High-Carb Fueling: How Many Carbs per Hour for a Marathon or Ultra?

What high-carb fueling actually means

High-carb fueling is the planned consumption of carbohydrate during prolonged exercise at an intake high enough to support blood glucose availability, provide an external fuel source and reduce the chance that energy availability becomes a decisive limiter. In practical endurance language, the expression usually describes intakes near the upper end of established recommendations, often 75–90 g/h. More recently, “ultra-high” strategies above 90 g/h, including 100–120 g/h, have attracted attention in cycling, triathlon, trail running and road racing.

The phrase should not be confused with eating as much sugar as possible. A successful plan coordinates dose, carbohydrate type, timing, concentration, fluid, intensity and intestinal tolerance. The target is not a heroic number on a spreadsheet. It is a repeatable delivery system that keeps working late in the race.

Why carbohydrate matters when the race gets long

Muscle and liver glycogen stores are limited. The body also oxidizes fat, especially at lower intensities, but carbohydrate remains particularly important when the pace is demanding, when hills require repeated surges, when the athlete accelerates late in the event or when fatigue makes a given speed relatively harder. As stored carbohydrate becomes less available, pace can fall, perceived effort can rise and concentration can deteriorate.

Carbohydrate consumed during exercise cannot completely refill working muscle glycogen in real time. It can, however, supply exogenous fuel and help maintain carbohydrate availability. This distinction explains why fueling early and regularly is generally more effective than waiting until the runner feels empty. Once the athlete has already slowed dramatically, a gel may help, but it cannot instantly reverse every process that produced the crisis.

Ingestion, absorption and oxidation are different

Ingestion is what enters the mouth. Absorption is what crosses the intestine. Exogenous carbohydrate oxidation is the use of ingested carbohydrate as fuel. These numbers are related, but they are not identical. Swallowing 120 g/h does not prove that all 120 grams will be absorbed or oxidized. A portion may remain in the gastrointestinal tract, particularly when the dose, concentration or intensity exceeds the athlete’s current capacity.

Increasing intake can increase exogenous oxidation, especially when glucose or maltodextrin is combined with fructose. Yet the dose-response curve is not infinitely linear. Moving from underfueling to an adequate 60–90 g/h may provide a larger practical gain than moving from a well-tolerated 90 to 120 g/h. More is only better when it solves a real problem without creating a new one.

The real target is usable energy, not empty wrappers

A fueling plan succeeds when it supports performance with acceptable symptoms and manageable logistics. If a runner consumes the planned number of gels but develops severe nausea, cannot drink enough fluid and slows at every aid station, the nominal carbohydrate target has failed. Conversely, an athlete who averages 72 rather than 80 g/h, feels energetic and finishes strongly may have executed an excellent plan.

How many carbohydrates per hour? A practical table

The ranges below are starting points, not medical prescriptions. Duration, intensity, training status, body size, race format, environmental conditions and individual tolerance all matter. Use them to identify the zone you should test, then personalize it in training.

Why hourly targets are usually not expressed per kilogram

Pre-race meals, daily carbohydrate availability and carbohydrate loading are commonly related to body mass. During exercise, however, conventional guidance has often used absolute grams per hour because intestinal transport capacity does not scale in a simple, perfectly linear way with body weight. A 55 kg runner does not automatically need half the hourly intake of a 110 kg runner.

Emerging research suggests that body size may influence the amount of exogenous carbohydrate an athlete can oxidize, so the future is likely to become more personalized. For now, body mass can inform the discussion, but it should not replace field testing. The most useful evidence remains the runner’s repeated response at target pace, in comparable heat, wearing the same equipment and using the same products.

Marathon vs ultramarathon: why one number does not fit both

A marathon and a 100-mile ultra can both benefit from 60–90 g/h, yet the reasons, constraints and delivery methods differ. Marathon fueling is usually compressed into a relatively stable period of high intensity. An ultra may last through major changes in temperature, terrain, appetite, pace and alertness. The hourly number therefore has to be interpreted inside the race.

The marathon: high demand, limited time to correct mistakes

A marathon runner operates at an intensity where carbohydrate oxidation is important and digestive comfort can be fragile. There is little time to pause, eat slowly or wait for the stomach to recover. The plan should therefore be simple: a small number of familiar products, an early start, predictable intervals and a clear relationship between concentrated gels and water.

Faster runners finish sooner but race at a higher absolute and relative intensity. Slower runners spend more time on course and may require more total carbohydrate, even if their hourly target is lower. This creates an important paradox: a four-and-a-half-hour runner taking 65 g/h consumes about 293 grams in total, while a two-and-a-half-hour runner at 90 g/h consumes about 225 grams. Total inventory should always be calculated from realistic finish time, not just target pace.

The ultra: lower hourly intensity, much greater duration

In ultrarunning, digestive sustainability often matters more than achieving an identical number every hour. A runner may manage 80 g/h during a cool opening section, reduce temporarily on a hot technical climb, then return to the target when the terrain becomes runnable. That is not failure; it is controlled adaptation. The danger lies in allowing a short reduction to become several hours of underfueling without noticing.

An ultra plan also needs flavor and texture rotation. Sweet gels that are effortless for three hours can become intolerable after ten. Savory rice, soft potatoes, bread, soup or another familiar food may improve compliance, but their carbohydrate content must still be counted. “Real food” is not automatically superior, and a salty taste does not guarantee meaningful carbohydrate or sodium.

The total-grams paradox

The hourly target is only one layer. Multiply it by expected duration to reveal the total logistical requirement. Ninety g/h for a three-hour marathon equals 270 grams. Seventy g/h for a ten-hour ultra equals 700 grams. Sixty-five g/h for a 24-hour event would theoretically equal 1,560 grams, although real ultra intake varies by phase. This calculation exposes whether the strategy is actually transportable, available at aid stations and tolerable.

Race fueling should be rehearsed within race-specific long runs and training blocks, not only during slow mileage. Pairing the plan with the final stages of hard endurance sessions shows whether it remains practical when breathing is heavier and coordination is fading. Your final taper should then protect the strategy you have already validated; our guide to the final two weeks before a race explains how to reduce training without creating last-minute nutritional experiments.

60, 90 or 120 grams per hour: what actually changes?

60 g/h: not a compromise, but a strong foundation

Sixty grams per hour sits near the traditional upper range associated with a single glucose-based delivery pathway. It is already equivalent to roughly two conventional 30-gram gels every hour, or one gel plus a substantial carbohydrate drink. For many recreational marathoners, reaching a consistent 60 g/h after previously taking 25 grams at irregular intervals is a meaningful performance upgrade.

This target is especially useful for athletes who are new to structured fueling, tend to develop gastrointestinal symptoms, expect a lower race intensity or cannot reliably carry more. It may also be appropriate during specific training sessions when the goal is to practice timing without reproducing the full race intake.

75–90 g/h: the established high-performance zone

For demanding endurance exercise beyond approximately 2.5–3 hours, 75–90 g/h is the best-supported high range. At these intakes, combining glucose or maltodextrin with fructose is normally preferable because the mixture uses more than one intestinal transport pathway. The dose should be divided across the hour rather than delivered as one large bolus.

Many athletes find 75 g/h easier to execute than 90 g/h while obtaining most of the practical benefit. Three 25-gram doses per hour, for example, create a simple 20-minute rhythm. The best number is not necessarily a multiple of the product in your pocket: an 80 g/h target might combine one 30-gram gel, 30 grams from drink and 20 grams from chews.

100–120 g/h: physiologically possible, not universally superior

Studies have demonstrated high exogenous carbohydrate oxidation when 120 g/h is supplied as fluid, gels, chews or mixed formats. A comparison of 120 versus 90 g/h also reported greater oxidation of ingested carbohydrate at the higher dose. However, greater oxidation did not provide additional sparing of endogenous carbohydrate in that study, and the research does not establish that every athlete will race faster at 120 g/h than at 90.

Very high intake can make sense in a narrow context: the race has exceptionally high carbohydrate demand; the athlete already tolerates and executes 90 g/h easily; a qualified sports dietitian is involved; products, ratios and fluid have been tested; and the extra dose creates no meaningful gastrointestinal, logistical or pacing cost. It should not be adopted merely because a professional cyclist or elite trail runner reported using it.

Glucose, maltodextrin and fructose: why the blend matters

Glucose and glucose polymers such as maltodextrin rely primarily on the intestinal transporter SGLT1. Fructose uses a different transporter, GLUT5. Combining the two can increase total carbohydrate absorption and exogenous oxidation compared with providing a very high dose from glucose alone. This is the logic behind “multiple transportable carbohydrates.”

Maltodextrin is a chain of glucose molecules. It can provide a large amount of carbohydrate with less sweetness and, depending on the formulation, lower osmolality than the same number of individual glucose molecules. It is not inherently faster or magically easier for everyone, but it is useful in concentrated endurance products. Sucrose also supplies both glucose and fructose after digestion and can contribute to a mixed-carbohydrate plan.

Is a 2:1 or 1:0.8 glucose-to-fructose ratio better?

The traditional 2:1 ratio reflects strategies such as 60 grams of glucose-based carbohydrate plus 30 grams of fructose per hour. Newer products often use ratios closer to 1:0.8, intended to support high oxidation at elevated total intakes and improve delivery. Both can work. The total dose, serving pattern, concentration and personal tolerance generally matter more than treating one exact ratio as universally perfect.

Read labels carefully. A front-of-pack claim such as “dual source” does not tell you the actual grams in each serving. Check total carbohydrate, serving size, suggested water volume, caffeine and sodium. If the manufacturer does not disclose the ratio, the product may still work, but your training response becomes even more important.

Does fructose always cause stomach problems?

No. Large amounts of isolated fructose can be difficult for some people, but fructose consumed with glucose during exercise is handled differently from a large isolated dose in daily life. Problems are more likely when total intake rises too quickly, the drink is overly concentrated, the athlete is dehydrated, intensity is excessive or the individual has a specific gastrointestinal sensitivity.

If symptoms repeatedly follow fructose-containing products, do not simply remove all carbohydrate. First compare dose, ratio, serving size, fluid, caffeine, fiber and effort. Persistent symptoms deserve assessment from a sports dietitian or clinician, particularly if they also occur outside exercise.

How to calculate carbs per hour and total race fuel

The plan becomes clearer when it is reduced to four calculations: hourly target, expected duration, carbohydrate per product and serving interval. Complete the arithmetic before buying fuel or filling a vest.

Example: a marathoner targeting 75 g/h with an expected time of 3 hours 40 minutes calculates 75 × 3.67 = approximately 275 grams. A small contingency may be useful, but carrying an unexplained 40% surplus creates weight and confusion.

If the athlete relied only on 25-gram gels, 275 ÷ 25 = 11 gels. That number may be physically possible but mentally unpleasant. Replacing part of it with a drink or chews can create variety while preserving the same hourly total.

Three doses each hour equal one dose every 20 minutes. Four smaller doses equal one every 15 minutes. A regular schedule usually produces a lower carbohydrate concentration in the stomach at any single moment than taking the entire hourly target at once.

A worked 80 g/h example

Calculate logistics before perfecting physiology

Write down how many grams are carried at the start, how many are collected from each aid station and where water is available. Note which products contain caffeine. If you use a concentrated flask, mark the volume corresponding to each hourly dose. A theoretically elegant plan is useless if one bottle contains four hours of fuel and the runner accidentally drinks half of it in the first 30 minutes.

Use ranges when the finish time is uncertain. A marathon goal of 3:45 might include a plan for 3:30–4:00. An ultra plan should be built around race sections rather than a single optimistic finish prediction. Carry enough to survive a delayed aid station, but avoid turning every pocket into an unlabeled emergency supply.

How to build a high-carb marathon fueling plan

A marathon plan should feel almost boring by race morning. The products, timing, breakfast and water strategy have already been rehearsed. Race day is the final execution, not the first complete experiment.

Three example marathon plans

These examples demonstrate structure rather than prescribe brands or exact quantities. Product labels vary, so calculate the actual carbohydrate in your chosen items.

The faster example does not mean every sub-three-hour runner needs 90 g/h, and the slower example does not mean slower athletes should fuel less aggressively. The table shows how intensity, time and total inventory interact. Test the lower end first, then increase if it is useful and repeatable.

Carbohydrate loading and race breakfast

During the taper, training volume falls but carbohydrate availability should not collapse. A traditional carbohydrate-loading strategy for a marathon may reach approximately 10–12 g/kg/day during the final 36–48 hours, but that intake is demanding and should be planned with familiar, lower-fiber foods rather than improvised at the pasta party. A more individual approach may be appropriate, especially for runners with gastrointestinal conditions or specific dietary needs.

A common pre-exercise framework is 1–4 g/kg of carbohydrate one to four hours before the start, with the amount increasing as more digestion time is available. Again, familiarity matters. If you want a complete meal-by-meal framework, read our guide to what to eat before a race. Do not use breakfast to compensate for a poor week of eating, and do not begin the marathon feeling uncomfortably full.

High-carb fueling for an ultramarathon: build a plan that survives the hours

An ultra strategy should remain functional when the weather changes, a climb takes longer than expected, sweet flavors become tiring or the runner reaches an aid station with a slightly unsettled stomach. The target needs structure, but the structure needs flexibility.

Divide the race into phases

A useful model is opening, settled middle, difficult phase and final section. Early in the race, protect the stomach from excessive excitement: eat on schedule, keep intensity controlled and avoid sampling every aid-station food. During the middle, maintain the plan and monitor drift. In a difficult phase, reduce serving size or concentration rather than abandoning all intake. In the final hours, use the most tolerable sources and deploy caffeine only according to the tested plan.

Use modular hourly building blocks

Instead of packing “food for 12 hours,” create repeatable modules. An 80-gram module might include 30 grams from drink, a 25-gram gel and 25 grams from chews or a soft solid. A 65-gram low-sweetness module might combine a neutral drink, rice and a small gel. Colour-code caffeinated and non-caffeinated options. Modules make missing intake visible and allow crew members to help without guessing.

Practical ranges for 50 km, 100 km and 100 miles

These are test ranges, not rigid rules. A highly trained 100-mile athlete may sustain 90 g/h. Another may perform best around 65–70 g/h with excellent fluid control and no long gaps. The longer the event, the more important the average and consistency become relative to any single perfect hour.

Do ultra runners need protein and fat during the race?

Small amounts can provide variety, satiety and additional energy in very long events. They are not a replacement for carbohydrate, and large portions can slow gastric emptying or create heaviness. Protein is not a magic anti-fatigue supplement during an ultra. If you use sandwiches, cheese, nut butter or other mixed foods, count their carbohydrate contribution separately and test them during long training sessions.

Solid food is useful, not compulsory

There is no rule that an ultra runner must eat “real food.” If sports products remain tolerable and practical, they can supply the target. If sweetness becomes a barrier after eight hours, familiar solid food may restore continuity. Choose textures that are easy to chew while moving and avoid foods that become unappealing in heat or cold.

Race planning extends beyond nutrition. Our guide on how to prepare for an ultra-trail race connects fueling practice with terrain, equipment, pacing and aid-station strategy.

Gels, drinks, chews and food: how to reach the target without confusion

Energy gels

Gels are compact, measurable and easy to carry. A conventional gel may provide 20–30 grams of carbohydrate, while larger products may provide more. Some require water; isotonic-style gels may be less concentrated. Caffeine content can range widely. Never count “one gel” as a universal unit—count the carbohydrate and caffeine on the label.

Carbohydrate drinks

Drinks can distribute carbohydrate across the hour and reduce chewing. The limitation is that thirst and energy requirements do not always move together. In heat, drinking more of a fixed high-carbohydrate mixture may deliver too much energy and create an excessive concentration. In cool conditions, drinking enough to reach the carb target may force unnecessary fluid. A concentrated fuel bottle plus separate water is one solution, but it demands clear markings and disciplined sipping.

Chews and blocks

Chews allow small doses and can be easier to manage than opening a gel every 20 minutes. Their texture may become firm in cold weather or sticky in heat. Count pieces before the race and calculate carbohydrate per piece. “One packet per hour” only works if the packet contains the required amount.

Everyday foods

Bananas, rice cakes, jam sandwiches, soft potatoes, pretzels and sweets can contribute. Their strengths are familiarity, variety and cost. Their limitations include variable portion size, fiber, fat, chewing and storage. A banana from an aid station may be half, one-third or a whole fruit. Estimate conservatively and use ordinary food as a defined part of the plan rather than an uncounted bonus.

Four ways to construct approximately 90 g/h

Use the combination that remains clear when tired. A complex plan with seven flavors may look premium on the kitchen table but create decision fatigue after four hours. Label products, group them by race phase and keep the core arithmetic simple.

Gut training: how to prepare for high-carb fueling

The gastrointestinal system is trainable. Repeated exposure to carbohydrate and fluid during exercise can improve tolerance, increase comfort with stomach volume and help the athlete refine practical behavior. Gut training also teaches non-physiological skills: opening packets at pace, drinking without gulping air, carrying fuel and noticing early symptoms.

Adaptation is specific. Tolerating 90 g/h while cycling gently does not guarantee tolerance while running at marathon pace, because running adds mechanical impact and may place a greater strain on the gastrointestinal system. Practice in the sport, intensity, climate and body position that resemble the target event.

An eight-week gut-training progression

One specific exposure every seven to ten days is a practical pattern for many runners, with lower or no intake during sessions that do not require race fueling. Some athletes adapt more quickly; others need a longer block. Increase only one important variable at a time. If you simultaneously change product, fructose ratio, fluid, caffeine and dose, you will not know which change caused an improvement or a problem.

What does “tolerated” mean?

Tolerance is not simply the absence of vomiting. A useful dose produces no more than mild, transient symptoms; allows the planned intensity; does not create urgent bathroom stops; remains acceptable late in the session; and does not cause prolonged nausea afterwards. Record symptom severity on a simple zero-to-ten scale. A recurring score of five that the athlete “pushes through” is not successful gut training.

Do you need 90 g/h in every long run?

No. Use full race fueling in selected sessions that have a clear rehearsal objective. Other easy runs may require less, depending on duration, previous meals and training goal. Chronic underfueling is not a badge of endurance, but neither is maximal race intake required in every workout. Separate sessions designed to train the race plan from sessions with a different nutritional purpose.

If you sometimes train before breakfast, keep that decision distinct from marathon preparation. Our guide to running, food choices and glycemic index provides additional context for matching carbohydrate availability to the session.

Carbohydrate, water and sodium: connected but separate plans

Carbohydrate, fluid and sodium interact in the bottle and in the gut, but each should be calculated for its own purpose. Your carbohydrate target reflects energy strategy. Your fluid plan reflects sweat losses, conditions, thirst, access and tolerance. Sodium strategy reflects sweat composition, diet, event duration and the products you use. A single “all-in-one” number cannot solve all three.

Drink concentration matters

A drink containing 60 grams of carbohydrate in 500 ml has a 12% carbohydrate concentration. The same 60 grams in 750 ml is 8%. A more concentrated solution is not automatically wrong, especially when used as a fuel concentrate with separate water, but it changes gastric and intestinal demands. Measure powder and bottle volume instead of estimating with an unlevel scoop.

Avoid both major dehydration and overdrinking

Substantial dehydration can raise cardiovascular strain, perceived effort and gastrointestinal stress. Drinking far beyond losses can also be dangerous because it increases the risk of exercise-associated hyponatraemia, especially in long events. “Drink as much as possible” is not a safe endurance strategy. Use training sweat-rate observations, body-mass changes, thirst, weather and professional guidance to create a sensible range.

A pre/post training body-mass check can estimate net fluid loss, but it is not a perfect race prescription because drinking, urination and substrate use affect the calculation. Repeat it in different conditions. Never attempt to finish a long race heavier because of forced fluid intake.

Sodium is not a universal treatment for nausea or cramps

Sodium replacement can be useful in long, hot events and for athletes with high sweat sodium losses, but more sodium does not automatically cure muscle cramps, nausea or fatigue. Count sodium from drinks, gels, capsules and aid-station foods. Taking salt capsules without fluid or without knowing the total dose can worsen thirst and gastrointestinal discomfort.

Nausea, bloating, cramps and diarrhea: how to interpret the signals

Gastrointestinal symptoms are common in endurance racing, especially in ultras. They rarely have one cause. Intensity, running impact, reduced gut blood flow, heat, dehydration, anxiety, caffeine, medication, fiber, fat, carbohydrate dose and drink concentration can all contribute. “Eat less” may be correct in one situation and entirely wrong in another.

Fullness and slow gastric emptying

Temporarily reduce intensity, switch to small sips and check whether the drink is overly concentrated. Do not swallow a large catch-up dose. Steep climbing and heat can make gastric emptying more difficult. A short stabilisation period should not automatically become two hours without energy; as symptoms ease, restart with small, diluted and familiar servings.

Sweetness fatigue

Rotate flavor and texture before complete aversion develops. Less-sweet products, neutral drinks, small savory foods and rinsing the mouth with water may help. Remember that savory is a sensory category, not a nutrient amount. A cup of broth may feel excellent but does not necessarily replace 30 grams of carbohydrate.

Abdominal cramps and urgency

Review dose per serving, total fructose, caffeine, fiber, sugar alcohols and the previous meal. Some sugar-free sweets and ordinary foods contain polyols that can have a laxative effect. Avoid using non-steroidal anti-inflammatory drugs as a preventive solution; during ultra-endurance events they can increase gastrointestinal and kidney risks.

When pace is the hidden cause

A plan tolerated at easy pace can fail when the athlete starts too hard. Higher intensity reduces digestive margin while increasing carbohydrate demand. Marathon runners can therefore create a double crisis: rapid glycogen use plus a stomach that becomes less able to accept fuel. Gut training needs at least some exposure to realistic race intensity.

A race-day reset protocol

The 12 most common high-carb fueling mistakes

1. Copying 120 g/h from a professional athlete

The professional has different power output, energy expenditure, training history, product support and often expert supervision. Copy the method of testing, not the final headline number.

2. Counting packet weight instead of carbohydrate

A 45-gram sachet does not necessarily contain 45 grams of carbohydrate. Read whether the nutrition panel refers to 100 grams, one serving or the entire pack.

3. Waiting for hunger

Hunger is late and unreliable during a marathon. Begin according to schedule, generally within the first half hour, and use small regular doses.

4. Consuming every missed dose at once

If you miss 25 grams, do not automatically add it to the next full serving. Recover gradually or accept a slightly lower average. A sudden concentrated bolus may create the problem you were trying to avoid.

5. Testing only on slow long runs

The gut must experience race-specific intensity. Include fueling in sessions with marathon-pace blocks, sustained climbs or technical terrain that resembles the event.

6. Using a concentrated fuel bottle as thirst fluid

A concentrate is liquid food. Drinking it for thirst may deliver too many carbs; saving it only for energy may leave you underhydrated. Separate and label the functions.

7. Guessing aid-station portions

A cup may contain 100 or 200 ml, and the sports drink may be mixed at a different strength. Treat race-supplied fuel as verified only after checking the organizer’s information and testing the product.

8. Forgetting total caffeine

Caffeine may support alertness and performance, but excessive intake can increase nausea, agitation, perceived heart rate and post-race sleep problems. Add caffeine from gels, drink, coffee, cola and tablets.

9. Changing breakfast, product and dose together

If symptoms appear, you will not know the cause. The target race should confirm a system, not introduce five new variables.

10. Confusing calories with carbohydrate

A high-fat bar can contain substantial energy but relatively little rapidly available carbohydrate. It may have a role in a long ultra, but it does not automatically satisfy the g/h target.

11. Ignoring oral health

Repeated exposure to sugars and acidic drinks can affect dental health. When practical, rinse with water, avoid brushing immediately after highly acidic drinks, and maintain normal dental hygiene. This is a reason to manage necessary race fuel intelligently, not to underfuel.

12. Treating the plan as unchangeable

Heat, delay, nausea or a lost bottle require adaptation. A strong plan defines priorities and substitutions. Rigidity is fragile; structured flexibility is robust.

Checklist: from the first test to race day

Six to eight weeks before

• Define the most realistic race-duration range.
• Measure your current intake in g/h during long sessions.
• Choose multiple transportable carbohydrates if the target exceeds about 60 g/h.
• Increase by roughly 10–15 g/h at a time when needed.
• Test product, serving rhythm, fluid, caffeine and carrying method.
• Record symptoms during the run and for several hours afterwards.

Two to three weeks before

• Complete a dress rehearsal with race intake, pace, breakfast and equipment.
• Verify official products and aid-station locations.
• Calculate total grams, product count and a small reserve.
• Create a plan B for a lost gel, heat, nausea or delay.
• Do not chase a new carbohydrate record in the final long run.

The day before

• Distribute carbohydrate across meals instead of concentrating everything at dinner.
• Reduce unusually high-fiber, high-fat or unfamiliar foods if you are sensitive.
• Arrange gels and bottles in chronological order.
• Mark caffeinated products and check labels one last time.
• Do not force food and water far beyond the plan because you fear being “empty.”

During the race

• Start early and use small, regular servings.
• Review the total each hour or race block, not every minute.
• Adjust fluid to the conditions without accidentally destroying the energy target.
• If mild nausea appears, reduce intensity and concentration before abandoning all fuel.
• Never consume all missed doses in one catch-up bolus.
• Stop and seek assistance for severe symptoms.

After the event, record what you actually consumed. Compare plan, real dose, pace, energy and symptoms. Do not rely on memory alone. When the next priority becomes recovery, use our guide to active recovery after long runs and trail races to decide between rest, walking and genuinely easy running.

How to choose your personal number

Your best target sits at the intersection of four factors: race energy demand, scientific evidence, trained intestinal capacity and logistical simplicity. If one is missing, the plan is incomplete. An athlete may need substantial carbohydrate and tolerate 90 g/h but be unable to carry the products. Another may carry everything yet never have tested the dose at race pace.

For many recreational runners, the most successful progression looks less dramatic than social media suggests: move from irregular 30–40 g/h to a reliable 60, then towards 70–75 g/h if the event and tolerance justify it. That improvement can be more valuable than occasionally reaching 120. Basic precision beats sporadic extremism.

Related running guides

Fueling works best inside a coherent preparation plan. These guides connect nutrition with race readiness, ultra planning, recovery and sleep.