Shower immediately after exercising - easy.
Exercising creates sweat all over your body. Sweat smells. You cant deodorize your whole body, only solution is to wash it off.
As others have said, it's not the sweat that smells it's the bacteria that thrive on it. But they generally only thrive in protected crevasses like armpits, and not on exposed skin where they regularly get rubbed off. Deodourising is literally trying to hide a bad smell with a better one. Again, as others have said, anti-persoirant will actually stop the sweat in the first place, and...
Very bad idea to cover your sweat glands with aluminium oxide before a workout.
No, it's not. You're not blocking every pore. Just those pores in your armpits where bacteria are more likely to do well.
The other thing to consider is that man-made fibres are excellent for sweat-wicking but do seem to get foul-smelling quickly. Merino wool is much less smelly. There are also some treatments for sports fabrics and travel clothing which they claim makes clothes less smelly.
If you can't shower immediately after exercise, a pack of wet wipes to get the worst off the pits can work quite well.
Hope that helps.