Dates - staple of North African runners !

In-race nutrition doesn't exist in these events.You don't need to eat or ingest anything. Not even water ! Skip the water stations ! In case of very extreme heat, yes, you might swallow a little sip of H2O, but sponging yourself is even more efficacious !

Here in the south of France, the road racing season is till beginning of June, with the most important races in the October to April Period ! It is extremely rare that we have over 30°C temperatures in this case. Surely at the beginning of the Spring in April we can have some hot surprises, but it is most likely mental. Going from 3°C average to 22°C is not that shocking to the body, than switching from 25 to 33°C for instance. There are 3 evening 10k events I know about in July and August. We might run in 30°C or even over, but not under the blazing sun. It is hot, but not drying and cooking you.
Otherwise, the trail running scene never stops. We have events every single weekend, including short and longer ultra trails too.
I just mentioned this, because heat effects nutrition, the outcome of nutrition and race performances too.

Diet

I do not prescribe, nor subscribe any diet. You do what you want, what works for you. You can be vegan, paleo, elemental, micro, Californian or Mediterranean. However, the single most important thing to consider is the nature of the event. 5k and 10k. They are 100% glycolytic. The rate of fat burning is very minimal.

If you start burning fat during at a 5K / 10K event, you are too slow !

If you followed a healthy low fat diet, like an 80/10/10 style vegan approach, you just have to make sure, you hydrate, you focus on salts and sleep.
If your vegan approach is more likely starch based, there are other things to consider too, what we will cover in the next paragraph.

For high fat athletes, you must understand, that eating a general high fat diet, reduces your ability to store glycogen. The top levels might be chopped off. Your endurance might be fantastic, your health might be stunning, but it might be possible, that you don't have enough mobilisable glycogen to cover the distance at extreme speeds. This is why for instance Zack Bitter, while staying in the very high fat, very low carb zone as the full year goes, uses carbs and a lot of carbs, strategically during high energy output training and events !
On the contrary, athletes reporting on low carb diets talk about loosing the high end and feeling the lack of the final gear. That will be negative when the final K and the finishing kick comes into the picture. Either ways, to safely and surely top up your stores, avoid any high intensity efforts in the last 72 to 96hours before race, in case you stick to your no-carb diet.
If you decided near full on performance, consider a carb backloading approach on a couple of days during each week leading up to your event for 45 days. No, don't go pasta and cookies. Just use more steamed carrots, yams, manioca and cooking bananas. Maybe have couple of fruits.

https://www.ncbi.nlm.nih.gov/pubmed/2308519
https://www.ncbi.nlm.nih.gov/pubmed/2731529
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4672014/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6019055/

The basic recommendations are also all present especially in these upcoming 3 days. No fats and carbs together. Avoid drinking water 20minutes before and after the meals. No alcohol. No snacking. No pre-processed, packaged foods. If you decided to make a home made pizza or cookies, I have no issues with this. Sour-dough, vegetables, olives with 4-5 slices of organic pepperoni, is not a canola oil pumped, bleached flour made, preservatives and additives filled cheap frozen pizza !
Stop heavy combinations, but go simple. 3-4-5 ingredients top ! This will enhance digestion and elimination !
I suppose you don't drink more than two real coffees a day. No capsules and crap like that. No sugary hot chocolate, no Coke, no Fanta, no juices and so. Normal !

Race day count down

Day - 3

This is the day, when you start avoiding fibre, uncooked vegetables, hardy meats, fermented products, nuts and seeds and their butters. Also eliminating little seed fruits like kiwi, figgs, strawberries and berries in general. You don't have to be extremely afraid, just cautious. Eating half a kiwi and 10blueberries is no big deal, but a full barquette of strawberries might cause issues. You can start peeling your veggies and fruits. I don't do it ever, only on these three days. I even cook and eat my butternut squash and sweet potatoes with skin ! Not in this case though !

The human body takes 24 to 36h to be rehydrated and salt levels reestablished, if anything was slightly disturbed. 3 days out you still have time to focus on drinking more water. I am a very active person. Plain water doesn't cut it for me ! I add a pinch of salt and a pinch of magnesium flakes to each litre water consumed. Also I drink and I recommend you to drink 1L of high mineral content quality all-natural sparkling water each of the days till race. This includes race morning ! 3,5 litres for men and 2,5 for women, at least ! Avoid plain water. It can wash you out and cause mineral depletion. We talk about healthy people here with no processed food intake and no processed salt intake. If you were a junk food eater, adding high-mineral water to your lifestyle might cause health issues in case of blood-pressure and heart function !

No milk products, no cheese, no yoghurt, no nothing. Avoid eating meat or any processed meats 3 times a day.
Avoid the egg !
Avoid garlic, onion, chives, leeks and other high sulphur and picky veggies. Including chilly !

Example:
Breakfast: Steamed plantain, with coconut flakes and cinnamon
Lunch: Salad of : butter-lettuce, olives, cherry tomatoes, avocado, can of sardines, some olive oil
Dinner: Basmati rice served with spinach leaves

Day - 2

Start avoiding, potatoes, tomatoes, cucumbers, aubergines, peppers. Avoid steamed sulphur rich veggies too like broccoli, brussel sprouts, cauliflowers, cabbage. Avoid any spices except salt and lemon juice.

No more beans, peas and lentils, nor hummus or garbanzo.

This evening I recommend a medium sized fresh, organic steak. I eat meat maybe once every 15 days. Athletes reportedly talk about a steak dinner 2-3-4 days out of an A race, as performance enhancer ! I encourage this as it works very well !

Example:
Breakfast: 2 big sweet potatoes peeled and steamed with salt and honey
Lunch: Baby chards and baby rocket, an avocado, an apple sliced in and a mango.
Dinner: Organic, grassfed, quality medium size steak marinated at least 24h in advance, served with soft lettuce leaves

Day - 1

A very simple but still calorically rich and digestively simple day. Keep all the eliminations and stick to the plan. Have your last meal at least 12 hours before race and at least 2hours before sleep ! Keep a big gap between meals. Keep your blood sugar stable. Drink only water.

Example:
Breakfast: Porridge made with water and salt. You can use almond milk if wanted. Served with fresh or dried apricots and a banana. They are rich in potassium. Sprinkle cinnamon and add honey if needed !
Lunch: A Yellow Melon. 3-4 mangoes. Maybe 3-4 ripe peaches.
If you were sensitive to quantity of fruits, go with starches. Rice, potatoes, pumpkin and squash. Oven made squash is great. You can slice it up and eat it with some coconut cream and unsweetened cacao powder.
Dinner: Polenta: Sweat or salty. I might eat it with olives or a piece of fruit. Maybe normal boiled potatoes. If organic, you can even drink the water left after boiling.

The thing is that you have to clean out your digestive track the most possible. The 4 factors of no snacking at all, eating clean and simple, having big gaps between meals and high (correct) water consumption will do that. No other special precautions needed. 2 or 3 meals a day, no snacks, 6-8hours between meals. 8am / 14pm / 8pm. 21:30 bedtime. 22:00 sleep.

Race Day:

I don't like to complicate this either. 4,5 hours before the race, I wake up and drink 5dl of water with salt and maybe small teaspoon of apple cider vinegar. In 30min: Coffee and a date. I use coffee for really get the digestion going. I also eat one big medjool date. Two if I felt hungry.

Some of you are more into a tea and a small slice of sweet potato.
There might be runners who prefer to have a slightly bigger lunch the day before, eat little dinner, wake up later and have nothing but sparkling water before the event.
I tested out drinking a strong green tea with two teaspoons of manuka honey, 2g of l-carnitine and 5g of crea-pure creatine. I had the same good results with coffee and a date.
Leave the real meals out of the picture. Eating porridge, a smoothie, a sandwich or anything big will just bring you stiff trunk, hindered digestion, stiff muscles.
Avoid citrus fruits and specially citrus fruits and caffein together ! Cramp combo ! No lemon in your morning infusion
Definitely no yoghurt, no kefir, no soy
Meal replacement powders might work for you to top up glycogen stores and keep the stomach in tact. 50 to 80g of Ambronite or Organifi !
For the extremely sensitive maybe a medical meal replacement like Insure would work, but I'd recommend to get your stomach back to action way before the race !

One final thing to consider. Digestive problems. Very often with fasting, intermittent fasting and with the use of pre and probiotics, digestive enzymes we can heal or enhance digestion. I prefer to leave this out well before the race and by the guidance of a professional. For instance a 4 week cure, till the last Sunday before race day.

These are recommendations. Some of them are very crucial like meal gaps, simplicity, good hydration, good sleep. Others like fibre avoidance and possible allergenic food elimination are advices ! I also did not talk about personal hygiene like washing hands, cleaning mouth, nose ears, sleeping in fresh aired out bedroom, getting sunlight, and so. Supplements and other products can come into the picture too.

This article though can still give you some ideas about what might went wrong in your last race !

Running / pre-race meal

5K / 10K race nutrition & hydration

5K / 10K race nutrition & hydration

5K / 10K race nutrition & hydration