

Because the form of delivery does not change the physiology at a given dose,⁷ choose by practicality.

Format	Best for	Carbs per unit	Pros	Cons
Liquid drink mix (Skratch Super High-Carb, SiS Beta Fuel, Tailwind, Maurten 320, Precision PF 90)	Cycling, hot weather, athletes who can drink while running	60–100 g/bottle	Combines hydration, fuel, sodium; easy to titrate; gentle on stomach	Hard to consume at marathon pace; spillage; flavor fatigue
Gels (Maurten 100/160, SiS, GU, Precision PF 30, Neversecond)	Running, structured sessions, races needing precise timing	22–40 g/gel	Compact, precise dose, work at all intensities	Need water co-ingestion; concentrated osmolality can cause GI issues
Chews / blocks (Clif Bloks, Honey Stinger, SiS Beta Fuel chews)	Long bike rides, ultras, athletes who hate gels	4–10 g/chew	Chewing satisfaction; portion control; less concentrated	Slower to consume; require dental tolerance during exercise
Real food (banana, dates, rice cakes, sandwiches, gummy candy, sushi rice balls)	Ultras, long bike rides, multi-day events	Variable	Cheap; psychological variety; combats sweet fatigue	Variable absorption; fiber risk; harder to dose precisely
Hydrogel (Maurten)	Athletes pushing > 90 g/h with severe GI history; high-concentration delivery	Same dose, pectin/alginate matrix	Tolerated at higher concentrations; premium taste	Cost (3–4× cheaper alternatives); independent evidence weak

A practical mixing strategy for long events: use a drink mix as your hydration backbone (covers fluid, sodium, and ~30–60 g/h of carbohydrate), top up with gels every 30–45 minutes, and pre-position real food at aid stations or in special-needs bags for ultras. Keep at least 2 flavors and textures to fight palate fatigue after hour 3.

Hydrogels: Hype vs Evidence

Maurten markets its pectin/sodium-alginate hydrogel as encapsulating carbs to bypass GI distress and improve absorption. The independent peer-reviewed evidence is mostly null. Controlled trials by McCubbin (Monash) and Burke's Australian race-walker work both found no GI or performance benefit versus identical non-hydrogel drinks at 90 g/h.¹⁴ One 2021 study using a more demanding 18% carbohydrate solution at near-marathon pace did find a hydrogel benefit, suggesting the effect may surface only under severe GI stress.¹⁵

The honest verdict: Maurten products deliver their carbohydrates well, but so do cheaper options from SiS, Precision Fuel & Hydration, Skratch, Neversecond, and Amacx. Buy on taste, texture, and convenience, not hydrogel claims alone.

Recovery: Carbs Lead, Protein Supports

Rapid recovery (under 8 hours to next session, twice-a-day or stage races):

• 1.0–1.2 g carbohydrate per kg body mass per hour for the first 4 hours.
• Start within 30 minutes of finishing.
• Use high-GI sources (white rice, white potato, sports drink, fruit juice, white bread).
• Add 20–40 g protein for muscle protein synthesis, not for glycogen.

Normal recovery (24+ hours to next session):

• Hit your daily carbohydrate target (5–12 g/kg). Timing matters less than the total.
• Spread protein across 4–5 meals of 20–35 g each.

The protein co-ingestion question is settled. When carbohydrate is at the 1.2 g/kg/h optimum, adding protein does not further increase glycogen synthesis.¹⁶ Protein addition meaningfully boosts glycogen synthesis only when carb intake is below 0.8 g/kg/h, which can be useful when appetite or budget limits carb intake. Protein remains essential for muscle protein synthesis, just not as a glycogen lever.

Common Pitfalls

1. Race-day surprise. Trying a new gel, ratio, or product in a key race. Practice every fueling element in training first.
2. Carb-loading the night before only. Glycogen super-compensation needs 24–48 hours, not 12.
3. Underfueling Zone 2 long sessions. Doing every long session depleted compromises the next day's quality.
4. Over-fueling easy sessions. Three gels on a 60-minute Zone 2 jog is unnecessary and trains your gut to expect calories that don't match output.
5. Ignoring fluid co-ingestion. Concentrated carbohydrate without water = osmotic diarrhea. Each 30 g gel needs 150–200 mL water.
6. High-fiber pre-race meals. Save the salad for after the race.
7. Treating 120 g/h as a status symbol. Most age-groupers perform worse at 120 g/h than at a well-tolerated 80 g/h.
8. Ignoring caffeine + carbohydrate synergy. Use both together; they boost intestinal absorption.
9. Bonking from chronic underfueling. Glycogen-depleted athletes feel fine for 60–90 min, then collapse. Start fueling before you feel low.

Also worth knowing: GI distress is the leading cause of DNF in long endurance events. Jeukendrup's landmark Ironman study reported 93% of triathletes experienced at least one GI symptom, 43% reported serious GI problems, and 7% abandoned the race due to GI issues.¹⁷ A "perfect" fueling plan that wrecks your gut is worse than a conservative one you can execute under pressure.

Bottom Line: Staged Recommendations

Tier 1 (all athletes, starting this week):

• Periodize daily intake: 3–5 g/kg on rest days, 5–7 g/kg on moderate days, 7–10 g/kg on long or hard days.
• Match in-session fueling to intensity and duration.
• Any session over 75 minutes with intensity: take in at least 30 g/h of carbohydrate.
• After hard or long sessions, hit 1.0–1.2 g/kg of carbohydrate within the first hour, with 20–30 g of protein.

Tier 2 (athletes targeting a peak event in 3–6 months):

• Start a structured gut-training block 8–10 weeks out. Add 10 g/h every 1–2 weeks during one weekly long session until you hit your race target.
• Switch to glucose+fructose products in a 2:1 ratio (or 1:0.8 if targeting > 90 g/h).
• Practice carbohydrate loading (8–12 g/kg/day) during a tune-up race 4–6 weeks out, not race week for the first time.
• Test the full fueling and hydration plan in 2–3 race-simulation sessions.

Tier 3 (highly trained athletes targeting long events > 4 h):

• Consider working up to 100–120 g/h, but only after Tier 2 is solid.
• Adopt 1:0.8 or 1:1 glucose:fructose at these doses.
• Reassess if the event is under 4 hours or run-dominant; the marginal benefit shrinks fast.

Stop pushing intake higher if any of these are true:

• GI symptoms are consistently 4/10 or worse.
• Race duration is under 90 minutes.
• The event is mostly Zone 2 relative to your fitness.
• Training has more low-intensity than high-intensity work.

The pros are not wrong about 120 g/h — they are just answering a different question than most readers of this post are asking. Hit your daily carbohydrate target, match in-race intake to intensity and duration, train your gut, recover with carbs first, and you will outperform athletes who chase the headline number without the foundation underneath it.

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References

Footnotes

1. Podlogar, T. Interview, Velo magazine (2024). Quoted on energy balance and 120 g/h performance evidence. ↩ ↩²

2. Ravikanti A, et al. "Effects of 60, 90, and 120 g/h carbohydrate intake on running economy in elite male marathoners." Journal of Applied Physiology 139(6):1581–1595 (November 2025). doi:10.1152/japplphysiol.00665.2025. ↩ ↩²

3. Carter JM, Jeukendrup AE, Jones DA. "The effect of carbohydrate mouth rinse on 1-h cycle time trial performance." Medicine & Science in Sports & Exercise 36(12):2107–2111 (2004). ↩

4. Wilson PB. "Carbohydrate intake of ≥ 100 g/h vs 60–90 g/h during endurance exercise: a narrative review." Sports Medicine 56(2):295–313 (online December 4, 2025). doi:10.1007/s40279-025-02372-6. ↩

5. Rothschild JA, Dudley-Rode H, Carpenter H, Smith ASM, Plews DJ, Maunder E. "Effects of carbohydrate ingestion on muscle glycogen utilization during endurance exercise: a meta-analysis." Journal of Applied Physiology 140(1):76–87 (January 1, 2026). doi:10.1152/japplphysiol.00861.2025. ↩

6. Jeukendrup A. "There is no optimal glucose:fructose ratio." MySportScience (https://www.mysportscience.com). ↩

7. Hearris MA, et al. "The effect of carbohydrate form on exogenous carbohydrate oxidation during prolonged exercise." Journal of Applied Physiology 132(6):1394–1406 (2022). ↩ ↩²

8. San Millán I, Brooks GA. "Assessment of metabolic flexibility by means of measuring blood lactate, fat, and carbohydrate oxidation responses to exercise in professional endurance athletes and less-fit individuals." Sports Medicine 48(2):467–479 (2018). ↩

9. Burke LM, Castell LM, Casa DJ, Close GL, et al. IOC Consensus Statement on Nutrition for Athletics. International Journal of Sport Nutrition and Exercise Metabolism (2019). ↩

10. Thomas DT, Erdman KA, Burke LM. "Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance." Medicine & Science in Sports & Exercise (2016). ↩

11. Burke LM, et al. "Crisis of confidence averted: Impairment of exercise economy and performance in elite race walkers by ketogenic low carbohydrate, high fat (LCHF) diet is reproducible." PLoS ONE 15(6):e0234027 (2020). ↩

12. Viribay A, et al. "Effects of 120 g/h of carbohydrate intake during a mountain marathon on exercise-induced muscle damage in elite runners." Nutrients 12(5):1367 (2020). ↩

13. Cox GR, et al. "Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling." Journal of Applied Physiology 109(1):126–134 (2010). ↩

14. McCubbin AJ, et al. Hydrogel sports drinks: independent evaluation. International Journal of Sport Nutrition and Exercise Metabolism and AIS race-walker trials. ↩

15. Rowe JT, et al. "Hydrogel carbohydrate-electrolyte beverage benefits at high concentration and intensity." Medicine & Science in Sports & Exercise (2021). ↩

16. van Hall G, Shirreffs SM, Calbet JAL. "Muscle glycogen resynthesis during recovery from cycle exercise: no effect of additional protein ingestion." Journal of Applied Physiology 88(5):1631–1636 (2000). ↩

17. Jeukendrup AE, et al. Ironman triathlon GI symptom incidence. Reported in de Oliveira EP, Burini RC, Jeukendrup A. "Gastrointestinal complaints during exercise: prevalence, etiology, and nutritional recommendations." Sports Medicine 44 Suppl 1:S79–85 (2014). ↩