Left to right: Marco Caremani, Massimo Reconditi, Vincenzo Lombardi, Elisabetta Brunello, and colleagues discovered that cold temperatures convert myosin motors in mouse skeletal muscle at rest to a disordered refractory state unable to bind actin upon muscle activation. This refractory population is revealed by x-ray diffraction measurements showing that, in resting muscle, low temperatures reduce the number of myosin motors in the ordered OFF state (top graph) whereas, in contracting muscle, low temperatures cause a parallel reduction in the number of actin-attached motors (bottom graph).