Sidewalk musicians play the blues on the Charles Bridge while the blazing embers of the summer sun begin to fade behind Prague Castle.  Rounded cobblestones meet the perpendicular angles of the platform mules I balance in with sharp abrasive taps.  I tighten my core as I weave through ambling crowds of tourists gawking at the saints perched on the thousand year old passageway, training for competition with the beautiful Slovakian princesses and Italian models that now glide past me, smoothly…