I do get butterflies right before the start but I would consider this normal. During my training rides at race pace I do not go full throttle right out of the gate and I believe this is the difference. Personally I hate going flat out right from the gun but in MTB XC racing you really have no other choice(the 1st 1/4 mile or so is typically an all out sprint to get ahead of as many riders as possible before the course narrows to singeltrack). As a result I tend to really suffer the first 20 mins. or so but eventually settle in and try to get on the wheel of a rider I know who will be in the top 10 in my class. I'm guessing I'm building up a lot of lactic acid right at the very start of the race which is atypical vs. my hard training rides. I also try to get a good warm up in but inevitably I end up standing around for 40 mins or so at the start waiting for my class / age group to begin so any warm up I've gotten in is diminished.
Originally Posted by
himespau
Is there any chance it's a mental thing? I'm not trying to imply that you're not cut out to race or are crazy or anything, but, if you have trained at race pace for longer periods in the past with no cramping, the one thing that seems to be missing is the race itself. Maybe you're tensing up a bit more without realizing it and having to work harder against yourself and that's causing some of the problems?