I remember once years ago working in an office that was in someone's home and I was ended up ironing in the garden as the weather was lovely. Sneezed all day. We had a doc on call for the business and he popped in and saw me and gave me some medicine. I mentioned that I felt really shattered and he said that sneezing uses nearly every muscle in the body so that could explain it.
I also find now that me breathing can be affected by hay fever and that leaves me really drained too.