While competing in an obstacle course race, a 57-year-old male athlete developed left groin and leg pain. Several days later, infrarenal aortic dissection with clinically worsening left leg ischemia was diagnosed. An emergent repair was performed and consisted of an aorto-uni-iliac endovascular stent graft, an occluder in the left iliac artery, and a right-to-left femoral-femoral artery bypass. To the authors’ knowledge, the present report is the first case of a spontaneous infrarenal aortic dissection in a competitive athlete associated with participation in an extreme athletic event.