Zinoubi, B, Vandewalle, H, and Driss, T. Modeling of running performances in humans: comparison of power laws and critical speed. J Strength Cond Res 31(7): 1859-1867, 2017-The concepts of power law and critical speed (SCrit) have been applied to the analysis of individual running performances. We have analyzed the results of 2 exceptional runners (Nurmi and Gebrselassie) and 11 physical education students (PESs) who performed 3 exhausting running exercises. Power laws can accurately describe the relationships between exhaustion time (tlim) and distance (Dlim) or speed (S) (Equation is included in full-text article.)in elite runners and PES. However, the validity of the application of power laws must be verified for higher values of tlim in nonelite runners. Exponent γ is close to 1 in elite runners and lower in PESs (from 0.625 to 0.872). The value of SCrit was computed from 2 values of tlim (3-14 minutes; SCrit 3-14) and was expressed as a fraction of maximal aerobic speed (MAS) which was assumed to correspond to the maximal speed that can be sustained over 7 minutes (Equation is included in full-text article.)The individual values of (Equation is included in full-text article.)(0.945 for Gebrselassie, 0.919 for Nurmi, and 0.764 ± 0.078 in PESs) were linearly correlated with γ (r > 0.999) and almost equal to γ (0.952 for Gebrselassie, 0.918 for Nurmi, and 0.779 ± 0.076 for PESs). The same results were observed when SCrit was computed for tlim equal to 6-28 minutes (SCrit 6-28) and MAS was the maximal velocity sustainable during 14 minutes (S14min). The fact that γ is linearly correlated and almost equal to (Equation is included in full-text article.)or (Equation is included in full-text article.)suggests that exponent γ can be considered as an index of aerobic endurance.