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Keep sportsperson sweat off the front element?

Couldn't say, but for a complete reversal on my initial post, if the gym is
lit by *fluorescent* light you'll want to use a different film again
otherwise it'll cast green/blue.

It does the same thing it does anywhere.  Puts more money in the pocket of
whoever sold it to you.  :)  Unless you're shooting in a sand storm or in
the ocean surf, a UV filter does nothing but degrade your image.

Actually he is right, the extra piece of glass and the two extra surfaces to
keep clean will degrade the image.

So-called "UV" filters do little more than the glass of the lenses
they are used on, but of course they at least afford innocuous
protection to the front element.  Haze filters are another matter,
they can effectively cut the light off at near UV, or even the more
extreme ones (like the 2A) will eliminate UV altogether (even UVA).

I've always believed that a test is worth 1000 opinions.  Take your
"UV" filter and interpose it between a fluorescent sample and a common
blacklight, then see how much good it does.  Then do the same thing
with a haze filter and let us know.

When shooting fluorescent mineral specimens, a very aggressive UV cut
is needed to prevent the high ambient ultraviolet from creating a
strong bluish cast and fouling up the color.  This is the case also
for digital cameras.  For this application a Kodak 2A haze (also
Vivitar made these) is ideal, and the slight yellowish cast it imparts
can easily be adjusted out in postprocessing if desired.  No other
filter I'm aware of is as effective in eliminating unwanted UV.

Older cameras with simple uncoated lenses were relatively transparent
to near UV, and for these some form of "UV" filter might show a
visible improvement.