Last year in English I had to deliver a speech, and I was pretty good at acting out the body language and inflecting my voice (I kept picturing that I was one of those politicians), while having trouble in an oral French exam because I never looked at my partner. (Thankfully, the teacher was understanding and did not count such things against me.)
Still, I do far better if I am speaking to a large group of people (it is much easier for me to use eye contact in such situations as well as to not get stage fright). Of course, it probably helped that my speech was memorized, which the teacher discouraged doing because she thought it would cause more monotone lack of inflections, but since I'd memorized my inflections ahead of time, that didn't pose a problem.
Debate is a tougher thing, of course, but I know what it's like to end up doing all the work without getting any credit (my first five-and-a-half years of school group work). It's never easy and always frustrating.
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"There are things you need not know of, though you live and die in vain,
There are souls more sick of pleasure than you are sick of pain"
--G. K. Chesterton, The Aristocrat