SummaryThe gross energy cost of treadmill and track running is re-investigated from data published in the literature. An average equation, weighted for the number of subjects in each study, was found: V̇O2(ml/kg/min) = 2.209 + 3.163 speed (km/h) for 130 subjects (trained and untrained males and females) and 10 treadmill studies. On the track, wind resistance as predicted by Pugh (1970) was added to the treadmill cost of running and yielded the following equation for adults of average weight and height: V̇O2= 2.209 + 3.163 speed + 0.000525542 speed3. Between 8 and 25 km/h, the following linear equation: V̇O2= 3.5 speed (or met = km/h) was very close to the cubic equation. This linear equation for track running is, however, different from the treadmill linear equation, particularly for speeds over 15 km/h. This equation is also slightly different from the one published by Pugh (1970) for track running from 7 trained subjects only.