What to Eat Before a Long Run or Ride: A Fuelling Guide for Endurance Athletes

Why pre-session fuelling is non-negotiable for long efforts

Muscle glycogen is the currency of endurance performance. You store roughly 400-500 g of it in a trained state, which buys you 90-120 minutes of moderate-intensity work before the tank starts to run dry. For anything over that window, what you eat beforehand directly shapes how the session feels and what adaptations you actually lock in.

Turn up under-fuelled to a three-hour ride or a 30 km long run and you get the same session on paper, very different session in the body. Pace drifts down in the last third. Heart rate drifts up. Perceived effort climbs. The training stress you meant to apply to the aerobic system gets muddied by stress-hormone responses to low energy availability. Adaptation suffers. Recovery takes longer.

This is why serious endurance athletes treat fuelling as programming, not an afterthought.

The timing windows that matter

Food has to clear the stomach before it is useful. Gastric emptying rates, blood flow diverted to working muscles, and your own gut training all interact. Three practical windows:

• 3-4 hours out. Large meal window. Stomach can handle a full plate. Aim for 1-4 g/kg of carbohydrate, modest protein, low fat, low fibre. This is the pre-run breakfast window for marathon training sessions and the pre-ride meal for long weekend rides.
• 60-90 minutes out. Medium snack. Stomach is still settling. Think a banana and a slice of toast with honey, or a small bowl of rice. Keep it to around 1 g/kg.
• 15-30 minutes out. Top-up window only. A gel, a piece of fruit, a small sports drink. You are not loading glycogen here, you are keeping blood glucose stable so the first 30 minutes of the session feels smooth.

The mistake most hobbyists make is trying to fuel a long session in the 45-90 minute window with a full meal. That is too close for solids, too far for a gel. Either shift earlier and eat properly, or shift later and go small.

How many carbs is enough

The sports nutrition literature converges on 1-4 g of carbohydrate per kilogram of bodyweight in the hours before endurance exercise. Where you sit in that range depends on session length, intensity, and how close to the start you are eating.

• 70 kg athlete, 3 hours before a 2-hour long run: 2-3 g/kg, so 140-210 g of carbs. A big bowl of oats with banana, honey, and milk gets you there.
• 70 kg athlete, 45 minutes before an easy hour: 0.5-1 g/kg, so 35-70 g. A banana and a piece of toast with jam.
• 70 kg athlete, 30 minutes before a marathon: 0.5 g/kg in liquid form, so a gel plus 300 ml of sports drink.

Above 4 g/kg you get diminishing returns and rising GI risk. Below 1 g/kg for a session over 90 minutes and you are asking your body to dip into glycogen it did not have time to top up.

Glycaemic index, gels, and the 30-minute trap

Older guidance pushed low-GI carbs before a session to avoid a rebound hypoglycaemia effect. Current evidence is that for well-trained athletes the rebound rarely matters once exercise starts, because the demand for glucose overwhelms the insulin response within minutes. If white rice or a gel digests better for you than oats, use it.

The one timing trap worth naming: eating a large, fast-absorbing carb load 20-45 minutes before the start can leave you catching a blood-glucose dip right as you begin. Either push the carbs earlier (3+ hours) or closer (under 15 minutes). The dead zone in the middle is where people feel flat in the first kilometre.

Liquid versus solid

Solids carry more calories per mouthful and keep you fuller longer, which matters on a four-hour ride. Liquids empty from the stomach faster and reduce GI risk, which matters when the session is close or the nerves are high.

Practical rule:

• More than 2 hours out: solid food, real meal.
• 1-2 hours out: semi-solid or smaller solids. Smoothies, toast, fruit.
• Under 60 minutes: liquid or gel only.

On race morning, stick with what you have trained. A new product 30 minutes before a marathon is a gamble nobody needs.

Fuelled versus fasted: what each session actually needs

Fasted training has a place. For easy aerobic work under about 75 minutes, training with low carb availability can push mitochondrial density and fat oxidation gains. Zone 2 sessions, easy shakeouts, and recovery rides are reasonable candidates.

Fasted is the wrong choice for:

• Long runs or rides over 90 minutes. You will bonk or limp home, neither of which produces the adaptation you wanted.
• Quality sessions: intervals, threshold, hills. Carbs are the fuel for high-intensity work. Running an interval session on empty turns it into a survival exercise.
• Race-simulation sessions. If the race is fuelled, train fuelled.
• Back-to-back hard days. Recovery suffers when glycogen never refills.

Distinguishing which session is which is the core of periodised fuelling. The Zone 2 research guide covers why low-intensity work is the place where fasted protocols earn their keep.

What to avoid

• High fat. Slows gastric emptying. A bacon-and-eggs breakfast three hours before a long ride sits in your stomach for the first hour.
• High fibre. Move the bran muffin and the apple skins to the recovery meal.
• Novelty. Race morning is not the day to try a new gel brand, a new coffee, or a new breakfast cereal.
• Alcohol the night before. Dehydrates you, disrupts sleep, impairs glycogen storage.
• Under-eating. The most common mistake. Skipping breakfast before a 20 km run because you are running late turns a training session into damage.

How Pelaris fits in

Pelaris does not replace the work of learning your own gut. It gives you a coaching layer that makes fuelling decisions session-specific instead of generic.

Session-aware coaching prompts. When your week has a long run on Sunday, the AI coach in the app can prompt fuelling guidance calibrated to that session: the window you are in, the intensity planned, and the duration. A Tuesday Zone 2 easy hour gets different advice than a Saturday 100 km ride.

Engine Room surfaces fuel content by phase. The Engine Room pulls fuel-category guides, recipes, and routines based on where you are in your training block. Base phase surfaces volume-ready carb strategies. Peak and race-prep phases surface race-day protocols, gel timing, and carb loading. It is the same taxonomy you see in this guide, organised around your current periodisation.

Strava data informs the feedback loop. Connect Strava and every completed session flows in with pace, power, heart rate, and duration. When you log how a session felt after a given fuelling approach, the coach has concrete data to work from. Over weeks it sharpens what “enough” looks like for your body, not a textbook body.

Logged sessions, logged context. The workout tracker keeps a record of the fuelling approach alongside the session outcome. This is the raw material that turns guesswork into a repeatable pre-session routine. Our methodology explains why we built that feedback loop before we built anything flashier.

The habit worth building

Write down what you eat before your best session. Repeat it before the next one of the same type. Adjust one variable at a time. The athletes who fuel well are not the ones who read the most research; they are the ones who kept notes, trained their gut, and built a repeatable protocol before race day arrived. Pelaris helps you keep those notes in one place and connect them to the session they actually served.