The only sport I was ever deeply involved in was competitive swimming, which is a) an individual and not a team sport, and b) ALWAYS involves the maximum physical effort for the duration of a race. The pre-race adrenaline rush seemed to help a lot of people to go faster, but not me; I was the same speed in competition as in practice. I did experience nervousness before a race, but more on a psychological than a physiological level. I would feel a sense of doom, but my heart rate wouldn't go up much.

Interesting, what you're saying about eustress/distress. I suppose maybe you need a certain level of sympathetic nervous system activation in order to be focused on outside events in real-time. This is what I noticed at a recent lifeguard team competition; I wasn't nervous and I didn't feel pressured to do well, and my performance fell drastically! Maybe next time I won't be so irritated by the pre-competition butterflies, since apparently they serve a purpose.