11 Fueling, Electrolytes, and Pacing Tips to Prevent Bonking on Long Runs

Long runs are won with planning, not just grit. To prevent bonking—the sudden energy crash that derails pace and decision-making—set a simple fueling strategy, match electrolytes to your sweat, and pace conservatively early. Start fueling within 30 minutes, aim for steady carbs each hour, sip fluids on a schedule, and target a slight negative split so your energy curve trends upward. Use practical, practiced choices you’ve tested: gels or real food, tablets or mixes, and watch alerts to execute. The tips below turn that plan into a repeatable routine for training and race day.

HikingManual

This Hiking Manual guide delivers trail-tested fueling, electrolytes for runners, and pacing practices that work for road and trail efforts lasting 90+ minutes. We prioritize safety, value, and simplicity—whether you prefer gels, chews, carb drink mixes, or real-food options—so you can build a hydration plan and fueling strategy you trust. We favor clear, repeatable steps you can rehearse in training and use on race day.

Bonking is a rapid drop in available energy during prolonged exercise due to glycogen depletion, underfueling, inadequate electrolytes, or overheating. It shows up as heavy legs, dizziness, irritability, and fading pace, and it matters for both safety on technical trails and performance on the road. The fix: consistent carbohydrates, sodium per hour matched to sweat, and controlled pacing.

Understand carb needs per hour

Carbohydrates during exercise maintain blood glucose and replenish working muscle, delaying fatigue and improving performance. Evidence summaries support ingesting carbs as efforts extend, with classic guidance of 30–60 g per hour and clear benefits for endurance performance when taken consistently during exercise evidence on carbohydrate intake and performance. Well-trained athletes have pushed higher by using blends of sugars that absorb via different transporters, with some tolerating up to 90–120 g per hour when practiced nutrition and endurance performance guidance.

Step up to the right target based on duration, intensity, and gut comfort:

Definition (quotable): Multiple transportable carbohydrates are blends of glucose and fructose that use different intestinal transporters to increase total carb absorption during exercise, allowing higher intakes (up to 90–120 g/h in some athletes) with less gut distress and better performance when practiced.

Start fueling early and stay consistent

Start fueling within the first 30 minutes, then stay on a timer so energy never dips and the gut stays calm. A simple rhythm: one gel every 35 minutes, or 200–250 ml of a carb drink every 20 minutes, adjusting to hit your grams-per-hour goal as intensity increases marathon training fuel timing.

Use watch or phone alerts to avoid missed feeds, especially in races or group runs when focus drifts.

Mini checklist:

• Pack enough units to hit your target grams per hour
• Pre-open wrappers and stage feeds in easy-to-reach pockets or a vest
• Alternate gel and drink to meet hydration goals simultaneously

Match sodium intake to your sweat rate

Sweat sodium losses vary widely—from roughly 115 to 2000 mg per liter—and hourly losses can range from ~200 to 1500 mg depending on sweat rate and conditions. That’s why electrolyte plans must be personalized and practiced. A practical starting point for longer efforts is 700–900 mg sodium per hour, then adjust for heat, humidity, pace, and visible salt on clothes or skin. Most electrolyte tablets or drink mixes provide 250–300 mg per serving; combine servings to match your hourly target. Personalize and rehearse your plan well before race day so your gut and taste preferences align under effort. Hiking Manual favors a clear starting range and dialing it in with training logs and feedback.

Definition (quotable): Electrolytes (sodium, potassium, chloride, etc.) are charged minerals that regulate fluid balance, nerve impulses, and muscle contractions during exercise. Replacing sweat losses supports blood volume, prevents cramps, and maintains performance in prolonged efforts.

Hydrate with a plan

When runs exceed 90 minutes, intensity is high, or heat is a factor, rely on planned drinking—thirst can lag behind needs. Performance declines around 2% body mass loss from dehydration, so aim to stay ahead with small, regular intakes Gatorade Sports Science Institute review on planned drinking. A practical cadence is 3–4 long sips every 15 minutes using bottles or soft flasks; adding electrolytes helps fluid retention and palatability Korey Stringer Institute hydration guide. Cool, lightly flavored beverages and modest caffeine are acceptable and do not promote diuresis during exercise NATA fluid replacement statement.

Carb load smartly before long efforts

Carb loading is broader than a single pasta dinner. Over 1–3 days, emphasize easy-to-digest carbs like oatmeal, rice, potatoes, pancakes, fruit, and low-fiber breads while keeping protein normal and fats moderate. Reduce fiber gradually and go low-fiber only in the final 24 hours to minimize GI distress practical carb-loading primer. Add salted fluids to support sodium.

A simple 2-day outline:

• Breakfasts: oatmeal with banana and honey; pancakes with maple syrup; add a little yogurt or eggs for protein
• Lunches: rice bowls with lean protein; sandwiches on low-fiber bread; broth or miso for extra sodium
• Snacks: pretzels, rice cakes with jam, fruit smoothies
• Dinners: potatoes or rice with lean protein and a small portion of low-fiber veg; sports drink or electrolyte mix with meals

Simple carbs deliver quick energy; complex carbs provide steadier energy over long durations evidence on carbohydrate intake and performance.

Train your gut in practice runs

Gut comfort is trainable. Start around 40–60 g carbs per hour on long runs and gradually increase toward your target across several weeks. Practice fluid and sodium timing simultaneously, log what you ate, how much, and how it felt, and adjust textures (gels, chews, liquids, soft solids) and intervals to reduce GI distress. Choose a conservative pacing day when testing new fueling so results aren’t skewed by intensity spikes.

Pace with intention using negative splits

A negative split means running the second half slightly faster than the first, conserving glycogen early so fueling keeps up with demand. Blueprint: run 3–5% easier than goal pace for the first third, settle into goal pace mid-race, then finish strong. Tie feeding windows to mile or kilometer markers—e.g., gel at 6, 12, 18 miles—so you don’t skip feeds when the watch buzz gets lost in the noise. A conservative start also makes it easier to test and refine nutrition in training.

Avoid underfueling on training days and race day

Underfueling is common in endurance sports—don’t leave it to chance. Write your plan and pre-pack totals per hour for carbs, sodium, and fluid. Before you leave, run a quick audit:

• Carbs (g/h)?
• Sodium (mg/h)?
• Fluid (ml/h)?
• Timers set?

Intervene early if you notice rising effort at a steady pace, lightheadedness, or irritability—take carbs and sodium sooner.

Use tech to automate fueling and hydration reminders

Program your watch: fuel every 30–40 minutes, sip every 15 minutes, and do an hourly sodium check. GPS watches, phone timers, or app-based cues work well in races. After each long run, log total carbs, sodium, fluid, conditions, and GI comfort to refine week over week. On trails, tie reminders to landmarks (major junctions, summits) in case GPS alerts vary under canopy; offline maps and breadcrumb features help you keep focus on execution.

Test different carb sources and textures

Experiment until you find a mix that meets your grams-per-hour target without GI blowback. Combining glucose and fructose can improve absorption and performance when tolerated.

Rotation strategy:

• Alternate flavors and textures to avoid palate fatigue
• Lean on liquid calories in heat when chewing feels hard
• Use real-food bites (e.g., rice bars) during easier segments

Quick pros/cons:

• Gels: compact and fast; can feel overly sweet without water
• Drink mix: hydrates and fuels together; requires measuring and carrying fluid
• Chews: bite-sized control; slower to eat when breathing hard
• Soft solids (bananas, rice bars): familiar taste/texture; bulkier to carry

Prioritize recovery nutrition and rehydration

Refuel within two hours post-run with fluids, electrolytes, carbohydrates, and protein. A simple formula: 20–30 g protein plus 1–1.2 g/kg body mass of carbs and salty fluids. Fluids containing carbs and electrolytes support both rehydration and glycogen replenishment; cool, flavored drinks are often better tolerated after hard efforts NATA fluid replacement statement.

Easy options:

• Smoothie with milk or yogurt, fruit, oats, a pinch of salt
• Broth plus rice and eggs, followed by a sports drink
• Sandwich and pretzels, plus an electrolyte mix

Frequently asked questions

What does bonking mean in running and what causes it?

Bonking is a sudden energy crash during prolonged exercise caused by depleted glycogen and inadequate fueling or electrolytes. Hiking Manual’s approach—steady carbs, sodium, and hydration—helps prevent it.

How many grams of carbs per hour should I take on long runs?

Most runners do well starting at 30–60 g/h and building toward 60–90 g/h as tolerated. Hiking Manual recommends practicing higher intakes (up to 120 g/h with glucose+fructose blends) only after gut training.

How much sodium and fluid do I need per hour?

A practical starting point is 700–900 mg sodium per hour and small, regular sips of fluid every 10–15 minutes. Hiking Manual recommends adjusting to your sweat rate, heat, and duration during long-run practice.

When should I start taking fuel if I feel fine early in a run?

Start within the first 30 minutes and stick to a timer every 30–40 minutes. Hiking Manual emphasizes early, steady fueling to keep blood glucose up.

What pacing strategy best prevents bonking?

Use a conservative start and aim for a slight negative split. Hiking Manual pairs that pacing with planned feeds so execution stays on track.

• Sports-Nutrition
• Fueling-Strategies
• Long-Runs
• Electrolytes
• Running-Tips
• Pacing-Techniques
• Bonking-Prevention