Without getting into whether pants is right or wrong on a woman - that is something you would have to study out for yourself - let's deal with this hypothetically:

If Deuteronomy 22:5 is referring to pants (or including pants), then perhaps God does not want women doing those activities that they would be forced to wear clothing He is against them wearing. There is one woman I have spoken with on another board that decided for pants because she wanted to skydive and could not imagine doing so in a dress or skirt. However, because God doesn't want women (and of course men too) wearing immodest clothing in general, then it logically fits that He would not want them participating in certain activities that would involve them wearing wrong or immodest clothing. Perhaps they shouldn't be doing that particular activity, perhaps they can still wear modest clothing in that setting - but would need to adapt what they wear or how they wear it and/or how specifically they are involved in the activity.

My point, we don't decide doctrine and standards based on what we want to do - we should be doing what is consistent with what we believe the Bible is teaching we should act, live, wear, etc.

An example: I don't go work out at public gyms or swim in public. Sure, I like to work out - but the music at a public gym is dangerous for me spiritually, the way people are dressed (at the gyms, beaches and public pools) is entirely immodest - even if I personally wore a shirt and shorts that covered my thighs (to uncover these areas is called nakedness in the Bible), others will not be dressed modestly. I would be putting myself in a position that causes me to compromise, and be seeing others improperly dressed (even if I am not lusting, I would still be continuously putting images in my mind by choosing to be there). It is not wrong to work out, get in shape, or swim, but in those environments, I believe it would be.