If you have cramps the day after, maybe you should get in better shape.
After racing bicycles, skis and now dirtbikes for many many years, i find i only get tired and sore if i'm in crappy shape or if i drink a bunch after a race. My simple strategy:
1. hydrate during and immediately after the event. Make sure to get some complex carbs into your body as soon as possible after you finish.
2. don't overeat. eating too much slows recovery and makes you lethargic.
3. don't overdrink. a beer or two is not a big deal, but if you have 10, expect your recovery to take a few extra days.
4. consider stretching at doing light exercise just to warm up your muscles and promote circulation the day after an event.
The only time i really worry about that stuff anymore is at a 2-day event like idaho city where i'm on the bike riding hard for 6 hours each day. I limit my alcohol intake severely, eat small amounts often, stretch, rest, and always seem to ride faster and place higher on the 2nd day.