from: http://www.newadvent.org/cathen/11635c.htm

The Hermanos Penitentes are a society of individuals, who, to atone for their sins, practise penances which consist principally of flagellation, carrying heavy crosses, binding the body to a cross, and tying the limbs to hinder the circulation of the blood. These practices have prevailed in Colorado and New Mexico since the beginning of the nineteenth century. Up to the year 1890, they were public; at present they are secret, though not strictly.