Malignant hyperthermia (MH) episodes may occur upon exposure to halogenated anesthetics, during resistance and endurance exercise, and in response to thermal stress. The purpose of this study was to investigate the effects of prior eccentric and concentric (i.e., wheel running) exercise on the thermal sensitivity of isolated MH-susceptible mouse muscle (RyR1(Y522S/wt)). Eccentric, but not concentric, exercise attenuated the thermal sensitivity of MH-susceptible muscle.