I've heard mixed messages, how long do you need to warm up for the swim before a sprint tri (500-750m - pool swim)? The last two sprints I did I had leg cramps during both of them. I think I have decent speed, but near the end my calves start to lock up, and I'm wondering if this is from not warming up enough. My concern is that I'll wear myself out on the warmup and not have as much left for the actual event. I've heard of doing warmups for a sprint for as long as an hour and as little as 20 minutes. What does experince say?