Press Day at the Venice Biennale. A hundred yards apart, two people pound away on step machines. One, male, is perched on an upside-down tank, its tracks spinning helplessly as if propelled by his running. This, you will have guessed, is art – American art, in fact, the jogger-and-tank being in a show in the US Pavilion by the collaborative duo, Jennifer Allora and Guillermo Calzadilla.
