How to Practise Your Race-Day Nutrition During Long Runs

You Already Know You Need a Fueling Plan. The Problem Is You've Never Tested It.

You've mapped out your gel schedule. You know roughly how many carbs per hour you need. You might even have a spreadsheet.

But here's the question most runners never ask themselves: have you actually practised it at race pace, on tired legs, in the conditions you'll face on the day?

A 2024 study in Sports Medicine — Open found that energy gels had the highest "leftover rate" of any fuel format during marathons. Runners packed them and then didn't take them. The gap between planning and executing is where race-day nutrition falls apart.

This guide gives you a concrete 8-week protocol for testing and refining your race nutrition during training — so that by race morning, your fueling plan is second nature.

Why Practice Matters More Than the Perfect Plan

Your gut is trainable. That's the single most important fact in race-day nutrition.

The enzymes that absorb carbohydrates during exercise, the gastric emptying rate that determines how fast fuel leaves your stomach, the intestinal transporters that move glucose and fructose into your bloodstream — all of these adapt to repeated stimulus.

If you never fuel during training runs, your gut isn't ready to process 60–90 grams of carbs per hour on race day. It doesn't matter how perfect your plan looks on paper. Your stomach will reject it.

Research consistently shows that athletes who practise their nutrition strategy in training report fewer GI issues on race day. Not because they found the "right" gel — because they trained their gut to handle fueling under stress.

The 8-Week Race Nutrition Practice Protocol

This protocol assumes your race is 8 weeks away. If you have more time, extend the early phases. If you have less, compress Weeks 1–3 but never skip the race simulations.

Weeks 1–2: Baseline and Introduction

Goal: Find your starting point and introduce mid-run fueling if you haven't before.

On your longest run each week:

• Take a single gel or fuel source at the 45-minute mark
• Drink 150–200ml of water with it
• Note how your stomach responds over the next 30 minutes

If you've never fueled during training, this is about proving to your gut that food is coming. Don't worry about hitting carb targets yet. Start with one intake and see how it goes.

What to track: Did you feel bloated? Nauseous? Fine? How long before the fuel felt like it was "working"? Write it down — you'll forget otherwise.

Weeks 3–4: Build Volume and Find Your Products

Goal: Increase to two or three fuel intakes per long run and start testing the specific products you'll use on race day.

On your longest run each week:

• Take your first fuel at 30–40 minutes
• Take a second fuel 25–30 minutes later
• If the run is long enough, take a third
• Aim for 30–45 grams of carbs per hour

This is when you test specific products. If your race provides a particular sports drink or gel on course, get hold of it now. Don't assume you'll tolerate it just because you've used something similar.

Key rule: Only change one variable at a time. Don't switch gels AND change your hydration AND try a new timing pattern in the same run.

Weeks 5–6: Hit Race-Day Targets

Goal: Match your planned race-day carb and fluid intake during long runs.

On your longest run each week:

• Fuel every 20–30 minutes
• Target 60–90 grams of carbs per hour (the range depends on your body weight, pace, and what your gut can handle)
• Practise your planned hydration alongside your fueling — if you'll carry a bottle, carry it now; if you'll rely on aid stations, simulate the stop-start

This is where most runners discover problems. The gel that was fine at 30g/hour causes cramping at 60g/hour. The sports drink you love at rest tastes revolting at tempo pace. Better to find out now.

How Sweatr helps: Sweatr calculates your personal carb and fluid targets per hour based on your body weight, sweat rate, and training data from your Apple Watch or Garmin. Instead of guessing at "60–90 grams," you get a specific number tailored to you — and a plan that maps those numbers to real products.

Weeks 7–8: Full Race Simulation

Goal: Run your final long runs as complete dress rehearsals.

On your last two long runs before taper:

• Eat the same pre-run breakfast you'll eat on race morning, at the same time gap before you start
• Carry exactly the fuel you'll carry on race day
• Follow your fueling plan to the letter — same products, same timing, same fluid intake
• Run at or near race pace for at least the second half

The goal isn't a hard workout. It's a systems check. You want to finish these runs knowing that your nutrition plan works when everything else is also happening — pace pressure, heat, fatigue, nerves.

If something goes wrong, you still have time to adjust. If nothing goes wrong, you've just earned a massive confidence boost for race morning.

What to Do When Something Doesn't Work

It will happen. A gel will make your stomach turn at mile 14. You'll feel bloated after your third fuel intake. Here's how to troubleshoot.

Problem: Nausea after taking gels

Likely cause: Too much fuel in the stomach at once, or taking a conventional gel without enough water.

Fix: Switch to smaller, more frequent intakes. If you're taking one gel every 30 minutes, try half a gel every 15 minutes instead. Always take 150–200ml of water with a conventional gel. If you're using isotonic gels, don't add extra sports drink on top — the combined sugar concentration is too high.

Problem: Bloating or sloshing stomach

Likely cause: Drinking too much fluid at once, or combining high-carb gels with a high-carb sports drink.

Fix: Separate your carb sources from your hydration. Use gels with plain water, or use a carb drink and skip the gels. Don't double up. Aim for 150–250ml per intake, not 400ml in one go.

Problem: Energy crash despite fueling on schedule

Likely cause: You started fueling too late. By the time you feel the crash, you're already 30–45 minutes behind on energy.

Fix: Take your first fuel at 30–40 minutes, before you feel any need for it. Glycogen depletion is a falling tide — you can't see it until you're already stranded.

Problem: Nothing works — everything upsets your stomach

Likely cause: You may be running too hard on your long runs. At high intensity, blood diverts from your gut to your working muscles, shutting down digestion.

Fix: Keep your long runs at an easy, conversational pace. If your gut only tolerates fuel at easy pace, that's fine — race day will be hard, but the adaptation you build at easy pace carries over. Also consider non-gel options: real food (dates, banana pieces, rice balls), chews, or liquid carb drinks that bypass some of the gastric emptying bottleneck.

The Three Things Most Runners Get Wrong

1. Practising nutrition at easy pace but racing at threshold

Your gut behaves differently at 70% effort versus 85% effort. Blood flow to the stomach drops significantly as intensity increases. If you only practise fueling on slow long runs, include at least two sessions where you fuel at race pace — even if it's only for the final 30–45 minutes.

2. Practising with one product but switching on race day

Race expos are dangerous. That free gel sample in a flavour you've never tried? Leave it in your bag. Use the products you've tested. Use the flavours you've tested. Race day is for executing, not experimenting.

3. Ignoring hydration while focusing on fuel

Gels and hydration are a system, not separate strategies. A gel without water sits in your stomach. Too much sports drink with a gel overloads your gut with sugar. Practise the combination, not just the individual parts.

How Much Carbohydrate Do You Actually Need?

The current evidence supports these ranges:

| Race duration | Carbs per hour | Example | |--------------|---------------|---------| | 60–90 minutes | 30–60g | 1–2 gels per hour | | 90 minutes – 3 hours | 60–90g | 2–3 gels per hour or gel + sports drink | | 3+ hours | 80–120g | Multiple sources, practised heavily |

But these are ranges, not prescriptions. Your ideal intake depends on your body weight, your sweat rate, your pace, and — critically — what your gut has been trained to handle.

A 55kg runner targeting a 3:30 marathon has very different needs from a 90kg runner targeting 4:30. Generic ranges don't account for this.

Sweatr calculates your personal carbohydrate ceiling using your wearable data — your training load, heart rate zones, estimated sweat rate, and body metrics. It gives you a specific number, not a range, and maps it to products you can actually buy. That's the difference between a plan and a guess.

Your Pre-Race Confidence Checklist

By race week, you should be able to answer "yes" to every one of these:

• I've tested my exact race-day gels/fuel at least 4 times in training
• I've fueled at race pace at least twice
• I know my carb intake target per hour (not a generic range)
• I've practised my hydration alongside my fueling, not separately
• I've eaten my race-morning breakfast before a long run at least twice
• I know what to do if my stomach turns during the race
• I have a backup plan if my primary gel doesn't work

If you can't tick all of these, you have a plan — but you haven't practised it. And a plan you haven't practised is just a hope.

Build Your Plan, Then Prove It Works

The best race-day nutrition plan is the one you've already tested. Not in theory, not in a spreadsheet — in your legs, on the road, under fatigue.

Start 8 weeks out. Introduce fuel gradually. Build to race-day targets. Simulate everything. Solve problems in training where they're inconvenient, not on race day where they're devastating.

Sweatr builds your personalised fueling and hydration plan from your Apple Watch and Garmin data — specific carb targets, specific fluid volumes, mapped to real products. Then it helps you track what works during your training runs, so by race morning, you're not guessing. You're executing.

Download Sweatr free and build your race-day plan today.