Alcohol is a tricky substance when it comes to runners. You don’t have to give up alcohol entirely, but too much will leave you dehydrated. If you drink the night before a run, you can be sure to expect a slower time and a decrease in performance. If you are going to drink alcohol, beer is actually a better choice for you than hard alcohol because it contains more water. Also, avoid mixed drinks since most contain juices that have preservatives in them, not to mention other additives that will slow you down the next day.