When prolonging the time of recovery up to 30 minutes, all blood gas parameters except HbO2 were similar to pre- exercise values, indicating that the duration of the recov- ery phase was sufficient to ensure the return of the parameters under evaluation within physiological ranges. This assumption was however not applicable when considering the horse body temperature and levels of circulating nitrite þ nitrate. In fact, ANOVA showed a sig- nificant effect of SET on body temperature (F2,14 1⁄4 155, P < .001) and circulating NOx (F2,14 1⁄4 6.11, P < .05).