Make sure that you are eating correctly the day before your marathon. You should be eating 75% carbs during your meals – but don’t totally pig out. Many runners think that since they are carbo-loading they can just eat and eat and eat. This can cause discomfort during your race. Just eat the amounts of food that you usually eat – but make sure that they are predominately carbs.
Also, don’t try any foods that you have not eaten before. You may be out of town at a race and want to try new things. The day before the race is not the time to do that. Eat foods that you know agree with you. Save the experimenting with local cuisine for the night after your race.
Make sure that you are drinking plenty of water the day before your marathon. I generally keep a water bottle with me and drink from it all during the day. Your urine should be clear or very pale. If it’s not – you need to be drinking more.
It’s alright to do a short and easy run to stay loose. Don’t so anything speedy or strenuous. Many runners like to do a mile or two to simply relax. Or, you can go for a nice easy walk.
Try to rest as much as you can. Many larger races have a race expo where you pick up your race packet. It’s tempting to spend a lot of time there walking around and looking at everything. Just don’t tire yourself out and be sure that you are wearing comfortable shoes.
The night before a marathon, make sure that you have everything that you need ready to go. I always have laid out what I plan on wearing with my racing bib already attached to it. If it’s a race that uses timing chips – make sure that it’s properly attached to your shoes. Also, have any energy gels or anything that you plan on carrying in the race ready to go. Having everything ready the night before will help you to rest better and not be scurrying around the morning of the race.
Also, go through the race packet. Look for any pre-race instructions. There should be information in there that will be useful to you. For instance, parking instructions, shuttle information, water stops, etc. are things that you should be aware of. Also, they may have designated areas where you can plan on meeting up with your family afterwards.
The morning of the race, try to plan on arriving about an hour before the race starts. This will give you plenty of time to stretch out and make those port-a-potty stops. If it’s a larger race, those lines can get pretty long. There are many large races where I make my first “stop” come out of the potty and then get right back in line. That way I know that I won’t be stuck in line when the gun goes off – or not be totally “relieved” when the race starts.