1816, Race-horses, method of preparing for running, entry in Encyclopædia Perthensis, 2nd Edition, Volume 18, page 571, If the horse be in good fleſh and ſpirits when taken up for its month′s preparation, the diapente muſt be omitted; and the chief buſineſs will be to give him good food, and ſo much exerciſe as will keep him in wind, without overſweating him or exhauſting his ſpirits.
Source: wiktionary