Did this term for a muscular leg cramp arise from a lame horse named Charley that pulled a roller across the infield in the Chicago White Sox ball park in the 1890s? There probably was such a horse, but the expression had been printed several years before his working days, in 1888, to describe a ballplayer’s stiffness or lameness. Another ingenious derivation traces Charley horse to the constables or Charleys of seventeenth-century England. This term for local police survived in the United States through the nineteenth century and because aching legs, as well as flat feet, were an occupational disease among Charleys, ballplayers suffering such maladies were compared with the coppers and said to be “weary for riding Charley’s horse.” Both theories, however, are speculations and the term’s origin remains unknown.