I just finished running a Spartan Beast race this past weekend and wanted to pass on some of the things I learned in case anyone else was interested in participating. First, don't train for the obstacles, train for cardiovascular fitness, so that means run, run, run. I always thought my cardio was pretty good until I ran this race; the course included 4 trips up and down a 400-500m (1280 ft) mountain. It also didn't help that the race was extended by 5km to 25km.
Second, wear a hydration pack, like a Camelbak. There were water stations but they were few and far between and you go dry pretty fast running mountain trails in 30C temperatures. I saw more than a few racers on the side of the trail hit with muscle cramps due to dehydration.
Third, bring energy gel and salt tablets to take during the race. Talking to the experienced racers there, every single one of them brought energy bars or energy gel with them on the trail. I didn't think it was necessary until I hit the 2/3 mark and was faced with the last ascent and realized that the tank was empty. Salt tablets also would have helped with the cramping I was feeling at that point.
Finally, don't start with a Spartan Beast race if you've never run an obstacle race before, go for a Spartan sprint or the 10km race.
This was the hardest thing I've ever done and made me realize I'm not in as good a shape as I thought I was. I was miserable and hurting during the last 5km and my finish time was pretty sad. Having said that, I'm doing this again next year! I met some great people out there and I really want to get my finish time down.