The purpose of this study was to prospectively investigate the specificity effect of two different treadmill protocols on maximal oxygen consumption (VO2max) in highly-trained distance runners (n=16). The secondary purpose examined if the ventilatory threshold (VT) attained during different protocols occurred at the same percent of VO2max (% VO2max @ VT). After a familiarization session performing the Bruce Protocol, VO2max was evaluated using two graded treadmill protocols; a horizontal (increment in speed only) (SOVO2max) and inclined (constant speed with increment in grade only) (GOVO2max). VO2max values were significantly higher from the GOVO2max in comparison to the SOVO2max protocol (76.1 and 71.2 mLO2/kg/min, p=. 005). The % VO2max @ VT was not significantly different between the GOVO2max and SOVO2max protocols. The results indicate that, based on runner specialty (flat versus hill runners), either SOVO2max or GOVO2max protocols can be used to determine the % VO2max @ VT in highly-trained distance runners.