Madonna's Sweaty Hot Flash

5/8/2008 3:57 PM PDT BY TMZ STAFF
Madonna is turning 50 in August and will soon undergo the change ... of clothes.

The drenched in sweat musclebound material marm -- who currently has the #1 album in the country -- was snapped leaving a private gym in London on Wednesday.

Madge doesn't work out her vadge in just any ol' Ballys!