DEN

Here's what I found ( as others have mentioned):
The G-Force Health Club. In the Dubai International Hotel, to the right and behind the Reception Desk.

I was in the transit ( or connections) area so I had to go through security screening but no passport control. Simple and quick and the hotel is in the same terminal.

Shower only: 44 AED or $13
Gym access and Shower 64 AED or $20

I did the gym and the shower since I had until 9:30P before I could check in.

I probably would have eaten or spent the $20 if I stayed in the terminal so it was probably a wash for me and definately I feel better for the return flight ( and smell better).

I was told there is a pay-for-use Business Lounge run by the airport authority with showers but I wasn't able to find it.

Thanks for your help.

DEN