In my months of training for my marathon, I have learned one indefatigable truth: drinking a lot of alcohol on the night before a long run is quite detrimental for your performance.
Sure, there are the typical circumstances that generally accompany consumption of a few drinks, such as possibly being out late and having less sleep. Then, there are the other adverse physical effects. Alcohol, of course, is a diuretic, which leads to dehydration. It causes the body to lose fluids quicker, impairs performance and makes those long runs even tougher. By extension, drinking alcohol also significantly increases the rate of urination. There have been times I’ve gone out on long runs (after a night of drinking) and had to stop to use the restroom multiple times.
Not surprisingly, most articles providing advice on running marathons generally discourage drinking on the night before the race. At the same time, many runners are used to drinking beer or wine on almost a nightly basis. It can certainly be done. Witness former U.S. Olympic marathoner Deena Kastor, who used to drink a glass of wine before races, including before her bronze medal performance. Hey, if it’s good enough for an Olympic bronze medal, it’s good enough for me. If nothing else, it would help calm the nerves, and, after all, you shouldn’t stop what you have been doing all throughout training right before the marathon.
With that said, it appears to be ok, for those who are used to drinking wine or beer, to have ONE (and only one) glass of wine on the night before the race, particularly having it early in the evening with dinner. Accompanying the drink with adequate water afterwards is also for the best. Of course, if my performance during the race is below par or if I end up having to stop for restroom breaks multiple times, I also then have a built-in excuse.