Sassi, A, Stefanescu, A, Menaspa, P, Bosio, A, Riggio, M, and Rampinini, E. The cost of running on natural grass and artificial turf surfaces. J Strength Cond Res 25(3): 606-611, 2011-The purpose of this study was to evaluate the metabolic cost of running (Cr) on natural grass (NG) and artificial turf (AT), compared with a hard surface (HS), that is, asphalted track. Eight amateur soccer players (mean ± SD: age 22.9 ± 2.3 years, body mass 69.0 ± 4.7 kg, and height 178 ± 5 cm) completed 9 runs (3 surfaces × 3 speeds, i.e., 2.22, 2.78, 3.33 m·s−1) of 6 minutes, in a random order on the different surfaces. Characteristics of the running surfaces were assessed at 3 points of each running track by measuring shock absorption and standard vertical deformation, via an ‘artificial athlete’ device according to FIFA protocol. No significant interactions (2-way ANOVA analysis; p = 0.38) were found between running surfaces and running speeds. A significant main effect for surface was found. The average Cr values were 4.02 ± 0.25 J·kg·L·m−1 on HS, 4.22 ± 0.35 J·kg·L·m−1 on NG, and 4.21 ± 0.31 J·kg·L·m−1 on AT. The Cr was also higher at 3.33 m·s−1 compared with the Cr measured at the other 2 running speeds. In conclusion, we found a Cr of ∼ 4.20 J·kg·L·m−1 on both natural and artificial grass football pitches, in accordance with similar percentage shock absorption characteristics of these 2 tested surfaces. Our finding allows a better computation of the Cr on NG and AT, and supports the exclusion of the Cr as a potential factor for the higher physical effort in matches played on artificial turf, as reported by soccer players.