Race day guide: 5K, half marathon and marathon
7 min read · Updated 3 Nov 2026The training is done by race week. What’s left is arriving fresh, starting at the right pace and fuelling for the distance. Most of it is the same for every race; the pacing and the fuelling aren’t, so each distance has its own section below.
The week before
Run less, not slower. Keep the shape of a normal week with shorter runs, and keep a little pace in it: a few strides, or a short block at race pace midweek, keeps your legs feeling quick. Sleep is worth more than any session now, especially two nights before the race, because the night before is often a poor one.
Sort out the logistics early. Know how you’re getting to the start, when your pen or wave opens, where the bag drop is, and what you’ll wear for the forecast. Lay it all out the day before, number pinned on.
The night before and race morning
Eat a normal, familiar dinner, a little heavier on carbohydrate, and not late. In the morning, eat the breakfast you’ve had before long runs, two to three hours before the start, and drink a normal amount. Get to the start with time to queue for the toilets twice. Keep an old top on until the last minutes and leave it behind.
| 5K | Half marathon | Marathon | |
|---|---|---|---|
| Warm-up | 15-20 min easy, plus strides | About 10 min easy, a few strides | A few minutes of walking and jogging |
| First kilometre | At goal pace, not faster | A few seconds slower than goal pace | 5-10 s per km slower than goal pace |
| Fuel during | None needed | Water; a gel if you'll be out well over an hour | Carbohydrate from early on, regularly |
| Where it's decided | Kilometres 3 to 4 | The last 5 km | After 30 km |
Racing a 5K
A 5K is short enough that a proper warm-up matters: 15 to 20 minutes of easy running, a few drills if you do them, and four strides, finishing five or ten minutes before the start. Start at goal pace, not faster: the first kilometre always feels easy and it always costs you later. The third and fourth kilometres are where it hurts and where the race is won, so decide in advance to hold pace through them. Save whatever is left for the last 400 metres.
No fuel is needed during a 5K. A normal breakfast or a small snack beforehand is plenty. Our 5K training plan builds to it.
Racing a half marathon
The half rewards patience. Run the first 5 km a few seconds per kilometre slower than goal pace, settle at goal pace through the middle, and decide at 15 km whether you have more. Most runners who miss their time went through 10 km too fast, not too slow.
Take water early and at most stations, in small amounts. If you’ll be running well over an hour, a gel or two helps, taken before you feel you need it, around the middle of the race. Practise this on long runs first: gels are the most common thing that goes wrong on the day. Our half marathon training plan builds to it.
Racing a marathon
A marathon is run on the fuel you start with and the fuel you take in, so the two or three days before matter: eat a little more carbohydrate than usual, at meals you know, while you’re running little. On the day, start 5 to 10 seconds per kilometre slower than goal pace for the first 5 km, then settle. Halfway should feel comfortable; if it doesn’t, ease off now rather than at 35 km.
Start taking carbohydrate early and keep taking it regularly, with water, in the way you practised on your long runs. The hard part comes after 30 km, when running out of carbohydrate and the pace you set early both catch up with you. Runners who paced and fuelled well are the ones still passing people there. Our marathon training plan builds to it.
After the finish
Keep walking for a few minutes, drink, and eat something within the hour. Expect stiff legs for a few days after a half and a week or more after a marathon. Easy running or walking helps; hard sessions can wait until your legs feel normal on the stairs.
Planning the race with Daash
Once Garmin is connected, ask Claude or ChatGPT to put the race on your calendar and build the taper to it. It sets your race pace from your recent runs rather than a calculator, and afterwards it can read the race back to you, kilometre by kilometre.
Questions
How long should I warm up before a race?
The shorter the race, the longer the warm-up. Before a 5K, 15 to 20 minutes of easy running with a few strides. Before a half, 10 minutes of easy jogging and a couple of strides. Before a marathon, a few minutes of walking and gentle jogging is enough: the first kilometres are the warm-up.
Should I try anything new on race day?
No. Not new shoes, a new breakfast, a new gel or a new pace. Everything you use on the day should have been tried on a long run or a hard session first, so race day holds no surprises.
What if it's hot on race day?
Slow down from the start rather than hoping to hold on. A few seconds per kilometre slower than goal pace on a warm day often finishes faster than goal pace that falls apart. Drink to thirst, use the water to cool down, and treat the time goal as a guide, not a rule.