How to prepare for marathon race day: a race-week guide
- Helen Morton
- 3 hours ago
- 10 min read
What to eat and do in the week before, on race morning, and in every mile to the finish line. By Helen Morton, nutritional therapist and runner.
You’ve done the training, your kit is ready, and race day is finally within sight. Marathon race day preparation is everything from the final week, through race morning, to the moment you cross the finish line, and it makes a real difference to how your marathon unfolds. This guide covers what you need in order to arrive at the start line feeling prepared, calm, and ready to run your best race.
In this article, we'll explore:
The week before your marathon
What should you eat in the week before a marathon?
The golden rule of race week nutrition is simple: don’t experiment. Stick to the foods you know, meals you’ve eaten throughout training, and ingredients your gut is familiar with. A new restaurant the evening before your marathon or an unfamiliar pre-run snack on race day might seem harmless, but your digestive system is more sensitive than usual in race week, and an upset stomach is one of the most avoidable race-day disasters.
Beyond keeping food familiar, the main nutritional focus of race week is carbohydrates. You want to arrive at the start line with your glycogen stores—your body’s primary fuel source for the race—as full as possible. This doesn’t mean forcing down bowls of pasta at every meal. It simply means making carbohydrates the focus of your plate across the week: bread, oats, rice, pasta, potatoes, fruit. Keep meals moderate in size, easy to digest, and low in anything that might cause bloating or gastrointestinal discomfort, which means less fibre, less fat, and less spice than usual in the final two to three days.
Stay hydrated consistently throughout the week, but don’t overdo it. Drinking excessive amounts of water in the days before a marathon won’t top up your hydration any more effectively than drinking steadily and sensibly. In fact, drinking too much water can leave you feeling quite uncomfortable.
What does carb-loading actually mean, and how do you do it?
Carb loading has been around since the 1960s and has since gone through several reinventions. The original protocols were fairly extreme, primarily involving a depletion phase followed by a loading phase. This is rarely recommended now and current thinking is considerably more straightforward.
When you run, your body breaks down carbohydrates into glucose, which is either used immediately for energy or stored as glycogen in your muscles and liver. Your glycogen stores have a finite capacity, and once they run low, typically around the 18 to 20 mile mark in a marathon, your body has to work much harder to keep going. This is what hitting the wall feels like.
Carb loading simply means strategically increasing your carbohydrate intake in the days before the race to ensure those stores are as full as possible before you start. For most recreational runners, this means shifting the balance of your plate towards carbohydrates for the final two to three days. There is no need to dramatically increase your total calorie intake, just make carbs the priority at each meal. Think a generous bowl of porridge for breakfast, a jacket potato at lunch, pasta or rice with dinner, and fruit as snacks. The aim is to be consistent, not to eat until you’re uncomfortable.
Want to learn more about carbohydrates? Nutritional therapist and founder of The Health Puzzle Josie Shillabeer shares all in the self-guided online course 'Carbohydrates: are they fuelling your body or holding you back?', click here to find out more.
Should you cut caffeine and alcohol before a marathon?
Caffeine
If you’re a regular coffee drinker, cutting caffeine out entirely during race week is likely to cause more problems than it solves. Caffeine withdrawal headaches typically kick in within 24 to 48 hours of stopping and can last several days, which would not be ideal timing when you want to feel your best during your marathon. A better approach is to keep your usual intake steady during the week, perhaps reducing slightly in the final day or two if you feel you’re in any way sensitive to caffeine.
It’s worth knowing that caffeine is a well-researched ergogenic aid, meaning it has a genuine, evidence-based performance benefit for many runners. If you already use caffeine during training runs, race day is not the time to change that. And if you’ve never used caffeine for performance benefits, don’t start now.
Alcohol
The research behind avoiding alcohol in race week is more straightforward. Alcohol is dehydrating, depletes B vitamins, disrupts sleep quality even in moderate amounts, and impairs recovery and muscle glycogen storage. Ideally, cut out alcohol for the final week.
How important is sleep during marathon race week?
Sleep is more important than you might expect, though perhaps not in the way you think.
The night before a marathon is notoriously difficult to sleep well through. A combination of nerves, excitement, an unfamiliar bed if you’re staying away, and an early alarm means that most runners don’t sleep brilliantly on the eve of their marathon. However, be reassured that one poor night’s sleep has very little impact on physical performance. Your body has weeks of good training and recovery behind it and just one restless night won’t undo that. What matters far more is the sleep you get in the three to four nights before race day. This is where your real recovery and preparation happens, and it really is worth prioritising. Go to bed a little earlier than usual, protect your wind-down routine, and resist the temptation to stay up late scrolling through race-day tips or checking the weather forecast for the umpteenth time. Bank as much rest, both physically and mentally, as you can in the days leading up to the big day, and try not to lose sleep over the fact that you’re not sleeping.
Read Chandy's guide on how to get a good night's sleep for more in-depth sleep guidance.
How much should you taper in race week?
Tapering is the process of reducing your training load in the weeks before a marathon to allow your body to recover and arrive at the start line fresh. If you’ve followed a structured training plan, you’ll likely have been tapering for two to three weeks already, with race week representing the lightest training volume of your entire block.
In race week itself, keep any running you do very short and easy. I like to do a couple of gentle twenty minute runs at most, purely to keep my legs ticking over and my mind settled. This is not the week to try to cram in extra miles, do a final long run, or test your race pace. Ultimately you need to trust the training you’ve done and resist the urge to do more.
Many runners experience a kind of “taper madness”, typically a combination of restlessness, phantom niggles, and sudden conviction that they haven’t done enough training. This is entirely normal. Keep busy, rest well, and let your body do what it needs to do.
How do you manage pre-race nerves?
Having some nerves is useful because they sharpen focus and prime your body for effort. But the anxiety that can build in race week, particularly before a first marathon, can be genuinely uncomfortable and it really is worth having a strategy for.
First, recognise that nerves are a sign that this matters to you, which is a good thing. Then take practical action: lay your kit out early, pin your race number on if you already have it, pack your supplies of food, plan your travel and parking, and know where the bag drop is. The more decisions you make in advance, the less mental load you’re carrying on race morning.
If your mind is running away with worst-case scenarios, it can help to come back to what you know. You have done the training, you know how to fuel and hydrate, you have run long distances before. A first marathon is unknown territory, but you are ready for it.
Marathon race day
What should you eat for breakfast before a marathon?
Aim to eat breakfast two to three hours before your start time, as you usually would before a long training run. In practice this may mean setting an earlier alarm than feels reasonable, but it’s worth it. You need food in your system and fully digested before you’re standing on the start line.
Stick to what you’ve eaten before your long training runs. This is not the morning for something new, however tempting the hotel breakfast buffet might be. A bowl of porridge with banana, toast with peanut butter, or a bagel with honey are all reliable options because they are slow-release carbohydrates that will fuel your early miles without sitting heavily in your stomach.
Drink a large glass or two of water when you wake up. If you normally have coffee before a long run and your stomach tolerates it well, race morning is fine to do that too. However, it’s worth knowing that nerves can affect how your gut responds to caffeine, so if you’re in any doubt, leave the coffee.
How do you fuel during a marathon?
Stick to exactly what you’ve practised in training. As already explained, race day is not the time to try a new gel brand, a different flavour, or a fuelling strategy you heard about the night before. Your gut has been trained alongside your legs and you need to honour that.
As a general guide, aim to take on carbohydrates every 30 to 45 minutes from around the 45-minute to one-hour mark, before you feel like you actually need anything. Waiting until you feel depleted is too late because by the time energy levels drop noticeably, you’re already behind. Whether you’re using gels, chews, dates, or flapjack, take them with water rather than dry, and remember to sip water not gulp to avoid excess air going into your stomach.
On a practical note, keep your pacing in check in the early miles of a marathon. The excitement and crowd energy at the start of a big race make it very easy to go out too fast, but you’ll pay for it later. Run your own race right from the beginning.
Do you need electrolytes before or during a marathon?
Yes, and this becomes increasingly important the warmer the day. When you sweat, you lose not just fluid but sodium, potassium, and magnesium, and replacing fluid alone without replacing electrolytes can actually worsen the imbalance.
Sip water little and often at the water stations rather than drinking large volumes infrequently. If you’re a heavy sweater, run hot, or it’s a warm race day, consider using electrolyte tablets or sachets in your water, or carrying electrolyte chews alongside your gels. Hopefully you will have already tried these out during your training runs. The difference that taking electrolytes can make to how you feel in the second half of the marathon is significant.
Read our guide to the best electrolyte drinks and supplements for sports and health
What happens if you hit the wall?
First off: don’t panic. Hitting the wall, which feels like a sudden, overwhelming sense of exhaustion that typically strikes somewhere between miles 18 and 22, happens when your glycogen stores run low and subsequently your body struggles to maintain pace. It happens to plenty of experienced runners, not just first-timers, but importantly it does not mean your race is over.
If it happens, slow down rather than stop. Walk through a water station or up a big hill if you need to. It is vital to take a gel or some fast-release carbohydrate and give it ten to fifteen minutes to work. All the while talk to yourself kindly. What you’re experiencing is physiological and it will shift. Many runners have their best final miles after hitting the wall and working through it.
The best defence against hitting the wall in the first place is the fuelling strategy you’ve practised: consistent, proactive, starting early enough that you never reach empty. But if the wall hits anyway, know that you have more in you than it feels like you do in that moment. Positive self talk matters.
Should you eat as soon as you cross the finish line?
First things first: celebrate! You have done something genuinely amazing, and that deserves a moment of celebration.
Then, yes, what you do in the hour after finishing matters for your recovery. Your body is primed to replenish glycogen stores and begin muscle repair, and giving it the right fuel in this window makes a real difference to how you feel in the days that follow. Ideally you want to be eating carbohydrates and protein together, like a recovery drink, a banana and a protein bar, or whatever your finish line food bag contains. Start rehydrating with small sips of water before anything else. Alcohol after a marathon is very common and understandable, but your body will thank you for getting some fluid and foods in first.
Top tips (things I did wrong so you don’t have to)
Plan to arrive in plenty of time: large marathons involve significant logistics. Bag drop queues, toilet queues, and walking to your start pen all take longer than you expect. Build in more time than you think you need, then add some more.
Queue early for the portaloos, then queue again: the queues before a big race are long and they don’t get shorter the closer to the start time you get. Go early, go again, and make peace with the fact that this is simply part of the marathon experience.
Don’t drink huge quantities of water straight after finishing: sip steadily rather than gulping large amounts immediately after crossing the line. Your body needs time to rebalance.
Have someone waiting with warm, dry clothes: you will quickly feel colder than you expect once you stop moving. A warm layer, dry socks, and maybe a foil blanket make the post-finish experience considerably more comfortable.
Final thoughts
Race week and race day are the culmination of months of your work, and the details in this guide are the final piece that brings it all together. Trust your training, stick to what you know, fuel proactively, and enjoy every mile of the marathon.
In the final article in this series, we’ll cover what happens after the finish line, including what DOMS actually is, how to support your recovery, and why feeling a little flat in the days after your marathon is more normal than you might think.
If you are earlier in your training block, start with how to prepare for your first marathon, our beginner’s guide to the months before race day.
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